Inorganic Chemistry
Transcription
Inorganic Chemistry
Content INC: Inorganic Chemistry Paper Tittle ID 24 PREPARATION OF CRYSTALLINE NANOSEEDS OF BEA STRUCTURETO INDUCE FORMATION OF ZEOLITE BETA 45 A COLORIMETRIC SENSOR BASED ON 3,5DIHYDROXYTOLUENE AND 4-NITROPHENYL FOR ANION 81 102 128 147 151 SYNTHESIS AND CHARACTERIZATION OF COPPER(II) AND NICKEL(II) COMPLEXES OF HEXAAZA MACROCYCLIC LIGANDS Cu(II) AND Zn(II) COMPLEXES OF POLYDENTATE SCHIFF BASE LIGANDS: SYNTHESIS, CHARACTERIZATION, PROPERTIES AND BIOLOGICAL ACTIVITY SOME FIRST ROW TRANSITION COMPLEXES WITH ACETYLACETONATE AND TETRAAZAMACROCYCLIC LIGANDS FOR ANTIBACTERIAL ACTIVITY Authors Pages Siriluck Tesana, Aticha Chaisuwan 166-169 Paengkwan Jansukra, Apisit Songsasen, Thawatchai Tuntulan, Boontana Wannalerse 170-173 Surachai Kongchoo, Anob Kantacha, Sumpun Wongnawa Abdulaziz M. Ajlouni, Ahmed. K. Hijazi, Ziyad A. Taha , Waleed Al Momani Tossapon Phromsatit, Supakorn Boonyuen, Natthakorn Phadugsak , Pornsan Luangsriprech 174-177 ONE POT SYNTHESIS OF FREE BASE MESOJantima Sukjan, TETRA (SUBSTITUTED PHENYL) PORPHYRINS Supakorn Boonyuen, Wootthiphan Jantayot SYNTHESIS AND CHARACTERIZATION OF Wootthiphan Jantayot, LONG CHAINED PORPHYRIN DERIVATIVES Supakorn Boonyuen, AND COBALT COMPLEXES Jantima Sukjan, Kamolnate Jansaeng 178-181 182-186 187-189 190-193 204 214 261 281 289 316 366 380 397 SYNTHESES OF MAGNETIC NANOCOMPOSITE SIZE SERIES PREPARATION OF PERCHLORTE ANION SELECTIVE MEMBRANE ELECTRODES FROM DONNAN EXCLUSION FAILURE PHENOMENON INDUCED BY METAL IONS BIMETALLIC ALUMINUM COMPLEXES SUPPORTED BY METHYLENE BRIDGED BIS(PHENOXY-IMINE) LIGANDS FOR THE ROP OF RAC-LACTIDE GOLD NANOPARTICLES WITH POLYANILINE FOR SELECTIVE COUPLING AND OXIDATION REACTIONS OF ARYL BORONIC AND ITS SUBSTITUTES CRYSTAL STRUCTURE OF SILVER(I) CHLORIDE COMPLEX WITH N-ALLYLTHIOUREA AND TRIPHENYLPHOSPHINE SYNTHESIS AND CHARACTERIZATION OF CADMIUM(II) COMPLEX WITH 4,4'-BIPYRIDINE AND CINNAMIC ACID Wishulada Injumpa, Numpon Insin Sutida Jansod, Praput Thavoryutikarn, Wanwisa Janrungroatsakul, Wanlapa Aeungmaitrepirom, Thawatchai Tuntulani Nattawut Yuntawattana, Pimpa Hormnirun 194-196 197-200 201-204 Vithawas Tungjitgusongun, Ekasith Somsook 205-207 Mareeya Hemman, Chaveng Pakawatchai, Saowanit Saithong , Sujittra Youngme Sirinart Chooset, Anob Kantacha, Arunpatcha Nimthong, Sumpun Wongnawa Phatthareeya Suriya, Ratchadaporn Puntharod 208-210 Uthaiwan Injarean, Pipat Pichestapong, Yoreeta Marnchareon, Sarin Cheephat, Boonnak Sukhummek PREPARATION OF BaZr1-xYxO3-BASED PROTON Suttiruk Salaluk, Apirat CONDUCTING ELECTROLYTE USING TEALaobuthee, Chatchai 217-220 SYNTHESIS OF CALCIUM SILICATE FROM SHELL OF POMACEA CANALICULATA AND RICE HUSK ASH BY MECHANOCHEMICAL METHOD EQUILIBRIUM EXTRACTION OF URANIUM AND THORIUM MIXTURES IN 4 M HNO3 WITH 5 AND 10% TBP/KEROSENE 211-213 214-216 221-224 479 564 590 613 METAL PRECURSOR BY THE SOL-GEL METHOD DEVELOPMENT OF IMPROVED IRON CHELATORS ONE-POT SYNTHESIS OF CuO/ZnO NANOSTRUCTURE WITH DISCRETE CuO NANOPARTICLES ON ZnO HEXAGONAL PLATE OPTICAL SENSING PROPERTIES OF PLASTICIZED POLYMERIC MEMBRANE INCORPORATING N,N'ETHYLENEBIS(SALICYLIMINE) AS TRANSITION METAL ION-SELECTIVE IONOPHORE PREPARATION OF PROTIC IONIC LIQUID/POLYVINYLPYRROLIDONE COMPOSITES WITH ENHANCED HYDROPHOBICITY Veranitisagul, Panitat Hasin and Nattamon Koonsaeng Filip Kielar 225-228 Karnrat Hongpo, Karaked Tedsree 229-232 Jiraporn Pandoidan, Phetlada Kunthadee 233-235 Nuttakarn Moolthong, Natkritta Maipul , Phawit Putprasert 236-238 166 PREPARATION OF CRYSTALLINE NANOSEEDS OF BEA STRUCTURETO INDUCE FORMATION OF ZEOLITE BETA Siriluck Tesana and Aticha Chaisuwan* Department of Chemistry, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok, 10330, Thailand *E-mail:[email protected], Abstract: Crystalline nanoseeds were successfully synthesized using mesoporous SBA-15 as silica source, aluminium isopropoxide as aluminium source, and tetraethylammonium hydroxide as organic template. The TEAOH/SiO2/H2O mole ratio of 0.40/1/7.5 was used. The starting mixture was sonicated thoroughly prior to crystallization in an autoclave under autogenous pressure at 135°C for 48 hours. The product was characterized by XRD, N2 adsorption and SEM techniques. The XRD results presented complete phase transformation from SBA-15 to crystalline seeds. The SEM image showed uniform shape and size of nanoseeds with the average size of approximately 160 nm. Nitrogen adsorption data showed the characteristic behavior of microporous nanoseeds having specific surface area of 702 m2/g. A small amount of calcined crystalline nanoseeds was used successfully as a structure directing agent in the synthesis of highly thermal stable zeolite beta. It was found that the structure of zeolite beta was formed under hydrothermal conditions. In the absence of the crystalline nanoseeds, an amorphous phase was found with a trace amount of zeolite Na-P1 but zeolite beta was not obtained. 1. Introduction Zeolite beta [1-2]has a three dimensional channel system with 12-membered ring pore openings. It has been widely used in several catalytic reactions due to its large micropore volume, unique pore structure and high specific surface area [3-6]. Zeolite beta was usually synthesized by hydrothermal method using tetraethylammonium hydroxide (TEAOH) as structure directing agent or template to shorten crystallization time and to obtain nanocrystals. Unfortunately, the structure of zeolite beta always partially collapses during the combustion of organic templatein order to empty pores and make the zeolite available for applications[7-8].There have been rare reports about the synthesis of zeolite beta in the absence of organic template. In 2008, Xie and coworkers reported the preparation of zeolite beta without organic template[9]; nevertheless, zeolite beta could not be obtained in the absence of calcined zeolite beta as seeds. The synthesis of zeolite beta via addition of inorganic seeds has been attempted by several groups [9-12]. The synthesis of aluminum-rich zeolite beta (Si/Al ratios of 3.9-6.2) was carried out by adding assynthesized zeolite beta as seeds which contained organic template [10]. Among various inorganic cations, only sodium ions provided structure of zeolite beta with the crystal size around 400 nm. Mordenite Tel. +66 2218 7619 was thermodynamically more stable than zeolite beta but in the presence of seeds, zeolite beta phase was kinetically favored [11-12]. To obtain pure zeolite beta, seeds were needed to initiate crystal growth of zeolite beta phase prior to nucleation of mordenite phase. The crystallization of zeolite beta proceeded on the surface of seeds. Crystallinity of zeolite beta was also affected by types of seeds [8]. From our experience, the exothermic combustion of organic template at high temperature is believed to cause aluminium leaching from the zeolite framework to its surface, resulting in the decrease of its crystallinity [3]. To overcome the degradation in zeolite structure, the organic template-free synthetic route has been attempted using our on-site prepared zeolite beta nanoseeds to induce the structure of zeolite beta. 2. Materials and Methods 2.1 Chemicals Tetraethylorthosilicate (Fluka, 98.0 wt%), PluronicP123 (Aldrich), hydrochloric acid (Merck, 37 wt%), tetraethylammonium hydroxide (Fluka, 40 wt%), aluminium isopropoxide (Merck, 99.8 wt%), fumed silica (SiO2,Aldrich, 0.007 µm), sodium aluminate (Riedel-de Haën), and sodium hydroxide (Merck,99 wt%) were used as purchased. 2.2 Synthesis SBA-15 silica was prepared following the method described in the literature [13].Tetraethylorthosilicate was acidic hydrolyzed in the presence of Pluronic P123 and 2M hydrochloric acid at 40°C before crystallization at 100°C for 48 hours. After washing and drying at 100 °C, SBA-15 obtained was calcined at 550°C for 5hours. Aluminium isopropoxide was dissolved in an aqueous solution of 30 wt% tetraethylammonium hydroxide. The resulted solution was added drop-wise to calcined SBA-15 with vigorous agitation. The gel mixture containing Al2O3: TEAOH: SiO2: H2O mole ratio of 0.008: 0.40:1.0:7.5 was crystallized at 135 °C for 48 hours.The fine precipitate was centrifuged, washed and dried at 110 °C before the removal of organic template via calcination at 550 °C for 5 hours. The calcined crystalline nanoseeds were used as structure directing agent for the synthesis of highly thermal stable zeolite beta by modifying the organic template-free synthetic Pure and Applied Chemistry International Conference 2015 (PACCON2015) 167 2.3 Characterization X-ray powder diffraction (XRD) patterns were collected using Rigaku D/MAX-2200 Ultima-plus instrument with Cu Kα radiation source (40kV, 30mA) over 2θ range from 0.7° to 5.0° for SBA-15 and 5.0° to 40.0°for crystalline nanoseeds.Nitrogen adsorptiondesorption experiments of calcined samples were performed at 77 K on a BEL Japan, BEL-SORP mini II nitrogen adsorptometer. The specific surface area was determined using the BET method. The distribution data of micropore sizes were analyzed by the MP-plot method. The particle morphology was determined by a JEOL JSM-6480 LV scanning electron microscope (SEM). 3. Results and Discussion Intensity (arbitrary unit) The XRD patterns of as-synthesized and calcined SBA-15 samples are shown in Figure 1. They are similar to the typical pattern of hexagonal structure of SBA-15 [13-14]. Three well-resolved characteristic peaks observed at 2θ of 0.86°, 1.46° and 1.68° wereassigned to (100), (110) and (200) lattice planes, respectively. After the removal of the organic template at 550 °C for 5 hours, all peaks shifted to higher angle by 0.12°, indicating smaller d-spacing value which is resulted from the unit cell contraction. 2,000 cps (B) (A) 2 Theta (degree) Figure 1 XRD patterns of (A) as-synthesized and (B) calcined SBA-15. From Bragg’s theory, nλ = 2dsinθ, d-spacing is inversely proportional to 2θ. The peak intensities of calcined SBA-15 silica without the organic template are obviously about two times of those belonging to the as-synthesized sample. This phenomenon is normal for porous material synthesized by using an organic template as the structure directing agent. The nitrogen adsorption-desorption isotherms of calcined SBA-15 as shown in Figure 2 can be assigned to Type IV which is a characteristic pattern of mesoporous materials. The SBA-15 sample presented BET specific surface area of 740 m2g-1 and pore volume of 1.13 cm3g-1. SEM images of calcined SBA15 in Figure 3 illustrate bundles of rope-like particles with the average size of particles 39.5 µm. Volume adsorbed (cm3/gSTP) route reported by Zhang and coworkers[8]. A solution containing 3.60 g sodium hydroxide and 0.84 g sodium aluminate in 87.25 g deionized water was mixed with 8.31 g fumed silica with agitation. To the milky gel mixture, calcined crystalline nanoseeds were added at the amount of 2.0 wt% of silica. The whole mixture was transferred into an autoclave and heated in an oven at 130 °C for 5 days. After filtration, washing and drying in an oven at 100 °C, the solid product was characterized for its structures and pore properties. Relative pressure (P/P0) Figure 2 Nitrogen adsorption-desorption isotherms ofcalcined SBA-15 silica. Crystalline nanoseeds were synthesized from onsite-prepared SBA-15 silica by incipient wetness impregnation with the template solution of TEAOH followed by crystallization at 135 °C for 48 hours. The XRD patterns of the as-synthesized and the calcined crystalline nanoseeds are shown in Figure 4. The XRD pattern of the as-synthesized sample was similar to the typical one of zeolite beta with the highest peak located at 2θ of 22.5°. The broad peak at 2θ of 7.68°is resulted from the convolution of peaks due to the concurrence of zeolite beta polymorph A (2θ = 6.98° and 7.74°) and polymorph B (2θ = 7.34° and 8.31°) [15]. After calcination at 550 °C for 5 hours, the XRD peak positions are unchanged but the intensity of the peak at 2θ of 22.5° decreases to about one half due to the partial decomposition of zeolite structure. No peaks are observed at 2θ below 5° (not shown). It can be concluded that phase transformation from SBA-15 to the crystalline nanoseeds of BEA structure can be accomplished under the reported experimental condition. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 168 15 kV x1,000 10 µm (A) 15 kV x5,0005 µm (B) Volume adsorbed (cm3/gSTP) The behavior of mesoporous system is not observed which is correspondent to the XRD result. From BET calculation, a specific surface area of 702 m2g-1 and a micropore volume of 0.37 cm3g-1 were found. The pore size distribution of the crystalline nanoseeds was found in a micropore range with an average pore size of 0.6 nm, a typical value for zeolite beta [16-17].The SEM image of crystalline nanoseeds presents a uniform shape of spheres with an average particle size of 160 nm as shown in Figure 6. Relative pressure (P/P0) Figure 5 Nitrogen adsorption-desorption isothermsofthe crystalline nanoseeds. Intensity (arbitrary unit) Figure 3 SEM images of calcined SBA-15 (A)1,000X magnification and (B) 5,000X magnification. 500 cps (B) 20 kV x50,000 0.5µm (A) 2 Theta (degree) Figure 4 XRD patterns of (A) the as-synthesized and (B) the calcined crystalline nanoseeds. The nitrogen adsorption-desorption isotherms of the crystalline nanoseeds as illustrated in Figure 5 can be assigned to Type I which is typical for micropores. Figure 6 SEM image of the calcined crystalline nanoseeds. Instead of organic template, a small amount of the calcined crystalline nanoseeds was used as a structure directing agent in the synthesis of zeolite beta in this project. The XRD patterns of solid samples synthesized in the absence and presence of crystalline nanoseeds are illustrated in Figure 7. Without crystalline nanoseeds, zeolite beta was not formed and Pure and Applied Chemistry International Conference 2015 (PACCON2015) 169 the solid product was composed of an amorphous phase and a trace amount of zeolite Na-P1. With the addition of nanoseeds, the product shows the characteristic XRD peaks of zeolite beta. After the calcinations at 550°C for 5 hours, little decrease in intensity of the peak at 2θ of 22.5° was observed. This is a good sign indicating the thermal stability of zeolite beta product. This study indicates that the zeolite beta prepared via organic free route exhibits more thermal resistance than those prepared by the conventional organic template route. This is a benefit of the use of zeolite beta in industry because most zeolite catalysts have to be activated at elevated temperatures. 3500 3000 500 cps Intensity (arbitrary unit) 2500 (C) 2000 1500 (B) 1000 500 (A) 0 5 10 15 20 25 30 35 40 2 Theta (degree) References [1] Auerbach, S.M., Carrado, K.A. and Dutta, P.K., 2003, Handbook of Zeolite Science and Technology, Marcel Dekker, USA. [2] Baerlocher, Ch., McCusker, L.B. and Olson, D.H., 2007, Atlas of Zeolite Framework Types, Elsevier B.V., Netherlands. [3] Wanchai, K. and Chaisuwan, A., 2013, Chem. Mat. Res., 3, 31-41. [4] Serafim, H., Fonseca, I.M., Ramos, A.M., Vital, J. and Castanheiro, J.E., 2011, Chem. Eng. J., 178, 291-296. [5] Siffert, S., Gaillard, L. and Su, B.-L., 2000, J. Mol. Catal. A: Chem., 153, 267-279. [6] Chen, N.Y., Garwood, W.E., Huang, T.J., Le, Q.N. and Wing, S.S., 1990, US Pat.4,919,788. [7] Otomo, R., Yokoi, T., Kondo, J.N. and Tatsumi, T., 2041, Appl. Catal., A, 470, 318-326. [8] Zhang, H., Xie, B., Meng, X., Muller, U., Yilmaz, B., Feyen, M., Maure, S., Gies, H., Tatsumi, T., Bao, X., Zhang, W., Vos, D.D. and Xiao, F.S., 2013, Micropor. Mesopor. Mater., 180, 123-129. [9] Xie, B., Song, J., Ren, L., Ji, Y., Li, J. and Xiao, F.S., 2008, Chem. Mater., 20, 4533-4535. [10] Majano, G., Delmotte, L.,Valtchev, V. and Mintova, S., 2009, Chem. Mater., 21, 4184-4191. [11] Kamimura, Y., Chaikittisilp, W., Itabashi, K., Shimojima, A. and Okubo, T., 2010, Chem. Asian J., 5, 2182-2191. [12] Kamimura, Y., Tanahashi, S., Itabashi, K., Sugawara, A., Wakihara, T., Shimojima, A. and Okubo, T., 2011, J. Phys. Chem., 115, 744-750. [13] Zhao, D., Feng, J., Huo, Q., Melosh, N., Fredrickson, G.H., Chmelka, B.F., Stucky, G., 1998, Science, 279, 548-552. [14] Thielemann, J.P., Girgsides, F., Schlögl, R., Hess, C., 2011, Beilstein J. Nanotechnol., 2, 110-118. [15] Sagarzazu, A. and González, G., 2013, Mater. Chem. Phys., 138, 640-649. [16] Ba´rcia, P.S., Silva, J.A.C., Rodrigues, A.E., 2005, Micropor. Mesopor. Mater., 79, 145-163. [17]Mohammadi-Manesh, H., Tashakor, S., Alavi, S., 2013, Micropor. Mesopor. Mater., 181, 29-37. Figure 7XRD patterns of the as-synthesized solid samples (A) in the absence, (B) in the presence of crystalline nanoseeds and the calcined sample (C) at 550°C for 5 hours. 4. Conclusions In summary, crystalline nanoseeds of BEA structure were synthesized from mesoporous SBA-15 silica in the presence of aluminium isopropoxide and tetraethyl-ammonium hydroxide by crystallization of the starting mixture at 135 °C for 48 hours. High crystallinity, large specific surface area and uniform spherical nanoseeds could be achieved. The highly thermal stable zeolite beta catalyst was formed in the presence of a small amount of crystalline nanoseeds. In the absence of nanoseeds, the synthesis of zeolite beta was unsuccessful. Therefore, it can be concluded that the crystalline nanoseeds play an important role as the structure directing agent in zeolite beta formation. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 170 A COLORIMETRIC SENSOR BASED ON 3,5-DIHYDROXYTOLUENE AND 4-NITROPHENYL FOR ANION Paengkwan Jansukra1, Apisit Songsasen1, Thawatchai Tuntulani2, Boontana Wannalerse1* 1Department * of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand 2Supramolecular Chemistry Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok, 10330, Thailand Author for correspondence; E-Mail: [email protected], Tel. +66 25625555 ext. 2203, Fax. +66 25793955 Abstract: 2,2′-(5-Methyl-1,3-phenylene)bis(oxy)bis(N-(4nitrophenyl)acetamide), L1, has been synthesized and explored its properties as a colorimetric sensor. Interactions of receptor L1 with various anions are investigated by using 1H NMR and UV–vis spectroscopy. From 1H NMR studies in DMSO, the signal of NH protons of receptor L1 was found at 10.65 ppm. These protons disappeared after addition of anions (fluoride, acetate, phosphate and benzoate) via deprotonation process. Moreover, the aromatic protons of receptor L1 showed the upfield shift due to enhancement of negative charges in the system. From UV–vis titration in DMSO, the absorption at 328 nm of receptor L1 gradually decreased upon the increment of anions. In the case of fluoride and acetate, a respective isosbestic point and new absorption band were observed at 386 nm and 447 nm for fluoride ion and at 400 nm and 443 nm for acetate ion. The solution color of receptor L1 in DMSO changed from pale yellow to orange and dark yellow in the presence of fluoride and acetate ions, respectively. These results indicated that receptor L1 underwent the charge transfer process upon interacting with anions. The receptor L1 is highly selective to fluoride ion over other anions. The ratio of 1:1 complex between receptor L1 and fluoride ion was identified by Job’s method. 1. Introduction Anions play essential roles in the biological fields, medical systems including environmental processes [1-3]. In addition, anions can be used as indicator for predicting the state of the disease. Fluoride and acetate ions are vital reactive ions in biological systems. Both of them are employed in treatment of health problems such as hypnotics and cockroach poisons. When they reach extreme levels, they can contaminate water and soil. Fluoride also causes diseases such as fluorosis and irregular bone arrangement [4-6]. Basically, sensor systems are composed of two units. One is the anion binding unit and another unit is signalling unit [7]. Both parts are commonly either linked covalently or associated with noncovalent interaction [8]. The design and synthesis of anion receptors have used functional groups such as amide [9], urea/thiourea [10-12] and hydroxyl groups [13] for anion binding sites. Amide moieties (NH group) are the most common unit used in anion receptors due to excellent hydrogen bond donors of the NH groups for anionic guests. In this work, we have designed a new receptor L1 based on 3,5dihydroxytoluene and 4-nitrophenyl. Moreover, receptor L1 is selectively bound to F− and CH3COO−. The complexation between receptor L1 and various anions is investigated by using 1H-NMR spectroscopy and UV-vis spectroscopy. 2. Experimental 2.1 Materials All reagents for synthesis obtained commercially were used without further purification. Column chromatography was performed using silica gel (70230 mesh). In the titration experiment, all anions were added in the form of tetrabutylammonium (TBA) salts which were purchased from Sigma-Aldrich Co. 2.2 Apparatus 1 H NMR spectra were obtained on 400 MHz NMR spectrometer. Elemental analysis (CHNS/O) was performed on Thermo Scientific TM FLASH 2000. UVvis spectra were recorded on Shimadzu spectrophotometer. MS was carried out on Agilent 1100 Series LC/MSD Trap. Infrared spectra (4000-400 cm-1) were obtained by a Perkin Elmer system 2000 Fourier transform infrared spectrometer. 2.3 UV–vis titration studies The sensing properties of receptor L1 toward F−, Cl−, Br−, CH3COO−, C6H5COO− and H2SO4− (as tetrabutylammonium salts) were investigated by UV– vis spectroscopy in DMSO. Stock solutions of receptor L1 and anions were prepared by dissolving in DMSO (5.0×10−5 M). UV–vis titrations were performed with steady concentration of receptor L1 and increasing concentration of anions. 2.4 Synthesis The synthesis of receptor L1 was shown in Scheme 1. 2-Chloro-N-(4-nitrophenyl)acetamide, (1) was synthesized according to literature [14] with minor modifications. 4-Nitroaniline (1.0 g) and triethylamine (2.28 mL) in dichloromethane (3 mL) were stirred under N2 for 30 min. Then, a solution of 2chloroacetylchloride (1.3 mL) in dichloromethane (2 mL) was added dropwise. The reaction mixture was kept stirring until the product was formed as a solid (24 h). The reaction mixture was extracted with water and dichloromethane. The combined organic phase was washed with brine, and dried with anhydrous Na2SO4. After the solvent was removed, the residue was purified by column chromatography (silica gel, dichloromethane) to give a light yellow solid of 1 (0.84 g, 84%). mp:187.6°C. 1H NMR (400 MHz, Pure and Applied Chemistry International Conference 2015 (PACCON2015) 171 DMSO-d6, ppm): δ10.87 (s, 1H,-NH), 8.25 (d, 1H, ArH), 7.85 (d, 1H, ArH), 4.33 (s, 2H, -CH2); FT-IR (KBr/cm-1) ʋ: 3277 (N-H), 1689 (C=O), 1501, 1341 (N-O), 748(C−Cl). MS: m/z calcd for C8H7ClN2O3Na+ ([M-Na+]), 237.0; found, 237.5. The receptor L1 was prepared from the following procedure. 3,5-Dihydroxy-toluene (1.00 g) and potassium carbonate (2.0 g) were dissolved in 20 mL of acetonitrile under N2 atmosphere. Compound 1 (2.5 g) and sodium iodide in acetonitrile was added dropwise. The mixture was stirred and refluxed for 16 h. The reaction mixture was extracted with water and dichloromethane and washed with water. The combined organic phase was dried with anhydrous Na2SO4. After the solvent was removed, the residue was purified by column chromatography (silica gel, dichloromethane and ethyl acetate = 9:1) to give a pale yellow solid of L1 (0.54 g) in a yield of 54%. mp: 250.7°C. 1H NMR (400 MHz, DMSO-d6, ppm): δ 10.65 (s, 1H,-NH), 8.20 (d, 1H, ArH), 7.89 (d, 1H, ArH), 6.47 (t, 1H, ArH), 4.74 (s, 2H, -CH2), 2.25 (s, 3H, -CH3); 13C NMR (DMSO-d6, ppm): 167.54, 158.72, 144.55, 142.47, 139.93, 124.89, 119.28, 108.44, 99.00, 67.11, 21.37; FT-IR (KBr/cm-1) ʋ: 3383 (N-H), 1709 (C=O), 1545,1341 (N-O). MS: m/z calcd for C23H20N4O8-H+ ([M-H+]), 481.1; found, 481.5. Anal. Calcd for C23H20N4O8: C 57.50; H 4.20; N 11.66; Found: C 57.52; H 4.24; N 11.65. receptor L1 the color change from pale yellow to orange and intense yellow were observed respectively, as shown Fig.1. These processes occur via charge transfer process [15]. a b c Figure 1. Color changes of receptor L1 (5×10-5 M) in DMSO on addition of 4 equiv. of various anions: receptor L1 (a), F− (b) and CH3COO− (c) 3.1 1H NMR studies 1 H NMR spectra of receptor L1 upon addition of various anions were carried out in DMSO-d6, as shown in Fig.2. The receptor L1 exhibited a sharp signal of NH amide protons at 10.65 ppm in the spectrum. The NH protons of L1 located at the lower downfield region due to the hydrogen bonding interaction between NH protons (amide group) and DMSO in the solution. Upon addition of acetate, benzoate, dihydrogen phosphate and fluoride ions, the NH amide protons at 10.65 ppm disappeared. Moreover, the aromatic protons of receptor L1 moved to upfield shift due to the enhancement of electron density at aromatic region. These results indicated that the interaction between receptor L1 with CH3COO−, C6H5COO−, H2SO4− and F− involved the formation of hydrogen bonding and deprotonation processes [16]. In the presence of bromide and chloride, the NH protons slightly shifted to downfield because of weak hydrogen bonding interaction in Fig. 2C and 2D. Scheme1. Synthesis of receptor L1 3. Results and discussion The colorimetric sensing and sensitivity of receptor L1 (5×10-3 M) toward various anions such as F−, Cl−, Br−, CH3COO−, C6H5COO− and H2SO4− (tetrabutylammonium salt) are investigated. In DMSO solutions of receptor L1, upon adding 4 equiv. of Cl− and Br− anions, the solution of L1 did not display in any color changes. In the case of C6H5COO− and H2SO4−, the color of solution L1 changes from pale yellow to light yellow. However, upon addition of F−and CH3COO− with receptor L1 to the solution of Figure 2. 1H NMR spectra of receptor L1 (A) in DMSO-d6 (5 x 10-3 M) upon addition of 4 equivalent of F− (B), Cl− (C), Br− (D), CH3COO− (E), C6H5COO− (F) and H2SO4− (G). Pure and Applied Chemistry International Conference 2015 (PACCON2015) 172 Figure 3. UV-vis absorption spectra of receptor L1 (5×10−5 M) in DMSO upon addition of (a) F− and (b) CH3COO− (0 to 20 equivalent). 3.2 UV-vis studies The binding abilities of receptor L1 with various anions (F-, Cl-, Br-, CH3COO-, C6H5COO− and H2SO4-) were examined by using UV–vis spectroscopy in DMSO at room temperature. The receptor L1 displayed strong absorption band at 328 nm. Upon the addition 0-20 equiv. of fluoride ions, the absorption band of receptor L1 gradually decreased and induced a new absorption band at 447 nm and an isosbestic point at 386 nm. In case of acetate ions, the receptor L1 displayed a new absorption band at 443 nm and an isosbestic point at 400 nm, as shown in Fig. 3a and 3b. These results suggest that the formations of the complex between receptor L1 and fluoride ion and acetate ion occur under the internal charge transfer transition. However, the addition of Br−, Cl−, C6H5COO− and H2SO4− into the solution of receptor L1 would give slight decrements of the absorption band at 328 nm in the spectra. The ratio of complexation between receptor L1 and fluoride ion was confirmed by Job's method, as shown in Fig. 4. The maximum absorption appeared at the 0.50 mole fraction of [receptor L1]/ ([receptor L1] + [F−]), indicating a 1:1 formation of receptor L1 and fluoride ion. From the UV–vis absorption titrations, the association constants of the anion complexes of receptor L1 were calculated using Benesi–Hildebrand plot [17]. The association constants, Ka, were listed in Table 1. The selectivity of receptor L1 exhibited in order of CH3COO− > C6H5COO− > H2PO4−. Unfortunately, we could not calculate the association constants between receptor L1 and spherical anions due to the deprotonation process (F− ion) and weak interactions (Br− and Cl− ions). Table 1: Association constants (Ka, M-1) of receptor L1 with various anion in DMSO. anions Ka, M-1 − NDa F − ND Cl − ND Br − CH3COO 5.26×103 − C6H5COO 5.00 ×103 − H2SO4 1.42×102 a The association constant could not be determined. 4. Conclusions We have successfully designed, synthesized and characterized a new colorimetric receptor L1. The receptor L1 utilizes amide NH moieties binding to anions. Through deprotonation process, the receptor L1 could act as naked eye sensors for fluoride and acetate ions. Acknowledgements We would like to thank to the Thailand Research Fund (MRG 5580182), Kasetsart University Research and Development Institute and Department of Chemistry, Kasetsart University and the Center of Excellent for Innovation in Chemistry (PERCH-CIC), Commission on Higher Education, Ministry of Education are gratefully acknowledged for financial support. Figure4. Job’s plot of receptor L1 with fluoride ion. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 173 References [1] Hijji, Y.M., Barare, B., Kennedy, A.P. and Butcher, R., 2009, Sensors and Actuators B: Chem., 136, 297-302. [2] Chauhan, S.M.S., Bisht, T. and Garg, B., 2009, Sensors and Actuators B: Chem., 141, 116-123. [3] Zhang, Y.-M., Lin, Q., Wei, T.-B., Wang, D.-D., Yao, H. and Wang., Y.-L., 2009, Sensors and Actuators B: Chem., 137, 447-455. [4] Lin, Z., Ma, Y., Zheng, X., Huang, L., Yang, E., Wu, C.Y., Chow, T.J. and Ling, Q., 2015, Dyes and Pigments., 113, 129-137. [5] Reena, V., Suganya, S. and Velmathi., S., 2013, Journal of Fluorine Chemistry., 153, 89-95. [6] Gupta, V.K., Singh, A.K., Bhardwaj, S.and Bandi, K.R., 2014, Sensors and Actuators B: Chem., 197, 264-273. [7] Park, J.J., Kim, Y.-H., Kim, C. and Kang, J., 2011, Tetrahedron Lett., 1048, 2759-2763. [8] Park, J.J., Kim, Y.-H., Kim, C. and Kang, J., 2011, Tetrahedron Lett., 52, 3361-3366. [9] Bao, X., Yu, J. and Zhou, Y., 2009, Sensors and Actuators B: Chem., 140, 467-472. [10] Shang, X.-F. and Xu, X.-F., 2009, Biosystems., 96, 165171. [11] Yong, X., Su, M., Wan, W., You, W., Lu, X., Qu, J. and Liu, R., 2013, New J Chem., 37, 1591-1594. [12] Misra, A., Shahid, M. and Dwivedi, P., 2009, Talanta, 80, 532-538. [13] Bao, X. and Zhou, Y., 2010, Sensors and Actuators B: Chem., 147, 434-441. [14] Hernández-Núñez, E., Tlahuext, H., Moo-Puc, R., Torres-Gómez, H., Reyes-Martínez, R., Cedillo-Rivera, R., Nava-Zuazo, C. and Navarrete-Vazquez, G., 2009, Eur J Med Chem., 44 , 2975-2984. [15] Li, Q., Guo, Y., Xu, J. and Shao, S., 2011, J Photochem Photobiol B Biol., 103, 140-144. [16] Gunnlaugsson, T., Glynn, M., Tocci, G.M., Kruger, P.E. and Pfeffer, F.M., 2006, Coord Chem Rev., 250, 3094-3117. [17] Shehadeh, M., Hajar, T., I.W. and Deeb, M., 2007, Jordan J. Chem., 2, 145-153. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 174 SYNTHESIS AND CHARACTERIZATION OF COPPER(II) AND NICKEL(II) COMPLEXES OF HEXAAZA MACROCYCLIC LIGANDS Surachai Kongchoo1, Anob Kantacha2, and Sumpun Wongnawa1* 1 Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand 2 Department of Chemistry, Faculty of Science, Thaksin University, Patthalung, 93110, Thailand * E-mail for Corresponding Author; E-mail: [email protected], Tel. +66 7428 8443, Fax. +66 7455 8841 Abstract: Two new complexes, [CuL](ClO4)2 (1) and [NiL](ClO4)2 (2), of the hexaaza macrocyclic ligand 3,10dioctyl-1,3,5,8,10,12-hexaazacyclotetradecane (L), were synthesized by one-pot condensation of ethylenediamine, formaldehyde, and octylamine in the presence of copper(II) and nickel(II) salts, respectively. The complexes were characterized by elemental analyses (CHN/O), liquid chromatography-mass spectrometry (LC-MS), Fourier-transformed infrared spectroscopy (FT-IR), and UV-Vis spectroscopy. Data from these techniques indicated that each metal ion combined with one ligand L and two perchlorate anions. The structures of these two complexes were then proposed to consist of metal-ion center, Ni(II) or Cu(II), coordinated to a square-planar geometry by four secondary amine nitrogen donors of the hexaaza macrocyclic ligand with two perchlorato ligands to counter ion molecule the square planar geometry. 1. Introduction N-donor atoms hexaaza macrocyclic complexes bearing pendant arms connected by an additional bridge (e.g. -(CH2)n-) at one or two pairs of nitrogen atoms of a macrocycle have received much attention [1] due to possible applications in catalysis [2-3], photocatalytic [4], magnetic properties [5], and antimicrobial activity [6]. Macrocyclic complexes of transition metals, particular, nickel(II) and copper(II), are currently widely used as building blocks for construction of new materials. One of the obvious advantages of such compounds along with their high thermodynamic stability and kinetic inertness is the possibility of synthetically convenient chemical modification of macrocyclic framework using the onepot condensation methods [7]. The metal ions as templates and many macrocyclic ligands have been prepared by the condensation of formaldehyde with amide. Template synthesis of macrocyclic complexes is simple reaction as formaldehyde links between two amine moieties to form methylenediamine linkages (-N-CH2-N-). The methylenediamine linkage is unstable when it contains primary amines, R-NH2, in which R is either aromatic or aliphatic group which can condense with formaldehyde to form a new N-C bond [8]. In this work, we report the syntheses of the complexes of Cu(II) and Ni(II) with hexaaza macrocyclic ligand, and characterizations by spectroscopy techniques. 2. Materials and Methods 2.1 Materials and physical measurements All chemicals were obtained from commercial sources and were reagent grade. Absolute ethanol was used throughout this synthesis. Infrared spectra of solid samples as KBr pellets were recorded on a Perkin-Elmer Spectrum One FT-IR spectrophotometer in the range 4000-400 cm-1. Electronic absorption spectra were obtained on a Shimadzu Lambda-1600 UV-Vis spectrophotometer. Elemental analysis of CHNO was performed using a CE instruments Flash EA 1112 series, Thermo Quest analyzer. Mass spectra were recorded by electro-spray ionization (ESI) technique operating in the positive ion mode, the solution was injected directly in mass spectrometer (Waters micromass). Caution! Perchlorate salts are potentially explosive and should be handled in small quantities. 2.2 Synthesis of [CuL](ClO4)2 (1) To a stirred solution of copper(II) chloride dihydrate (1 mmol) and ethylenediamine (2 mmol) in absolute ethanol added dropwise a solution of formaldehyde (4 mmol) and octylamine (2 mmol) in absolute ethanol (15 mL). The reaction mixture was refluxed for 24 h. The hot solution was filtered, cooled and perchloric acid was added slowly. The precipitate formed was filtered off, washed with absolute ethanol, and dried in air. Yield: ∼75%. Anal. Calc. for C24H54N6O8Cl2Cu: C, 41.72; H, 7.88; N, 12.17; O, 17.78. Found C, 41.45; H, 7.81; N, 12.52; O, 17.88%. 2.3 Synthesis of [NiL](ClO4)2 (2) Complex 2 was prepared similarly to that of complex 1 except that nickel(II) chloride hexahydrate was used instead of copper(II) salt. Yield: ∼50%. Anal. Calc. for C24H54N6O8Cl2Ni: C, 41.92; H, 7.87; N, 12.25; O, 24.68. Found C, 41.62; H, 7.81; N, 12.36; O, 24.74%. 3. Results and Discussion The hexaaza macrocyclic complexes were synthesized in a one-pot condensation from the starting materials: copper(II) chloride dihydrate (or nickel(II) chloride hexahydrate), ethylenediamine, formaldehyde, and octylamine with in molar ratio 1:2:4:2 according to Scheme 1. The powder products Pure and Applied Chemistry International Conference 2015 (PACCON2015) 175 were soluble in organic solvents such as DMSO, MeCN, DMF, and acetone. Unfortunately, all efforts failed to grow single crystal suitable for X-ray crystallography. macrocyclic complexes reported by Sujatha and coworkers [11-12]. Scheme 1. The preparation of 1 and 2 complexes 3.1 FT-IR spectra of 1 and 2 The preliminary investigation of the hexaazamacrocyclic complexes was done from their FT-IR spectra (Figure 1.). The FT-IR of 1 and 2 showed the absence of a strong band in the range 1720-1740 cm-1 assignable to carbonyl group of aldehydic moiety confirming the condensation reaction [9]. However, the both complexes a weak band at 1638 cm-1 was assigned to δ(O-H) of the moisture. The complexes showed the presence of sharp band around 3241 and 3206 cm-1 corresponding to ν(N-H) of the coordinated secondary amine of the 1 and 2, respectively. A medium intensity band appearing in the range 29272857 cm-1 was assigned to ν(sp3 C-H) [10]. In the region 1100 cm-1, splitting to two peaks at 1121-1118 and 1093-1167 cm-1 could be assigned to perchlorate ions. The splitting of this peak clearly explained the presence of coordinated perchlorate. In both complexes, a band seen at 485-471 cm-1 was probably due to the formation of M-N bonds [6]. Figure 2. The mass spectra of 1 Figure 1. The FT-IR spectra of 1 and 2 3.2 Mass spectra of 1 and 2 The electro-spray ionization mass spectra of the perchlorate salts of copper(II) and nickel(II) complexes were studied in positive mode. Complex 1 showed an intense signal of m/z values at 588.3 (100%) and 590.3 (85%) corresponding to [CuL(ClO4)]+ and [CuL(ClO4)-2H]+ (Figure 2.) whereas complex 2 showed peaks at 583.3 (100%) and 585.3 (80%) corresponding to [NiL(ClO4)]+ and [NiL(ClO4)-2H]+ (Figure 3.). Similar type of mass spectra patterns have been observed in hexaaza Figure 3. The mass spectra of 2 3.3 UV-Vis spectra of 1 and 2 The electronic spectra of 1 (Figure 4) showed a broad band at 502 nm consistent with that reported for square planar geometry and, thus, was assigned to the 2 Eg → 2T2g [6]. In general, due to Jahn-Teller distortion Cu2+ complexes give absorption band between 599699 nm [13]. No absorption bands are observed in the Pure and Applied Chemistry International Conference 2015 (PACCON2015) 176 region near UV any complex under study which rules out the possibility of tetrahedral geometry [14]. The electronic spectra of 2 (Figure 5) exhibited two bands at 452 and 625 nm which could be assigned to 3 A2g (F) → 3T2g (F) and 3A2g (F) → 3T1g (P) transitions, respectively [6], for the square planar Ni2+ complex [13]. The electronic spectra found in 1 and 2 were of the d-d transition type similar to those reported by Firdaus and co-workers [15]. 2E g nitrogen atoms of the hexaaza macrocyclic ligand and two oxygen atoms from perchlorate anions. The hexaaza macrocyclic occupies the equatorial sites to form a square-planar geometry leaving the two oxygen atoms (from two perchlorates) at the axial sites to counter ion molecule. The macrocyclic itself contains two each of five- and six-membered rings. A similar structure was presented in previous research [16-18]. 4. Conclusions Copper(II) and nickel(II) complexes have been synthesized by the one-pot condensation reaction. The elemental analyses and LC-MS revealed the stoichiometry and composition while FT-IR and UVvisible spectra confirmed the bonding features and stereochemistry of the hexaaza macrocyclic complexes. → 2T2g Acknowledgements Figure 4. Electronic absorption spectra of 1 This work was supported by the Songklanagarind Scholarship for Graduate Studies from the Prince of Songkla University. References 3A 2g 3A 2g → 3T1g → 3T2g Figure 5. Electronic absorption spectra of 2 From spectroscopic data the structure of both complexes can be proposed as follows (Figure 6.). O O Cl O O H N H N N M N N H N H O O Cl O O Figure 6. The proposed structure for 1 and 2 (M = Cu(II) or Ni(II)) In the proposed structures, the coordination geometry about each metal-ion center, Ni(II) or Cu(II), is square planar composed of four secondary amine [1] Firdaus, F., Fatma, K., Azam, M., Khan, S.N., Khan, A.U. and Shakir, M., 2008, Transition. Met. Chem., 33, 467-473. [2] Salavati-Niasari, M., 2004, J. Mol. Catal. A: Chem., 217, 87-92. [3] Salavati-Niasari, M., 2004, Inorg. Chem. Commun., 7, 963-966. [4] Gokulakrishnan, S., Parakh, P. and Prakash, H., 2012, J. Hazard. Mater., 213-214, 19-27. [5] Kou, H.-Z., Jiang, Y.-B., Zhou, B.C. and Wang, R.-J., 2004, Inorg. Chem., 43, 3271-3276. [6] Husain, A., Nami, S.A.A. and Siddiqi, K.S., 2011, Appl. Organometal. Chem., 25, 761-768. [7] Tsymbal, L.V., Andriichuk, I.L., Lampeka, Y. D. and Pritzkow, H., 2010, Russ. Chem. Bull., 59, 1572-1581. [8] He, Y., Kou, H.-Z., Li, Y., Zhou, B.C., Xiong, M. and Li, Y., 2006, Inorg. Chem. Commun., 6, 38-42. [9] Shakir, M., Azim, Y., Chishti, H.T.N., Begum, N., Chingsubam, P. and Siddiqi, M.Y., 2006, J. Braz. Chem. Soc., 17, 272–278. [10] Raman, N., Raja, J.D. and Sakthivel, A., 2008, J. Chill. Chem. Soc., 53, 1568–1571. [11] Sujatha, S., Balasubramanian, S. and Varghese, B., 2009, Polyhedron., 28, 3723-3730. [12] Sujatha, S., Balasubramanian, S., Varghese, B., Jayaprakashvel, M. and Mathivanan, N., 2012, Inorg. Chim. Acta., 386, 109-115. [13] El-Sherif, A. A., 2009, Inorg. Chim. Acta., 362, 49915000. [14] Patel, M.N., Patel, C.B and Patel, R.P., 1974, J. Inorg. Nucl. Chem. 36, 3868-3870. [15] Firdaus, F., Fatma, K., Azam, M., Khan, S.N., Khan, A.U., and Shakir, M., 2008, Transition. Met. Chem., 33, 467-473. [16] Husain, A., Moheman, A., Nami, S. A.A. and Siddiqi, K.S., 2012, Inorganica Chimica Acta., 384, 309-317. [17] Min, K.S., Park, M.J., and Ryoo, J.J., 2013, Chirality, 25, 54-58. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 177 [18] Han, S., Lough, A.J., and Kim, J.C., 2012, Bull. Korean Chem. Soc., 33, 2381-2384. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 178 Cu(II) AND Zn(II) COMPLEXES OF POLYDENTATE SCHIFF BASE LIGANDS: SYNTHESIS, CHARACTERIZATION, PROPERTIES AND BIOLOGICAL ACTIVITY Abdulaziz M. Ajlouni1∗, Ahmed. K. Hijazi1, Ziyad A. Taha1 and Waleed Al Momani2 1Department of Applied Chemical Sciences, Jordan University of Science and Technology, Irbid 22110, Jordan 2 Department of Allied Medical Sciences, Al Balqa’ Applied University, Jordan *E-mail:[email protected] Tel. : + 962 (0) 2 7201000, Fax : + 962 (0) 2 7095123 Abstract: Four Schiff base ligands bearing a 9fluorenylidene unit, L1-L4 where (L1 = N'-(9H-fluoren-9ylidene)-2,4-dihydroxybenzohydrazide, L2 =N'-(9Hfluoren-9-ylidene)thiophene-2-carbohydrazide, L3 =N'(9H-fluoren-9-ylidene)furan-2-carbohydrazide, and L4 =2(9H-fluoren-9-ylidene)hydrazinecarbothioamide, and their [Zn(L)Cl2] and [Cu(L)Cl2] complexes have been synthesized. The characterization and nature of bonding of these complexes were elucidated by elemental analyses, spectral analyses (1H NMR, FTIR), molar conductivity measurements and thermo-gravimetric studies. Analytical and spectral data revealed that L1 coordinates to metal ions by its imine nitrogen atom and the phenolic oxygen atom with a 1:1 stoichiometry. The L2-L4 coordinates to metal ions by their imine nitrogen atom and the carbonyl oxygen atom with the same stoichiometry. Most of the free ligands L1-L4 and their complexes exhibit antibacterial activities against a number of pathogenic bacteria. The activities of metal complexes are found to be higher than those of the free ligands. 1. Introduction Schiff bases are some of the most widely used organic compounds. They have been shown to exhibit a broad range of biological activities, including, antifungal, antibacterial, antimalarial, antiproliferative, anti-inflammatory, antiviral, and antipyretic properties [1]. Imine or azomethine groups are present in various natural, natural-derived, and non-natural compounds. The imine group present in such compounds has been shown to be critical to their biological activities [2]. Fluorenone Schiff bases have a potential application and biological activity in many therapeutic areas such as antifungal and antitumor activity [3]. The hydrazones metal complexes such as copper, zinc, lanathanum and silvers complexes derived from (9Hfluorene-9-ylidine)-thiosemicarbazide, have also shown many therapeutic activities [4]. In this work, different hydrazones containing fluorenone Schiff bases L1-L4, and their Cu(II) and Zn(II) complexes have been synthesized and characterized by many physical and spectroscopic techniques including elemental analyses, spectral analyses (1H NMR, FT-IR), molar conductivity, and thermogravimetric analysis. The biological activities of these compounds were investigated by evaluating the antibacterial behaviors against various pathogenic bacterial strains using agar diffusion method. H N O N H N N HO O S HO O L2 L1 H N H N S N O N H2N L3 L4 Figure 1. Structures of the Schiff base ligands L1-L4 2. Materials and Methods Experimental All solvents used were of analytical grade purchased from Aldrich Chemical Company and were used without further purification. Copper (II) chloride dihydrate CuCl2·2H2O and anhydrous zinc (II) chloride ZnCl2 were purchased from Sigma Aldrich Chemical Company and used as received. Acid hydrazides and 9H-fluoren-9-one were purchased from Merck Schuchardt. The metal ions were determined by EDTA titration using xylenol orange as an indicator [5]. Carbon, nitrogen and hydrogen analyses were performed using a Vario EL elemental analyzer. Infrared spectra (4000–400 cm−1) were obtained with KBr discs on a JASCO FT-IR model 470 spectrophotometer. 13C NMR and 1H NMR spectra of the complexes were recorded on a Bruker AVANCE400 MHz NMR spectrometer. Spectra were taken in DMSO-d6 using TMS as an internal reference. The molar conductance measurements were carried out in DMF using a WTW LF 318 model conductivity meter equipped with a WTW Tetracon 325 conductivity cell. Thermal analyses were performed on a PCT-2A thermo balance analyzer operating at a heating rate of 10 ºC /min in the range of ambient temperature up to 700 ºC under N2. General procedure for synthesis of hydrazones A mixture of the respective acid hydrazides (1 mmol) and fluoren-9-one (1 mmol) in ethanol (30 ml) in the presence of two drops of acetic acid was refluxed for 4 h. Upon cooling L1-L4 were obtained as crude products. The products were collected by Pure and Applied Chemistry International Conference 2015 (PACCON2015) 179 filtration, washed with cold ethanol, and air-dried. The microcrystalline material obtained was recrystallized from hot ethanol Table 1. 3. Results and discussion Elemental analysis and molar conductivity L1:N'-(9H-fluoren-9-ylidene)-2,4dihydroxybenzohydrazide, m.p. 214-216⁰C, 1H-NMR (DMSO-d6, δ, ppm): 11.93 (s, 2H, OH); 11.35 (s, 1H, NH), 8.41–6.18 (m,11H, C–H Aromatic). 13C NMR (100 MHz, (DMSO-d6, δ, ppm)): 165.3 (C=O). 153.4 (C=N), 162.0 (2C-OH), 133,4, 132.4, 130.6, 128.9, 127.6, 126.5, 125.8, 125.3, 124.9, 124.8, 123.9, 122.4, 118.2, 117.8. 112.8. L2:N'-(9H-fluoren-9-ylidene)thiophene-2carbohydrazide. m.p. 178-182⁰C, 1H-NMR (DMSO-d6, δ, ppm): 10.85 (s, 1H, NH), 8.47–7.28 (m,11H, C–H Aromatic). 13 C NMR (100 MHz, (DMSO-d6, δ, ppm)): 170.6 (C=O),155.2 (C=N), 133,4, 132.4, 130.6, 128.6, 127.6,126.5, 125.8, 125.3, 124.9, 124.8, 123.9, 122.4, 118.2, 117.8. 112.2 L3: N'-(9H-fluoren-9-ylidene)furan-2-carbohydrazide, 173-177⁰C, 1H-NMR (DMSO- d6, δ, ppm): 10.85 (s, 1H, NH), 8.47–7.28 (m,11H, C–H Aromatic). 13 C NMR (100 MHz, (DMSO-d6, δ, ppm)): 170.6 (C=O),155.2 (C=N), 133,4, 132.4, 130.6, 128.6, 127.6, 126.5, 125.8, 125.3, 124.9, 124.8, 123.9, 122.4, 118.2, 117.8. 112.2 L4:2-(9H-fluoren-9-ylidene)hydrazinecarbothioamide, m.p.155-157⁰C, 1H-NMR (DMSO-d6, δ, ppm): 11.24 (s, 2H, NH2), 10.78 (s, 1H, NH2), 8.57–7.48 (m,11H, C–H Aromatic). 13 C NMR (100 MHz, (DMSO-d6, δ, ppm)): 182.6 (C=S). 155.8 (C=N), 147.3, 134,4, 131.4, 130.6, 128.6, 127.6, 125.8, 124.9, 124.3, 123.9, 122.4, 119.5. Synthesis of the complexes A 1.0 mmol of a ligand was dissolved in 25 mL methanol. To this solution, a 25 mL methanol solution of 1.0 mmol CuCl2 was added dropwise. The reaction mixture was stirred for 4 hours at room temperature. The precipitated complex was separated from the solution by filtration, purified by washing several times with cold methanol, and then dried for 24 hours under vacuum at room temperature. The other complexes were prepared following the same procedure. Table 1 lists the elemental analysis data, and molar conductivities of L1-L4 and their metal complexes. All of metal complexes are air stable nonhygroscopic powder, partially soluble in water and most organic solvents. The elemental compositions (C, H, N and metals) of the L1-L4 and the corresponding metal complexes are relatively close to those calculated based on molecular formulae proposed. The molar conductivity data for all complexes in DMF solution at room temperature are in the range of "18–50" S cm2 mol-1. This range of conductivity is very common for non-electrolyte solutions [6], and indicates that the anions are directly bonded to the metal ions rather than exist as free ions in the solution or counter anion in the solid lattice. Infrared spectral analysis. The most diagnostic infrared spectral bands of L1-L4 and their metal complexes are listed in table 2. The IR spectrum of L1 reveals bands at 3473, 1664, 1627 and 1279 cm-1, which are assigned to ν(OH), ν(C=O), ν(C=N), and ν(Ar–O) respectively. Upon complexation with Zn(II) and Cu(II), the C=N bands shift to 1604 and 1611 cm−1, respectively, which indicates that the metal is coordinated to the schiff base via the nitrogen atom of the azomethine group [7]. This was confirmed by the appearance of new bands at 491 and 492 cm-1 related to υ (Zn–N) and υ (Cu–N) [8], respectively. The IR spectrum of the free ligand L1 exhibits a broad band between 3600 and 3200 cm−1 with a maximum at 3473 cm−1 assigned to the stretching frequency of the phenolic hydroxyl substituent υ(O–H) which probably involving an intramolecular hydrogen bonding. Upon complexation with Zn(II) and Cu(II) to form, presumably, [Zn(L1)Cl2] and [Cu(L1)Cl2] complexes, the intensity of the υ (O–H) band increases and the maximum bands (appear at 3473 cm-1 in the free ligand) are shifted to 3491 and 3492 cm−1, respectively. The remain of these bands in the complexes spectra with few shifts show that the hydroxyl oxygen atom is coordinated to the metal center, Zn(II) or Cu(II), without proton displacement. The coordination via the oxygen atom was further supported by the appearance of new bands at 615 and 617 cm−1, which may be assigned for υ (Zn–O) and υ (Cu–O) [9], respectively. Furthermore, the 1H NMR spectrum of the [Zn(L1)Cl2] complex shows the presence of the OH signal at δ 11.93 confirming the IR data. Other IR bands related to υ (NH), υ (C=O), and υ (Ar–O) have been appeared in both free ligand and complex spectra with some shifts due to the change in the environment after complexation [10]. The IR spectra of the Zn(II) and Cu(II) complexes with L2 and L3, display that the Scheme 1. Synthetic Pathway for Compounds L1-L4 Pure and Applied Chemistry International Conference 2015 (PACCON2015) 180 Table 1. Analytical data for the prepared compounds and molar conductance values for metal complexes. C (%) found (calc.) H (%)found N (%)found Metal (%)found S (%)found (calc.) Yield aΛ m 72.08 (72.71) 4.33 (4.27) 8.56 (8.49) 87 50.81 (51.47) 3.10 (3.02) 6.19 (5.99) 14.32 (14.06) 82 18.18 51.78(51.68) 3.01 (3.05) 5.57 (6.02) 13.75 (13.64) 86 19.28 71.48 (71.03) 4.18 (3.97) 9.25 (9.20) 10.32 (10.54) 90 49.33 (49.06) 2.84 (2.74) 6.69 (6.63) 14.61 (14.88) 7.32 (7.28) 85 33.28 48.78 (49.27) 2.71 (2.76) 6.12 (6.38) 14.56 (14.48) 7.38 (7.31) 84 39.75 74.58 (74.99) 4.29 (4.20) 9.80 (9.74) 90 51.54(51.12) 3.01(2.85) 6.68(6.60) 15.11(15.41) 79 34.88 52.69 (52.61) 3.10 (2.90) 6.76 (6.63) 14.20 (15.05) 82 37.87 66.20(66.38) 4.42(4.38) 16.38(16.54) 12.32 (12.66) 93 43.03(43.16) 3.09(2.89) 10.63(10.85) 16.60(16.71) 7.30 (7.23) 75 49.55 43.83(43.36) 3.09(2.90) 10.77(10.79) 16.74(16.35) 8.39 (8.27) 79 48.85 a Λ m: Molar conductance (Ω-1 cm-1 mol-1) of 1 x 10-3 M solution in DMF at room temperature. and the decomposition starts around 300°C and finished around 500°C with υ(C=O) and υ(C=N) bands are shifted to lower one decomposition step, frequencies compared to the free ligands indicating that the carbonyl oxygen atom and the azomethine whereby the complexes decomposed in many stages. nitrogen atoms are involved in the coordination Table The first stage of the decomposition of Zn(L1)Cl2 2. This was further confirmed by the appearance of complex is in the range of 218-333 °C may be to loss new absorption bands between 595-600 and 489-495 of two HCl molecules with a mass loss of 15.09 % cm-1 assigned to υ(M-O) and υ(M-N), respectively which is consistent with the theoretical value (15.24 [11]. The characteristic bands of the aromatic rings in %). The second stage occurs between 333-500 °C with the spectra of respective complexes remain almost a mass loss of 71.13 % may be due to the loss of the unshifted. The above arguments indicate that L2 and organic moiety and is consistent with the theoretical Compound L1 [Zn(L1)Cl2] [Cu(L1)Cl2] L2 [Zn(L2)Cl2] [Cu(L2)Cl2] L3 [Zn(L3)Cl2] [Cu(L3)Cl2] L4 [Zn(L4)Cl2] [Cu(L4)Cl2] Table 2: Major infrared spectral data for the free ligands L1-L4 and their metal complexes (cm-1). Compound L1 [Zn(L1)Cl2] [Cu(L1)Cl2] L2 [Zn(L2)Cl2] [Cu(L2)Cl2] L3 [Zn(L3)Cl2] [Cu(L3)Cl2] L4 [Zn(L4)Cl2] [Cu(L4)Cl2] υ (OH) 3473 3489 3491 - υ (NH) 3206 3341 3353 3200 3222 3227 3220 3219 3220 3200 3215 3216 υ (C=O) 1664 1664 1642 1648 1632 1638 1642 1626 1622 - υ (C=N) 1627 1604 1611 1601 1584 1589 1594 1572 1574 1587 1578 1574 L3 behave as neutral bidentate ligands and the coordination occurs via the carbonyl oxygen and the azomethine nitrogen atom. The IR spectra of the Zn(II) and Cu(II) of L4 complexes show the υ (C=S) and υ (C=N) bands are shifted to lower frequencies compared to the free ligands. Suggesting that (C=S) and (C=N) coordinate with the metal by the sulfur atom and azomethine nitrogen atom Table 2. Thermal studies Thermogravimetric (TGA) and differential thermogravimetric (DrTGA) analyses were carried out for L1-L4. The TGA-DrTGA curves show that ligands L1-L4 are thermally stable in the range of 50-300 °C υ (C-O) υ (C-S) υ (C=S) υ (M-O) υ (M-N) 1279 1256 615 491 1261 617 492 1358 1318 598 489 1320 600 495 592 483 591 481 1409 1385 603 483 value (70.81 %). The last step is the oxidation of metal - give metal- oxide [12]. 1389 603 480 (II) to Antibacterial activity The antibacterial screening data show that the complexes exhibit antimicrobial properties, and the metal chelates exhibit more inhibitory effects than the parent ligands Table 3. All synthesized compounds showed high to moderate antimicrobial activities against the Gram-negative bacteria tested. The highest activities were found against Klebsiella pneumonia. On the other hand, Pseudomonas aeruginosa was found to be resistant to all free ligands L1-L4 and to their complexes. L2 and its metal complexes inhibit most of the tested microorganisms. All synthesized compounds showed moderate, poor, and even non- Pure and Applied Chemistry International Conference 2015 (PACCON2015) 181 Table 3. Antibacterial activities of the free ligands L1-L4 and their metal complexes against test bacteria using agar well diffusion. Gram (− ) bacteria Pm ++ ++ ++ ++ +++ ++ + + + +++ Gram (+) bacteria Sp + + + + + +++ Tested compounds Ec Kp Se Pa Sa En + + + + L1 [Cu(L1)Cl2] ++ +++ + + [Zn(L1)Cl2] ++ +++ + + + ++ ++ + + L2 [Cu(L2)Cl2] ++ +++ +++ ++ + [Zn(L2)Cl2] ++ ++ ++ + ++ ++ ++ L3 [Cu(L3)Cl2] ++ ++ [Zn(L3)Cl2] ++ ++ ++ ++ ++ L4 [Cu(L4)Cl2] ++ +++ ++ [Zn(L4)Cl2] +++ +++ ++ DMSO (-ve control) Oxytetracycline +++ +++ +++ ++ +++ ++ (+ve control) Ec: Escherichia coli; Kp: Klebsiella pneumonia; Pm: Proteus mirabilis; Se: Salmonella enteritidis; Pa: Pseudomonas aeruginosa; Sa: Staphylococcus aureus; Sp: detectible antimicrobial activities against the Gramproviding financial support for this Project (No.2011 positive bacteria tested. /202). The higher activities of the complexes compared to the free ligands may be attributed to chelation, which reduces the polarity of the metal ion by partial sharing of the positive charge with donor atoms of the ligand [13]. This increases the lipophilic character, favouring the permeation through lipid layers of the bacterial membrane. Higher activities observed against the gram negative bacteria can be explained by considering the effect on lipo–polysaccharide (LPS), a major component of the surface of gram negative bacteria [14]. LPS is an important entity in determining the outer membrane barrier function and the virulence of Gram negative pathogens. The free ligands L1-L4 can penetrate the bacterial cell membrane by coordination of the metal ion through oxygen or nitrogen donor atoms to LPS which leads to the damage of the outer cell membrane and consequently inhibits the growth of the bacteria [15]. 4. Conclusions Four hydrazone compounds, L1-L4, containing a fluorenylidene unit and their Zn(II) and Cu(II) complexes were synthesized and characterized by different techniques. The compounds L1-L4 can coordinate to a metal center in a bidentate fashion. Most of the free ligands and the synthesized complexes exhibit antibacterial activities against a number of pathogenic bacteria. The metal complexes show higher activities compared to those of the free ligands. References [1] Fraga, C. and Barreiro, E., 2006, Curr. Med. Chem. 13 167-198. [2] Rollas, S. and Küçükgüzel S¸, 2007, Molecules 12 1910-1939. [3] Narasimhan, B., Kumar, P. and Sharma, D., 2010, Acta Pharm. Sci. 52 169-180 [4] Ajlouni, A., Mhaidat, I., Al Momani, W., Taha, Z,. Al Zouby, M,.; , 2013, Jordan Journal of Chemistry, 8 (4) 225-236. [5] Welcher,F. J. The Analytical Uses of EDTA, Van Nostrand, New York, 1995, p.50. [6] Geary. W., Coord. Chem. Rev., 1971, 81-122. [7] Raman N,; Kulandaisamy A,; Shunmugasundaram A,; Jeyasubramanian K, 2001, Transition Metal Chemistry., , 26 131-135. [8] Sumanta K P, Rojalin S and Vadivelu M 2008 Polyhedron, 27 805 [9] Chakraborty D and Chen E Y-X, 2003, Organometallics, 22 769 [10] Paolucci, G.; Stelluto, S.; Sitran, S., 1985, Inorg. Chim. Acta., , 110, 19–23 [11] Canpolat, E.; Kaya, M., J. 2002, Coord. Chem., , 55, 961-968. [12] Wang, W., Huang, Y., and Tang, N., 2007 Spectrochim. Acta A, 66 1058. [13] Kantouch, A .; El-Sayed A.,2008, Int. J. Biol. Macromol., 43, 451-459. [14] Taha, Z. A.; Ajlouni, A. M.; Al Momani, W.; 2012,." J. Luminescence, 132, 2832-2841. [15] Al Momani, W. M.; Taha, Z. A.; Ajlouni, A. M.; Abu Shaqra,Q. M.;. 2012, Asian Pacific Journal of Tropical Biomedicine, 1-4. Acknowledgements The authors are very grateful to the Jordan University of Science and Technology Research fund for Pure and Applied Chemistry International Conference 2015 (PACCON2015) 182 SOME FIRST ROW TRANSITION COMPLEXES WITH ACETYLACETONATE AND TETRAAZAMACROCYCLIC LIGANDS FOR ANTIBACTERIAL ACTIVITY Tossapon Phromsatit, Supakorn Boonyuen*, Natthakorn Phadugsak and Pornsan Luangsriprech Department of Chemistry, Faculty of Science and Technology, Thammasat University, Pathumthani 12120, Thailand *E-mail: [email protected] Abstract: The complexes with two types of ligands, metal acetylacetonate complexes (M(acac)2 where M = Cu2+ and M(acac)3 where M =Al3+, Mn3+, Fe3+ and Co3+) and metal tetraazamacrocyclic complexes (ML[1] and ML[2], where M = Ni2+, Cu2+ and Zn2+ and L[1] = 5,7,7,12,14,-14 hexamethyl-1 ,4 ,8 ,-1 1 tetraazacyclotetradeca4 ,-1 1 diene perchlorate and L[2] = 7,14-diethyl-5,6,7 ,1 2 ,1 3,-1 4 hexamethyl-1 ,4 ,8 ,1 1 -tetraazacyclotetradeca4 ,-1 1 diene perchlorate) have been synthesized and characterized. The structures of synthesized complexes were confirmed by IR, 1H-NMR, 13C-NMR, UV-Vis spectroscopy. All compounds have been screened for their antibacterial activityusing disc diffusion technique. The microorganism used for antibacterial investigation included Escherichia coli (E. coli) and staphylococcus aureus (S. aureus).All complexes exhibited appreciable activity especially CuL[1] and NiL[1], suggesting a potential to develop for medical applications. 1. Introduction The synthesis and study of macrocyclic complexes, including chelating complexes have undergone tremendous growth in recent years. Their complexation chemistry with a wide variety of metal ions has been extensively studied. For various applications, tetraaza macrocyclic ligands are of special interest, and coordinating side chain may increase the stability of the metal complexes and the selectivity between various metal ions [1 - 3]. The coordination chemistry of square planar metal complexes, involving nitrogen donor ligands, has excited great interest among chemists in recent years due to the catalyst application and relevance to bioinorganic system. The metal complexes with tetraaza macrocyclic ligands and acetyl acetonate ligands are studied. Various biological applications such as antifungal, antibacterial and anticancer activity of synthesized transition metal complexes have been carried out [4 - 6]. The ligands and complexes described in this article have been synthesized and characterized with various physicochemical techniques. Furthermore, antibacterial activities of the ligands and their transition metal complexes have been determined by screening of the compounds against various bacterial strains. The results were compared with standard drugs [7]. 2. Materials and Methods 2.1 Measurement Elemental analysis of C and H were performed on Perkin Elmer (series II) CHNS/O Analyzer. The electronic spectra were recorded on Shimadzu UV-vis spectrophotometer (solution) and Shimadzu UV- spectrophotometer(UV-2600 Series) (solid state). Samples were prepared in quartz cells of 10 mm path length in water (tetraaza macrocyclic complexes), methanol and DMSO (acetyl acetonate complexes), and spectra were recorded at room temperature. The FT-IR spectra were recorded on a Perkin Elmer infrared spectrophotometer (spectrum GX) using the Nujol, NaCl(tetraaza macrocyclic complexes)and KBr pellet technique (acetyl acetonate complexes). 1 H-NMR and 13C-NMR spectra were recorded with a Bruker (FT-NMR advance 400 MHz) spectrometer in chloroform-d using TMS as the internal standard. 2.2 Synthesis of tetraaza macrocycilc ligands and their complexes. The ligands (L[1] and L[2]) were prepared by mixing ethylene diamine (C2H8N2, 6.6 ml, 1 mol.) and methanol (CH3OH, 5 ml) in a beaker and kept in an ice bath (5°C). Then, perchloric acid (HClO4, 12.02 ml,1 mol.) was added (pH=7). Then, a proper ketone was added (acetone, C3H2O for synthesis of ligand L[1], C16H32N4Cl2O8, and ethyl methyl ketone, C4H8O for synthesis of ligand L[2], C22H44N4Cl2O8), and the mixture was kept in the freezer overnight. The mixture was filtered and washed with acetone and dried under vacuum, the white crystals are obtained. (Ligand L[1], 10.3304g, 21.57%, L[2], 9.0251g, 16.03%) Each of methanolic solution of metal-ligands(M= Ni2+, Cu2+, and Zn2+L[1], C16H32N4Cl2O8, 0.4790 g, L[2], C22H44N4Cl2O8, 0.5630 g, 0.001 mol.) was prepared in a round bottom flask, by mixing the solid ligand with methanol (CH3OH, 30 ml). Each ligand solution was reacted with various metal acetate (Ni(OAc)2•4H2O, 0.2487 g, Cu(OAc)2•4H2O, 0.2536 g, and Zn(OAc)2•2H2O, 0.2195 g, 0.001 mol.). Then the mixture was refluxed for 1 hr. The solution was evaporated to concentrate before crystallization. Each metal complex was separately filtered, washed with cool methanol and dried in vacuum. (NiL[1], 0.2693 g, 50.08%, CuL[1], 0.3022 g, 55.09%, ZnL[1], 0.2246 g, 40.21%, NiL[2], 0.2481 g, 39.84%, CuL[2], 0.2590 g, 40.72% and ZnL[2], 0.1312 g, 20.7%). Pure and Applied Chemistry International Conference 2015 (PACCON2015) 183 Ligand L[1]: FT-IR (Nujol, NaCl): 3154.06 (N-H Vibration), 1543.07 (NH2+ str.), 1667.85 (C=N str.). 1 H-NMR (DMSO): δ,ppm. 3.2 (N-H), 2.5(-CH2), 2.1(CH3). 13C-NMR (DMSO): δ, ppm. 44.45 (-CH2), 35.84 (-CH3). Ligand L[2]: FT-IR (Nujol, NaCl): 3147.57 (N-H Vibration), 1541.82 (NH2+ str.), 1667.77 (C=N str.). 1 H-NMR (DMSO): δ,ppm. 3.2 (N-H), 2.5(-CH2), 2.1(CH3). 13C-NMR (DMSO): δ,ppm. 40.07(-CH2), 31.10 (-CH3). a a b Figure 2 structure of metal ligandL[1](a) and metal ligandL[2](b) where M = Ni, Cu and Zn b Figure 1 structure of ligand L[1](a) and ligand L[2](b) NiL[1]: FT-IR (Nujol, NaCl): 3169.79 (N-H 1 H-NMR Vibration), 1662.11 (C=N str.). (DMSO):δ,ppm. 3.2 (N-H), 2.6 (-CH2), 1.9 (-CH3). 13 C-NMR (DMSO): δ,ppm. 39.70 (-CH2) 24.59 (CH3). CuL[1]: FT-IR (Nujol, NaCl): 3169.25 (N-H Vibration), 1653.74 (C=N str.). 1H-NMR (DMSO): δ,ppm. 3.4 (N-H), 2.5 (-CH2). 13C-NMR (DMSO):δ,ppm. 40.09 (-CH2). ZnL[1]: FT-IR (Nujol, NaCl): 3212.35 (N-H Vibration), 1672.94 (C=N str.). 1H-NMR (DMSO): δ,ppm. 3.4 (N-H), 2.5 (-CH2), 2.1 (-CH3). 13C-NMR (DMSO): δ,ppm. 40.09 (-CH2) 31.12 (-CH3). NiL[2]: FT-IR (Nujol, NaCl): 3212.05 (N-H Vibration), 1669.86 (C=N str.). 1H-NMR (DMSO): δ,ppm. 3.3 (N-H), 2.5 (-CH2), 1.9 (-CH3). 13C-NMR (DMSO): δ,ppm. 40.07 (-CH2) 25.04 (-CH3). CuL[2]: FT-IR (Nujol, NaCl): 3124.85 (N-H Vibration), 1668.62 (C=N str.). 1H-NMR (DMSO): δ,ppm. 3.3 (N-H), 2.5 (-CH2). 13C-NMR (DMSO): δ,ppm. 40.01 (-CH2). ZnL[2]: FT-IR (Nujol, NaCl): 3149.44 (N-H Vibration), 1667.61 (C=N str.). 1H-NMR (DMSO): δ,ppm. 2.8 (N-H), 2.5 (-CH2), 2.0 (-CH3). 13C-NMR (DMSO): δ,ppm. 40.06 (-CH2) 31.11 (-CH3). 2.3 Synthesis acetylacetonate complexes Synthesis of Al(acac)3 The Al(acac)3 complex was synthesized by mixing acetylacetone(3.00 ml,0.03 mol.) and distilled water(40.00 ml) in a flask and followed by ammonia solution(8.00 ml,5.0M). Then aluminum sulphate solution(3.00 g,0.005 mol) in 30.00 ml of cold distilled water was added and shaked, the mixture was adjusted to pH ≈ 7. The mixture was filtered and washed with cold distilled water before dryingin vacuum. The product was further purified by recrystallization from cyclohexane. Finally, needle crystals were collected (69.10%). Synthesis of Mn(acac)3 The Mn(acac)3 complex was synthesized by mixing manganese(II)chloride tetrahydrate (2.60 g, 0.013mol.), sodium acetate (6.80 g, 0.05 mol. in 100 ml of distilled water) and acetylacetone(10.00 ml,0.100 mol.) Then potassium permanganate solution (0.52 g, 0.003 mol. in 5.00 ml of distilled water), was added and stirred. Then, sodium acetate (6.30 g,0.046 mol. in 25.00 ml of distilled water) was added, while stirring and heating the mixtureto 70°C for 30 minutes and then cool to room temperature. The mixture was filtered and washed with cold distilled water and dried under vacuum. The brown black needle products were obtained from the crystallization with hot cyclohexane and diethyl ether (68.20%). Synthesis of Fe(acac)3 The Fe(acac)3 complex was synthesized by mixing iron(III)chloride hexahydrate (3.30 g ,0.012 mol. in 25.00 ml of distilled water) and acetyl acetone (3.80 ml,0.038 mol. in 10.00 ml of ethanol). Then sodium acetate (5.10 g in 15.00 ml of distilled water) was added and stirred. The mixture was heated at 80°C for 15 minutes and then cooled to room temperature. The mixture was filtered and washed with cold distilled Pure and Applied Chemistry International Conference 2015 (PACCON2015) 184 water and dried under vacuum. Recrystallization of the product was performed in hot distilled water by adding methanol dropwise to obtain the product (75.30%). Synthesis of Co(acac)3 The Co(acac)3 complex was synthesized by refluxing cobalt(II)carbonate(2.50 g,0.021 mol.) with acetyl acetone(20.00 ml,0.200 mol.) The reaction was stirred 90°C, and 30.00 cm3 of a 10% hydrogen peroxide solution was added dropwise using a dropping pipette. Stirring should be maintained throughout the addition and further 15 minutes after the addition. The mixture was cooled in an ice bath for 30 minutes. The mixture was filtered and dried under vacuum. Dark green crystals were obtained. The products were recrystallized from hot toluene by adding diethyl ether to obtain dark green needles. (78.70%) Synthesis of Cu(acac)2 The Cu(acac)2 complex was synthesized by mixing copper(II)chloride dehydrate(4.00 g,0.025 mol. in 25.00 ml of distilled water) and acetyl acetone(5.00 ml,0.05 mol. in 10.00 ml methanol) in a flask. Then sodium acetate(6.80 g in 15.00 ml of distilled water) was added and the mixture was heated to 80°C on a hot plate for 15 minutes. The mixture was cooled to room temperature and then in an ice water bath. The mixture was filtered and washed with cold distilled water and dried under vacuum. The product was recrystallized from hot methanol as blue-gray needles. (73.50%) Al(acac)3: FT-IR (KBr disk,): 2925 (-CH3str.),1594.4 ((C=O str.) 1H-NMR (CDCl3): δ,ppm. 2.0 CH3), 5.5 (-CH). Mn(acac)3: FT-IR (KBr disk): 2922.72 (-CH3 str.),1588.06 (C=O str.) 1H-NMR (CDCl3): δ,ppm. 2.05 (-CH3), 5.5 (-CH). Fe(acac)3: FT-IR (KBr disk): 2920.30 (CH3 str.), 1570.81 (C=O str.) 1H-NMR (CDCl3): δ,ppm.2.2 (CH3), 5.3 (-CH). Cu(acac)3: FT-IR (KBr disk): 2922.22 (CH3 str.), 1577.81 (C=O str.). 1H-NMR (CDCl3): δ,ppm. 2.2 (CH3), 5.3 (-CH) a b Figure 3 structure of Cu(acac)2 (a) and M(acac)3(b) where M = Al, Mn, Fe and Co 2.4 Biological activity The antibacterial activities were evaluated against E. coli and S. aureus, by Disc diffusion method [12]. The compounds were dissolved in methanol (solvent control) to obtain concentration of 10 mg/L. Nutrient agar medium was prepared by using nutrient broth 4.00 g and agar 7.50 g in water. The disc of Whatmann No.1 filter paper having the diameter 5 mm was used. The compound solution (50μL, 10 mg/L) are applied on disc then placed over the media. The methanol was served as control solvent, while penicillin (10 mg/L) was selected for standard drug (inhibition zone of penicilin; E. coli = 1.1500 ± 0.0531 mm and S. aureus = 1.7820 ± 0.1940 mm). The samples were incubated for 24 h at 37 ± 2 °C. The inhibition zone was carefully measured in mm. 3. Results and Discussion 3.1 Elemental CHN analysis The ligands and complexes were characterized by elemental CHN analysis to confirm the success in the synthesized process. The elemental CHN analysis of all compounds is in agreement with theoretical value as show in Table 1. Table 1 Elemental CHN analysis data Compounds Ligand L[1] NiL[1] CuL[1] ZnL[1] Ligand L[2] NiL[2] CuL[2] ZnL[2] Al(acac)3 Mn(acac)3 Fe(acac)3 Co(acac)3 Cu(acac)2 Theoretical value (%) C H N 40.08 6.68 11.69 35.58 6.35 10.37 35.27 6.29 10.28 35.15 6.27 10.25 47.06 7.54 9.98 42.61 6.83 9.03 42.27 6.77 8.96 42.15 6.75 8.94 55.55 6.54 51.00 6.02 50.55 5.94 45.88 5.39 - Analyze value (%) C H N 38.51 7.09 12.31 35.32 5.95 10.22 34.56 6.41 10.18 34.44 6.39 10.55 46.59 7.69 9.78 43.46 6.89 9.12 41.43 6.91 8.87 41.73 6.96 8.76 55.55 6.53 51.01 5.99 50.57 5.94 45.88 5.39 - 3.2 UV-Vis spectroscopy Tetraaza macrocyclic complexes According to UV-Visible spectroscopy data of ligand L[1] and their complexes (NiL[1] and CuL[1]), when each metal ion (Ni2+ or Cu2+) was added in to ligand L[1], the soret band move to a longer wavelength. The energy band gap (HOMO and LUMO) of NiL[1] and CuL[1] from UV-Vis spectroscopy are less than ligand L[1]. However, in the complex ZnL[1], the soret band was moved to a shorter wavelength, compared with NiL[1] and CuL[1]. The zinc ion in ZnL[1] was Zn2+(d10).The higher energy may require to excite the ground state electron to excited state. The UV-Visible spectra of ligand L[2] and complexes (NiL[2], CuL[2], and ZnL[2]) are shown the same trends as that of ligand L[1] and complexes ML[1] the data are summarized in Table 2 The UV-vis spectra of complexes M(acac)3 (M=Mn3+,Fe3+and Co3+) and Cu(acac)2 were recorded in MeOH as a solvent. The spectra show a broad band, at 568, 429, 593 and 635 nm, for Mn(acac)3, Fe(acac)3, Co(acac)3 and Cu(acac)2 respectively. These bands correspond to the d-d transitions in each complexes, similarly to the results reported by Sertphon et.al [8]. Table 2 UV-Visible spectroscopy data Pure and Applied Chemistry International Conference 2015 (PACCON2015) 185 UV-Visible spectroscopy λmax (nm.) 243 243 436 436 505 511 243 241 Compounds Ligand L[1] Ligand L[2] NiL[1] NiL[2] CuL[1] CuL[2] ZnL[1] ZnL[2] Acetyl acetonate complexes Varying metal complexes from Fe(acac)3 to Mn(acac)3,Co(acac)3 and Cu(acac)2illustrated the red shift in the spectra of complexes. Similarly, replacing the solvent for these complexes [Fe(acac)3,Cu(acac)2] from MeOH to DMSO also shown small red shifts. This result might be because of weak attraction between the complexes and the solvent which atom known as solvatochromic effect [9]. In contrast, the red shift was not observed for Co(acac)3. Table3 UV-Visible spectroscopy data Compounds Mn(acac)3 Fe(acac)3 Co(acac)3 Cu(acac)2 UV-vis (solution) λmax MeOH DMSO 568 429 438 593 598 635 647 UV-vis (solid state)λmax 560 438 593 563 and S. aureus, respectively. The result of CuL[1] and Co(acac)3 showed greater inhibition than penicillin drug standard especially for E. coli. Therefore, the chelation between ligand and metal acetate make complex more powerful and potentially bacterial inhibiter agents E. coli andS. aureus. In complexes, the positively charge of metal ion was partially shared with the donor atom presented in ligands and may allow the π-electron delocalized over the whole complex, increasing the lipophilic character of complex. The complex may permeate through the lipid layer of the bacterial membranes and caused the bacteria die. Similar result was found in complex of PdC32H28N4Cl2 [10]. 4. Conclusions The tetraaza macrocycilc complexes and acetyl acetonate complexes have been synthesized and characterized by IR spectroscopy, 1H NMR, 13C NMR spectroscopy and CHN elemental analysis. The UVVisible spectroscopy showed that metal has been effected by on the energy gap of HOMO and LUMO of complexes. The antibacterial activity indicated the complexes and ligands were sensitive against both E. coli and S. aureus. The complexes CuL[1] and Co(acac)3 exhibited more inhibitory than other compounds for both of bacteria and greater inhibition capacity than penicillin drug. Acknowledgements 3.3 Biological activity In this study, the pure ligands, metal acetate andthe metal complexes were evaluated for their antibacterial activity against E. coli and S. aureus. The antibacterial screening data (Table 4) for all ligands, metal acetate and the metal complexes were found to be sensitive against both E. coli and S. aureus,inwhich each the inhibition zone was greater than control solvent (methanol). The complex CuL[1] exhibited the greatest inhibitory with clear zone = 1.350 ± 0.070 mm and 1.100 ± 0.072 mm for E. coli and S. aureus, respectively. Acetyl acetonate complexes Co(acac)3 exhibited the greatest inhibitory with clear zone = 1.825 ± 0.035 mm and 1.875 ± 0.247 mm for E. coli We are grateful to the Department of Chemistry, Faculty of Science and Technology, Thammasat University and Science Achievement Scholarship of Thailand (SAST), for financial and all experiments support. References [1] Kong, D. and Xie, Y., 2002, Inorganic ChimicaActa, 338, 142 – 148. [2] Keypour, H., Aezhangi, P., Rehpeyma, N., Rezaeivala, M., Elerman, Y. and Khavasi, H. R., 2011, Inorganic ChimicaActa, 367, 9 – 14. Table 4 Antibacterial screening data for ligands and their complexes Complex Ligand L[1] Ligand L[2] NiL[1] NiL[2] CuL[1] CuL[2] ZnL[1] Al(acac)3 Mn(acac)3 Fe(acac)3 Co(acac)3 Cu(acac)2 Escherichia coli Inhibition zone (mm) 1.100±0.070 0.980±0.040 1.230±0.113 1.050±0.075 1.352±0.072 0.943±0.000 0.941 1.209±0.496 1.675 ±0.106 1.750±0.212 1.650±0.071 1.825±0.035 1.400±0.212 Control Staphylococcus aureus Inhibition zone (mm) 0.812±0.002 0.880±0.045 0.889±0.040 1.084±0.047 1.100±0.078 1.039±0.116 0.810 0.989±0.040 1.650±0.000 1.575±0.106 2.025±0.200 1.875±0.247 1.150±0.000 Control Pure and Applied Chemistry International Conference 2015 (PACCON2015) 186 [3] Chen, L. and Cotton, F. A., 1998, Journal of Molecular Structure, 470, 161 – 166. [4] El-Boraey, H. A., 2012, SpectrochemicalActa Part A: Molecular and Biomolecular spectroscopy, 97, 255-262. [5] Kong, D., Meny, L., Ding, J., Xie, Y. and Huang, X., 2000, Polyhedron 19, 217 – 223. [6] Tyagi, M. and Chabdra, S., 2014, Journal of Saudi Chemical Society, 18, 53-58. [7] Masih, I. and Fahmi, N., 2011, SpectrochemicaActa Part A, 79, 940 – 947. [8] Patrique, N., Nora, V. N., Elisabete, C.B.A.A., Armando, J.L.P. and Isabel, C., 2014, Journal of Molecular Structure, 1060, 142–149. [9] Yogesh, S.W. and Bhalchandra, M.B., 2012, Tetrahedron Letters, 53, 6500-6503 [10] Chandra, S., Tyagi, M. and Agrawal, S., 2011, Journal of Saudi Chemical Society, 15, 49 – 54 Pure and Applied Chemistry International Conference 2015 (PACCON2015) 187 ONE POT SYNTHESIS OF FREE BASE MESO-TETRA (SUBSTITUTED PHENYL) PORPHYRINS Jantima Sukjan, Supakorn Boonyuen*, Wootthiphan Jantayot Department of Chemistry, Faculty of Science and Technology, Thammasat University, Pathumthani, 12120, Thailand * E-mail: [email protected] Abstract: In this work, a series of meso-tetra (substituted phenyl) porphyrins was synthesized and characterized. A modified Adler method was used for the synthesis of symmetrical porphyrins by condensation reaction between pyrrole and different substituted benzaldehydes in propionic acid. The synthesized porphyrins were characterized by using proton nuclear magnetic resonance spectroscopy, ultraviolet–visible spectroscopy, fluorescence spectroscopy and mass spectrometry. In this study, the trend of free base porphyrins when the aldehyde precursors were different in the ability to provide electron density to the π system was studied. The aldehyde precursors were benzaldehyde, 4hydroxybenzaldehyde, 4-methoxybenzaldehyde and 4carboxybenzaldehyde. The product yield of TPP, TOMPP, TMPP, THPP and TCPP are 36.0%, 25.7%, 36.2%, 12.3 and 36.2%, respectively. The spectroscopic information of synthesized compounds confirmed the expected structures. The results showed that one pot synthesis reaction was successful. 1. Introduction 3 2 1 20 Methine br idge 4 5 N H 19 6 7 18 N N 8 17 16 15 9 H N Porphyrins are found in many natural systems, where they play an essential role as photoactive, redox, guest-binding, and catalytic entities. They are of immense biological importance and have fascinating physical, chemical, and spectroscopic properties. Because of their special properties, porphyrins have wide applications in many fields such as biomimetic catalysis, electro catalysis, biological sensors, solar energy conversion, and so on. They are also important in biomimetic models, and in fact they are widely used as models to study oxygen transport4. Photophysical properties of porphyrin derivatives have been the target of a huge amount of investigations during the past few decades, motivated by the possibilities of their use in a large variety of applications including light harvesting systems5, photodynamic therapy6, chemical sensors7-8 and others. The aims of this research mainly focus on two different topics: a) the synthesis of symmetrical porphyrin and b) characterization and study the chemical properties of synthesized porphyrins. The first objective of this work is to synthesize symmetrical phenylporphyrins containing hydroxyl or alkoxy or alkyl or carboxyl functional group on the para position of the phenyl rings. The second objective is to characterize all synthesized porphyrins and to study their properties such as electronic absorption and electronic emission for further applications. 10 14 11 Meso position 13 2. Materials and Methods 12 Figure1. The structure of porphyrins Porphyrins are one of the important chemical parts essential for several life processes in nature. Moreover, porphyrin is the name given to a family of intensely colored molecules all sharing a macrocycle of twenty carbon atoms and four nitrogen atoms. The porphyrins are aromatic molecules where four pyrrole rings forming a square, are connected by unsaturated methine bridges to complete a macrocycle (Figure 1)1. They are aromatic macrocycles containing a total of 22 conjugated π electrons, 18 of which are incorporated into the delocalized pathway in agreement with Huckel’s [4n + 2] rule for aromaticity (n = 4). The porphyrin macrocycles are quite flexible and easy for being π-delocalized system by introducing substituents at β- or meso-positions, adding the central metal or extending the macrocycle.1-3 2.1 Reagents The reagents were purchased and used without further purification. Liquid reactants and solvents were distilled prior to use. The distilled water was used. Flash column chromatography was performed on Silica gel 60. 2.2 Materials Electronic absorption spectra were carried out on a SHIMADSU UV-Vis spectrophotometer using a pair of quartz cells of 10 mm path length at room temperature. Emission spectra of porphyrins were measured by a Jasco FP-6200 spectrofluorometer at room temperature. Nuclear magnetic resonance spectra were recorded at 400 MHz for 1H NMR using a BRUKER-NMR 400MHz spectrometer. Infrared spectroscopy spectra (4000-600 cm-1) were performed using a spectrum GX FT-IR spectrometer (Perkin Pure and Applied Chemistry International Conference 2015 (PACCON2015) 188 Elmer). Mass spectra of the porphyrins were recorded on a Thermo Finnigan mass spectrometer. 2.3 Methods Scheme1. The synthesis of free base porphyrins The free-based porphyrins that containing hydroxyl or alkoxy or alkyl or carboxyl functional group on the para position of the phenyl rings were synthesized by a condensation reaction between pyrrole and aldehyde in propionic acid according to the development of AdlerLongo method (scheme1)9. Pyrrole (1.0 ml, 14.3 mmol) was taken in a round bottomed flask, to which propionic acid (100 ml) was added. To the above stirred solution, aldehyde (benzaldehyde: 1.5 ml, 14.7 mmol, p-tolubenzaldehyde: 1.5 ml, 12.7 mmol, panisaldehyde: 1.5 ml, 12.4 mmol, 4hydroxybenzaldehyde: 1.75 g, 14.3 mmol, or 4carboxybenzaldehyde: 2.15, 14.3 mmol) was added dropwise. The reaction mixture was refluxed and stirred for 60 minutes at 90˚C. Reaction was monitored by TLC (hexane: dichloromethane) when reaction completed. Then the dark brown mixture after cooling was filtered that the solvent was remove under reduce pressure. The deep-purple crystals are the resulting residues. Moreover, the compound was purified by using silica gel column chromatography and recrystallization. In column chromatography part, the wet method was used to prepare a column. The free base porphyrin was prepared of within the small of silica gel powder which is a stationary phase. The sample to be purified was dissolved in a small amount of appropriate solvent, and then loaded onto the top of column. The eluting solvent changed to a more polarity solvent during the elution process and the composition of each fraction is analysed by TLC-silica. After purification, the UV-Vis absorption spectra of these compounds were studied by recording between 200 and 800 nm, the fluorescence spectra were measured in range 530-700 nm. 1H NMR, the infrared spectroscopy and mass spectrometry were measured for study chemical properties to confirm the structure. 5,10,15,20-Tetraphenylporphyrin (TPP): FT-IR (Nujol, NaCl): 3435 (N-H str., porphyrin), 3054, 2987 (C-H str., phenyl), 1605, 1158 (C=C str., phenyl), 1558 (C-C str., porphyrin), 1269 (C-N str., porphyrin), 1018 (N-H bend, porphyrin), 896 (C-H bend, porphyrin) cm-1. 1H NMR (400 MHz, CDCl3): δ 8.85 (Pyrrole, β-H), 8.21 (Phenyl, o-H), 7.73 (Phenyl, m- H), 7.75 (Phenyl, p-H), -2.71 (Pyrrole, N-H). Mass spectrum (m/z): 615.3 (cal., 615.78). 5,10,15,20-Tetrakis(4-methylphenyl)porphyrin (TMPP): FT-IR (Nujol, NaCl): 3436 (N-H str., porphyrin), 3054, 2986 (C-H str., phenyl), 1606, 1158 (C=C str., phenyl), 1558 (C-C str., porphyrin), 1263 (C-N str., porphyrin), 1018 (N-H bend, porphyrin), 896 (C-H bend, porphyrin) cm-1. 1H-NMR (400 MHz, CDCl3): δ 8.85 (Pyrrole, β-H), 8.18 (Phenyl, o-H), 7.56 (Phenyl, m-H), 2.70 (-CH3), -2.77 (Pyrrole, N-H). Mass spectrum (m/z): 671.4 (cal., 671.84). 5,10,15,20-Tetrakis(4-methoxylphenyl)porphyrin (TOMPP): FT-IR (Nujol, NaCl): 3435 (N-H str., porphyrin), 3053, 2987 (C-H str., phenyl), 1606, 1153 (C=C str., phenyl), 1553 (C-C str., porphyrin), 1265 (C-N str., porphyrin), 1017 (N-H bend, porphyrin), 895 (C-H bend, porphyrin) cm-1. 1H-NMR (400 MHz, CDCl3): δ 8.88 (Pyrrole, β-H), 8.13 (Phenyl,o-H), 7.35 (Phenyl, m-H), 4.22 (-OCH3), -2.82 (Pyrrole, N-H). Mass spectrometry (m/z): 735.3 (cal., 735.84). 5,10,15,20-Tetrakis(4-hydroxyphenyl)porphyrin (THPP): FT-IR (Nujol, NaCl): ~3200-3400 broad band (O-H str., phenyl), 3314 (N-H str., porphyrin), 2937, 2869 (C-H str., phenyl), 1604, 1170 (C=C str., phenyl), 1479 (C-C str., porphyrin), 1232 (C-N str., porphyrin), 967 (N-H bend, porphyrin), 802 (C-H bend, porphyrin) cm-1. 1H-NMR (400 MHz, CDCl3): δ 9.80 (Phenyl, -OH), 8.90 (Pyrrole, β-H), 8.15 (Phenyl,o-H), 7.30 (Phenyl, m-H), -2.82 (Pyrrole, NH). Mass spectrometry (m/z): 678.2 (cal., 677.74). 5,10,15,20-Tetrakis(4-carboxyphenyl)porphyrin (TCMPP): FT-IR (Nujol, NaCl): 3407 (N-H str., porphyrin), 2924, 2862 (C-H str., phenyl), 1686 (C=O, carboxylic acid), 1604 (C=C str., phenyl), 1386 (C-N str., porphyrin), 962 (N-H bend, porphyrin), 798 (C-H bend, porphyrin) cm-1. 1H-NMR (400 MHz, CDCl3): δ 8.85 (Pyrrole, β-H), 8.32 (Phenyl,o-H), 8.25 (Phenyl, m-H), -2.82 (Pyrrole, N-H). Mass spectrometry (m/z): 790.1 (cal., 789.77). R R N H N R = H; TPP R = CH3; TMPP R = OCH3; TOMPP R = OH; THPP R = CO2H; TCPP N H N R R Figure2. The structure of free base porphyrins 3. Results and Discussion The free base porphyrins, including TPP, TMPP, TOMPP, THPP and TCPP were prepared using a modification of Adler-Longo method, i.e. by the heating of pyrrole in propionic acid solvent followed by addition of the same amount of aldehyde, further Pure and Applied Chemistry International Conference 2015 (PACCON2015) 189 heated for one hour, resulting in the dark solution with deep purple microcrystals. The absorption spectra of all synthesized was shown in Figure 3. They exhibited an extreme intense band as a Soret band (S-band ranged from 405.0 – 413.5 nm). At lower energy, the spectra contain a set of weaker four absorption bands (Q-band as shown in Table 1). The intensity and color of porphyrins were derived from the highly conjugated π-electron systems and the most attraction feature of porphyrins was their characteristic UV-visible spectra that consist of two distinct regions, in the near ultraviolet (Soret band) and in the visible regions (Q bands). The absorption bands in porphyrin systems arise from transitions between two HOMOs and two LUMOs. The fluorescence spectra of free base porphyrins show only one electron transition occurs at 649-656 nm, when excited at 513-518 nm. TMPP, TOMPP and THPP were little shift to a longer wavelength when comparing with TPP. It can conclude that the shifting of emission spectra was depended on the ability to donate electron to the benzene ring of the substituents. The structure of each complex was confirmed by FT-IR, 1H NMR, and mass spectrometry. Structural studies by IR Spectroscopy found that the spectra of each compound were quite similar. Each position has shifted slightly because of the influence of substituents. This result was expected as the ring core part of porphyrins was the same. From mass spectrometry, all free base porphyrins were consistent with the expected structures. 4. Conclusions Tetraphenylporphyrin with different in mesosubstituted position were successfully synthesized. The colors of all synthesized compounds are in the purple with micro crystals. The structure of each free base porphyrins were confirmed by FT-IR, 1H NMR, and mass spectrometer, which in agreement with the expected values. The absorption spectroscopy showed the intense S-band (405.0 – 413.5 nm) and weak Qbands, ranging from 513 to 650.5 nm. The fluorescence spectra (excitation at 513-518 nm) showed emission bands at 649 - 656 nm. The financial and all experiments equipment were Figure3. UV-Vis absorption spectra of free base porphyrins supported by the Thailand Research Fund (TRF), Department of Chemistry, Faculty of Science and Technology, Thammasat University and the Navamin project of National Research Council of Thailand. References [1] Gouterman, M., 1961, J. Mol. Spectrosc., 6, 138–163. [2] Gouterman, M., Wagnire, G.H. and Snyder, L.C., 1963, J. Mol. Spectrosc., 11, 108–127. [3] Kalyanasundaram, K., 1992, Academic Press, San Diego, 1992. [4] Pavinatto, F.J., Gameiro Jr, A.F., Hidalgo, A.A., Dinelli, L.R., Romualdo, L.L., Batista, A.A., Barbosa Neto, N.M., Ferreira, M. and Oliveira Jr., O.N., 2008, Appl. Surf. Sci. 254, 5946–5952. [5] Gust, D., Moore, T.A. and Moore, A.L., 2001, Acc. Chem. Res., 34, 40–48. [6]Ochsner, M., 1997, J. Photochem. Photobiol. B, 39, 1–18. [7] Chou, J.H., Kosal, M.E., Nalwa, H.S., Rakow, N.A. and Suslick, K.S., 2000, Applications of porphyrins and metalloporphyrins to materials chemistry, in: K. Kadish, K. Smith, R. Guillard (Eds.), The Porphyrin Handbook, Academic Press, New York. [8] Pavinatto, F.J., Gameiro Jr., A.F., Hidalgo, A.A., Dinelli, L.R., Romualdo, L.L., Batista, A.A., Barbosa Neto, N.M., Ferreira, M. and Oliveira Jr., O.N., 2008, Appl. Surf. Sci., 254, 5946–5952. [9] Kilian, K. and Pyrzyńska, K., 2003, Talanta., 60(4), 669678. Acknowledgements Table 1: Percentage yield, mass spectrometric, UV-Visible spectroscopy data and fluorescence spectroscopy data of meso-substituted porphyrins Compounds (Molecular Mass) Yield (%) Major product ion(m/z) TPP (614.78) TMPP (670.84) TOMPP (734.84) THPP (678.74) TCPP (790.77) 36.0 36.2 25.7 12.3 36.2 615.3 671.4 735.3 678.2 790.1 UV-Vis absorption (nm) S-band (ε x 103 ) 405.0 (28.5) 408.0 (29.8) 413.5 (22.0) 407.0 (25.7) 405.0 (28.6) Q-band 1 514.0 516.0 518.0 517.0 513.0 2 549.0 551.5 555.5 554.0 547.0 3 590.0 591.5 594.0 592.0 589.0 4 646.0 648.0 650.5 650.0 644.0 Pure and Applied Chemistry International Conference 2015 (PACCON2015) Fluorescence (nm) Excita- Emistion Sion 514.0 649.0 516.0 652.0 518.0 655.0 517.0 656.0 513.0 648.0 190 SYNTHESIS AND CHARACTERIZATION OF LONG CHAINED PORPHYRIN DERIVATIVES AND COBALT COMPLEXES Wootthiphan Jantayot, Supakorn Boonyuen*, Jantima Sukjan, Kamolnate Jansaeng Department of Chemistry, Faculty of Science and Technology, Thammasat University, Pathumthani 12120, Thailand *E-mail: [email protected] Abstract: In the present work, the synthesis and properties of long chained porphyrin and their cobalt complexes were examined. The compounds were synthesized by Adler-Longo method, refluxing aldehyde and pyrrole in propionic acid. The modified porphyrins are tetrakis(4-methoxyphenyl)porphyrin (TOMPP), tetrakis(4-butyloxyphenyl)porphyrin (TOBPP), tetrakis (4-octyloxyphenyl)porphyrin (TOOPP) and tetrakis(4decyloxyphenyl)porphyrin (TODPP). The products were obtained in 26%, 5%, 13 and 14% yields, respectively. Further refluxing the ligands with cobalt acetate in DMF gave CoTOMPP, CoTOBPP, CoTOOPP and CoTODPP, respectively with yields ranging from 75 to 92% yields. All ligands and complexes were characterized by 1HNMR, MS, IR, UV-Vis and fluorescence spectroscopy, and the results were in agreement with the expected structures. 1. Introduction Porphyrins are planar aromatic macrocycles and biochemically important in nature. They are ubiquitous classes of compounds with many important biological representatives including heme, chlorophyll, coenzyme F430 and several others [1]. The nature of bonding between a central metal and the porphyrin ligand is found to be originating essentially from the following two types of primary interactions: σ-coordination of nitrogen lone pairs directed towards the central metal atoms and πinteractions of metal pπ or dπ orbitals with nitrogenbased π orbitals [2]. Ability to exhibit variable oxidation states of metals in their metalloporphyrins are another important feature in this class of compounds. Porphyrins and their metal complexes have received much attention. This has been mainly due to the use of these compounds in catalysis, as materials with novel electrical properties and as biomimetic model systems of primary processes of natural photosynthesis [3-5]. They can be used as photosensitizing drugs in photodynamic therapy (PDT). An extra stabilization of the porphyrin occurs by complexation with transition metal ions and which has been explained by the macrocyclic effect [6]. Porphyrins and their derivatives have well-known technological applications. Concerning the field in which the stability is one of the essential parameters to be considered, aspects such as the use as dyes in solar cells to improve efficiency [7]. Porphyrins can be used as biodiesel fluorescent markers [8-9]. In the present work, the application of Adler Longo synthesis method was selected to apply for the porphyrin derivatives due to the most convenient process. Porphyrin derivatives and cobalt porphyrins were prepared and purified. Then, their properties were characterized by IR spectroscopy, 1H NMR spectroscopy and mass spectrometry (MS).To study the properties of porphyrin derivatives and cobalt porphyrins, the absorption spectra and emission spectra were analyzed by using UV-Vis spectrophotometry and spectrofluorometer in dichloromethane. 2. Methodology 2.1Apparatus Nuclear magnetic resonance spectra were recorded at 400MHz on a Bruker (FT-NMR advance 400 MHz) spectrometer. FT-IR (4000-400cm-1) spectra were recorded on Perkin Elmer infrared spectrophotometer (spectrum GX). Mass spectra were obtained from Thermo Finnigan mass spectrometer (LCQ Advantage). UV-Vis absorption and fluorescence measurements were carried out on a Shimadzu UV-spectrometer (UV-1700) and a Jasco spectrofluorometer (FP-6200), respectively. 2.2 Method 2.2.1 Synthesis of aldehyde H O O + n K2CO3 n Br H DMF, 353 K 2 hr. OH 4-Hydroxybenzaldehyde Alkyl bromide O Alkyloxybenzaldehyde n=3, 1-Bromobutane n=7, 1-Bromooctane n=9, 1-Bromodecane Figure 1.Synthesis of butyloxybenzaldehyde, octyloxybenzaldehyde and decyloxybenzaldehyde. A mixture of 4-hydroxybenzaldehyde (17.5 mmol) and K2CO3 (18 mmol) was stirred in DMF. Various alkyl bromide (18 mmol) was added dropwise and the mixture was heated at 353 K for 2 hour. After cooling, the salts were filtered. DMF was evaporated to dryness, and the reaction mixture was re-dissolved in CH2Cl2 and washed with distilled water. Magnesium sulfate anhydrous was used for drying. Alkyloxybenzaldehyde as yellow oil was afforded by filtration Pure and Applied Chemistry International Conference 2015 (PACCON2015) 191 Porphyrin was used to reflux (0.04mmol) with and evaporation. The reaction products were used Table 2: 1H NMR spectroscopic data and FT-IR data for porphyrins long chain and cobalt porphyrins. without any further purification [10]. cobalt acetate [(Co(II)(CH3COO)2)] (0.40mmol) in DMF for 4 hours. The reactions mixture was diluted with water and extracted with dichloromethane, and the solvent was removed by evaporator. Cobalt complexes were recrystallized. The title compounds were isolated by column chromatography as purple solid [13]. 2.2.2 Synthesis of porphyrin with long chain R R O Propionic acid H Reflux , 383 K 4R 4 N H N N H N H N 3. Results and Discussion R R R= OCH3 R= O(CH2)3CH3 R= O(CH2)7CH3 R= O(CH2)9CH3 The porphyrin derivatives, including TOMPP, TOBPP, TOOPP and TODPP were synthesized by a modification Adler-Longo method. Porphyrins were obtained from 5 to 26% yields. Adding cobalt ion into the central position of ligands (CoTOMPP, CoTOBPP, CoTOOPP, CoTODPP) by refluxing in DMF gave the yields of the products ranging from 75 to 92% yields. The characterization data of purified porphyrin derivatives and cobalt complexes are shown in Table 1. The mass spectra of porphyrins long chain and cobalt porphyrins could also confirm that the expected structures as shown in Table 1. Figure 2.Synthesis of TOMPP, TOBPP, TOOPP and TODPP. Porphyrins were synthesized by following the development of Adler-Longo method [11-12]. A round-bottomed flask equipped with a magnetic stirring bar and a reflux condenser was charged with various alkyloxybenzaldehyde (14 mmol), and propionic acid and stirred for 15 min at 383 K. Pyrrole (14 mmol) was added slowly, and the mixture was refluxed for 2 hour. After refluxing, the reaction mixture was cooled to room temperature and added 40 mL ethanol, kept in ice bath overnight. The purple crystals were filtered, washed, and dried by vacuum filtration with cold ethanol to remove traces of propionic acid. The crude products were purified by column chromatography to yield a purple crystal product. Table 1: Characteristic data for porphyrins long chain and cobalt porphyrins. Compounds Empirical formula Yield (%) Formula weight Msm/z (ESI) TOMPP TOBPP TOOPP TODPP CoTOMPP CoTOBPP CoTOOPP CoTODPP C48H38N4O4 C60H62N4O4 C76H92N4O4 C84H108N4O4 CoC48H36N4O4 CoC60H60N4O4 CoC76H90N4O4 CoC84H106N4O4 26 5 13 14 75 92 81 88 734.84 903.16 1125.57 1237.78 791.76 960.08 1182.49 1294.70 735.32 902.19 1126.41 1238.46 793.01 959.95 1184.33 1294.29 2.2.3 Synthesis of cobalt (II) porphyrins R R N N H N H N N + Co(CH3COO)2 DMF Reflux R R R R N Co N N Porphyrins long chain were dissolved in chloroform-d (CDCl3) and the 1H NMR data for the corresponding compounds are shown in Table 2. Cobalt complexes were unable to identify by 1H NMR spectroscopy due to a paramagnetic character. The shielding effect of the proton signals of -NH groups in porphyrin ring was observed at very high fields. R R R= OH R= OCH3 R= O(CH2)3CH3 R= O(CH2)7CH3 R= O(CH2)9CH3 Figure 3.Synthesis of CoTOMPP, CoTOBPP, CoTOOPP and CoTODPP. 1 Porphyrins Pyrrole β-H TOMPP 8.9 TOBPP TOOPP TODPP CoTOMPP CoTOBPP CoTOOPP CoTODPP Phenyl , o-H Phenyl, m-H IR (cm-1) H NMR (ppm) O CH3 O CH2 OCH2 CH2 CH2 CH3 CH2 CH2 CH3 N-H str. C-H str. C=C str. 2928, 1606, 2832 1509 2929, 1605, 8.9 8.1 7.3 4.3 2.17 1.6 1.26 3318 2868 1507 2926, 1606, 8.9 8.1 7.3 4.3 2.0 1.65 1.55 0.95 3316 2850 1508 2923, 1606, 8.9 8.1 7.3 4.2 2.0 1.65 1.55 0.95 3310 2852 1509 2929, 1602, 2829 1504 2935, 1605, 2857 1507 Unable to identify due to paramagnetic character in 1H NMR data 2924, 1607, 2845 1509 2924, 1606, Pure and Applied Chemistry International Conference 2015 (PACCON2015) 2853 1505 8.1 7.3 4.2 - - - - - 3317 C-N str. C-O str. N-H bend C-H bend 1247 1175 965 802 1244 1173 965 800 1242 1174 965 803 1243 1175 967 804 1248 1174 - 800 1245 1174 - 794 1244 1174 - 797 1241 1173 - 795 192 Table 3: The absorption and emission data of porphyrins long chain and cobalt complexes in dichloromethane Dichloromethane Porphyrins TOMPP TOBPP TOOPP TODPP CoTOMPP CoTOBPP CoTOOPP CoTODPP Soret band (nm), Ɛ (103M-1cm-1) 422, 115.4 422, 112.5 412, 120.4 415, 122.5 407, 133.3 414, 130.4 407, 131.7 415, 125.4 Q1 517, 24.0 519, 21.4 519, 20.0 519, 16.7 530, 17.3 531, 17.8 531, 16.8 531, 12.9 Q band (nm), Ɛ (103M-1cm-1) Q2 Q3 556, 16.6 556, 16.2 556, 14.9 556, 12.5 611, 1.5 613, 4.6 613, 3.1 614, 2.7 594, 7.6 595, 7.3 595, 6.7 595, 5.5 - Q4 651, 10.2 651, 13.6 651, 10.1 651, 9.2 - Excitation wavelength (nm) 530 530 530 530 540 540 540 540 Emission wavelength (nm) 655 655 655 655 - *All solution were prepared in the concentration of 3X10-5mol/L, (n =3, %RSD ≤ 1.6). (-2.71ppm). The results are in agreement with the previous reported by A.Zabardasti [14]. FT-IR spectra of porphyrins long chain and cobalt porphyrins were recorded using KBr pellets, ranging from 4000-400 cm-1. The IR data are showed in Table 1. The most significant difference of free porphyrins and cobalt porphyrins were N-H stretching and N-H bending in the porphyrin ring. The signal at around 3310cm-1 (N-H stretching) and 965 cm-1 (N-H bending) were disappeared because nitrogen atom in cobalt porphyrin was bound to the metal ion. (a.) (b.) Figure 4.UV-Vis spectra of porphyrin derivatives (a) and cobalt complexes(b) in CH2Cl2 The intensity absorption and color of porphyrins were derived from the highly conjugated π-electron systems. The most attraction feature of porphyrins was their characteristic UV-Visible spectra that consist of two distinct regions: the near ultraviolet called the Soret band (380-450 nm) and the visible region called Q-band (500-700 nm). The absorption spectra of porphyrin derivatives showed significant characteristics of one soret band and four Q-bands, as shown in Figure 4. The electronic spectra of the TOMPP and derivatives in dichloromethane were investigated and the λ max values were given in Table 3. In metalloporphyrin, the proton on NH group of porphyrin was deprotonated and then the nitrogen atom binds with metal ion to give the metal-porphyrin. The cobalt ions acting as Lewis acids interact with the lone-pair electrons of porphyrin ligand. These observed intense absorption bands were due to absorption(s) in the porphyrin ligands, involving the excitation of electrons from π to π* prophyrin ring orbital [15], as shown in Figure 4. The absorption band of cobalt complexes display two Q-bands. The results are shown in Table 3. Figure 5. Excitation spectrum and emission spectrum of TOMPP in CH2Cl2 The term of band gap refers to the energy difference between the top of the valence band to the bottom of the conduction band, electrons are able to jump from one band to another. The process requires a specific minimum amount of energy for the transition, the band gap energy [16]. The estimated energy gap determined from an intersection of UV-Vis absorption (Q4-band) and fluorescence emission spectrum was calculated as described previously [17]. The energy gap of TOBPP was 1.90 eV. The absorption and emission spectra of TOBPP are showed in Figure 5. Fluorescence spectroscopy of porphyrin derivatives was characterized in dichloromethane and the results are provided in Table 3. The published information, exhibited the enlargement of the π-conjugation yielding the emission characteristics at the emission from 655 nm when excited at 530 nm. However, the current work selects the first Q-band as the excitation wavelength, the spectra also showed strong fluorescence intensity. The results indicated that these free base porphyrins can potentially be used in fluorescent sensors and fuel marker applications. 4. Conclusions The novel porphyrins with long chain and cobalt porphyrins have been synthesized and their identities were confirmed by mass spectrometry (MS), 1H NMR, FT-IR spectra, UV-Vis and fluorescence spectroscopy.The free porphyrin ligand at optimal condition (refluxing in propionic acid) was obtained from 5 to 26% yields. Reactions of ligands with metal ions gave CoTOMPP, CoTOBPP, CoTOOPP and CoTODPP in 75%, 92%, 81%and 88% yields, respectively. The pure ligand gave the lower product yield than metal complexes. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 193 The UV-Vis absorption spectra for porphyrins long chain exhibited a single S-band with four Q-bands, which the cobalt complexes showed a single S-band couple with only two Q-band. Exciting the synthesized long chain porphyrin, the product showed the fluorescence spectra at 655 nm. All porphyrin derivatives can potentially be used as fluorescence probe in sensors and marker applications. [7] [8] [9] [10] Acknowledgements The financial and all experiments equipment were supported by the Thailand Research Fund (TRF), Department of Chemistry, Faculty of Science and Technology, Thammasat University and the Navamin project of National Research Council of Thailand.Theauthorsgratefullyacknowledgethefinancia lsupportprovidedbyThammasatUniversityResearchFun dundertheTUresearchScholar, Contractno27/2557 [11] [12] [13] References [1] [2] [3] [4] [5] [6] Bertini, I. and Gray, H.B., 2007, Biological Inorganic Chemistry (University Science Books, Sausalito) Collman, J.P., Hallbert, T.R. and Suslick, K.S., 1980, Metal ion activation of dioxygen,In Metal Ions in Biology, 2. Meunier, 1992, Metalloporphyrins as versatile catalysts for oxidation reactions and oxidative DNA cleavage, Chem., 92, 1411. Wagner, R., and Lindsey, 1994,A molecular photonic wire,J. Am. Chem., 116, 9759. Kurreck, H., and Huber, M., 1995, Model reactions for photosynthesis-photoinduced charge and energy transfer between covalently linked porphyrin and quinine units, Angew. Chem. Int. Ed. Engl., 34, 849. Brumbach, M.T. et al., 2009, Metalloporphyrin assemblies on pyridine-functionalized titanium dioxide, Langmuir, 25, 10685–10690. [14] [15] [16] [17] Shargh, H. et al., 2004, Novel synthesis of mesotetraarylporphyrins using CF3SO2Cl under aerobic oxidation, Tetrahedron, 60, 1863-1868. Siriorn, P., Amorn, P., and Patchanita, T., 2009, A porphyrin derivative from cardanol as a diesel fluorescent marker, Dyes and Pigments, 82, 26-30. Ana, C. B. F., Kleber, T. O., and Osvaldo, A. S., 2011, Newporphyrins tailored as biodiesel fluorescent markers, Dyes and Pigments, 91, 383-388. Ioannis, D. Kostas, et al., 2007, The first use of porphyrins as catalysts in cross-coupling reactions: a water-soluble palladium complex with a porphyrin ligand as an efficient catalyst precursor for the SuzukiMiyaura reaction in aqueous media under aerobic conditions, Tetrahedron Letters, 48, 6688-6691. Hua, C. et al., 2009, Crystal structure of meso-tetrakis [4-(pentyloxy)phenyl] porphyrin, J ChemCrystallogr., 39, 51-54. Hong, B. Zhao et al., 2013, meso-Tetrakis[4(heptyloxy)phenyl]porphyrin, Acta.Cryst., C69, 651653. Ekaterina, S. Z., Natalya, A. B., and Andrey, F. M., 2012, Covalent-bound conjugates of fullerene C60 and metal complexes of porphyrins with long-chain substituents, Mendeleev Commun., 22, 257-259. Zabardasti, A., 2012, Molecular interactions of some free base porphyrins with σ- and π-acceptor molecules, molecular interactions, Prof. Aurelia Meghea (Ed.), ISBN: 978-953-51-0079-9. Bandgar, B., Gujarathi, P., 2008, Synthesis and characterization of new meso-substituted unsymmetrical metalloporphyrins, J. Chem. Sci. 120, 259-266. Simple method of measuring the band gap energy value of TiO2 in the powder form using a UV/Vis/NIR spectrometer, Available form: http://www.perkinelmer/Content/applicationnotes/app_ uvvisnirmeasurebandgapenergyvalue.pdf Gamboa, M. and Campos, M., 2010, Study of the stability of 5,10,15,20-tetraphenylporphine (TPP) and metalloporphyrinsNiTPP, CoTPP, CuTPP, and ZnTPP by differential scanning calorimetry and thermogravimetry, The Journal of Chemical Thermodynamics, 42(5), 666-674. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 194 SYNTHESES OF MAGNETIC NANOCOMPOSITE SIZE SERIES Wishulada Injumpa, Numpon Insin* Materials and Catalysis Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Thailand, Bangkok * E-mail for Corresponding Author; E-mail:[email protected], Tel. +66 22187581, Fax. +66 22187598 Abstract: Different sizes of composites of magnetic nanoparticles (MNPs) with narrow size distribution were synthesized by two pathways. In the first method, magnetites (Fe3O4) MNPs were synthesized using thermal decomposition of iron oleate complex at above 290oC. The resulting Fe3O4MNPs were then coated by silica via a reverse microemulsion method, producing the coreshell nanostructures of Fe3O4 MNP@SiO2. For the second pathway, silica nanoparticles (SiO2 NPs) with diameters of 50–100 nm were prepared using a reverse microemulsion method. Combining the Fe3O4MNP solution with SiO2 NPs afforded silica-Fe3O4 (SiO2-Fe3O4) magnetic nanocomposites (MNCPs). Sizes of MNCPs can becontrolled within narrow size distribution of 20 to 150 nm in diameter. Small sizes MNCPs (20-40 nm)can be controlled by adjusting the ratio of TEOS:MNPsfrom first pathways. The second method gave lager sizes ofMNCPs with ~120 nm in diameter. 1. Introduction Nanomaterials are well known for their applications in biological field such as drug delivery system (Doxorubicin drug for tumour cells) [1] and labelled-cell system (Magnetic resonance imaging or MRI) [2]. One of the most important factors to be considered for both systems is the size of nanomaterials because different sizes of nanomaterials will affect the cellular uptake and cell viability differently. In this work, we focus on the syntheses of magnetic nanocomposites in size range of 20–150 nm which was claimed to be the best size range of nanomaterial for biological applications [3]. These size series of MNCPs in this work can be useful tools for understanding the effect of sizes, surfaces, and magnetization in these applications as well as in magnetic separation and magnetically-guided drug delivery systems. 2. Materials and Methods 2.1 Materials Oleic acid, octadecene, sodium hydroxide (NaOH), polyoxyethylene (5) nonylphenylether (Igepal co-520), 1-hexanol, triton x-100, 12-hydroxydodecanoicacid, hydroxyl cellulose (HCP), 5-Amino-1-pentanol (AP) and (3-aminopropyl)triethoxysilane (APS) were purchased form Sigma-aldrich. 2-bomobytyl bromide, ammonium hydroxide and tetraethyl orthosilicate (TEOS) were purchased form Merck.Iron(III) chloride and triethylamine were purchased form Riedel de haën. 2.2 Characterization Methods X-ray powder diffraction (XRD) analyse were performed using Rigaku D/MaX-2200 Ultima-plus instrument with Cu K radiation (1.5418 Aͦ) source (40kV, 30mA). The powdered samples were placed on glass holder. The scans were performed at 25 °C in steps of 0.03° over 2-theta range from 20° to 70°. The size and shape of MNPs and MNCPs in this wok were monitored by JEM-2010 transmission electron microscopy (TEM). The dispersed sample of MNCPs was dispersed on carbon film on 300 mesh copper grids. Fourier transform infrared spectra were recorded on Nicolet 6700 FT-IR spectrometer. The powdered samples were mixed with KBr (ratio 1:1000). 2.3 Synthesis of core-shell MNP@SiO2 Magnetic nanoparticles (MNPs) were prepared using a thermal decomposition technique [4]. Iron oleate was heated above 290 oC. A micelle solution [5] was prepared by mixing Igepalco-520 (20.0 mL) with cyclohexane (100 mL), followed by an addition of the synthesized-MNPs (110 mg in 1 mL of cyclohexane) and 25% ammonium hydroxide (2.00 mL) sequentially. Then, TEOS (0.500 or 3.20 mL) was added in the micelle solution. The reaction mixture was stirred for 24 hours. Finally, it was centrifuged and the resulting solid was washed with ethanol (3 x 40.0mL) to afford the MNP@SiO2 nanoparticles (2.13g). The schematic diagram of this process is shown in Figure 1A. 2.4 Synthesis of silica-MNPs (SiO2-MNP) MNCPs Synthesis of silica NPs was done by reverse emulsion method. For the formation of emulsion, a mixture of 1-hexanol (12.0 mL), triton x-100 (25.0 mL) and cyclohexane (75.0 mL) was sonicated for 20 minutes followed by an addition of DI water (6 mL). Then, the mixture was stirred for an hour, after which ammonium hydroxide (1.25 mL) was added. After an hour of stirring, TEOS (3.20 mL) was added and the solution was stirred for 24 hours. After that it was centrifuged. The resulting solid was washed with ethanol (3 x 40.0 mL). At the end of this process, pure silica NPs was obtained. To prepare the MNP solution [6], MNPs were first washed with ethanol several times. To a 0.500mL ethanol dispersion of MNPs was added 12hydroxydodecanoic acid (100 mg). The mixture was sonicated for an hour, after which AP (400 mg) and Pure and Applied Chemistry International Conference 2015 (PACCON2015) 195 APS (0.823 g) were added. After 4 hours of stirring, the MNP solution was obtained. To an ethanol solution (20.0 mL) of dispersed silica (SiO2) NPs (100 mg) was added hydroxyl cellulose (HCP) (20.0 mg).Then, after an hour of sonication, the MNP solution (50.0–300 µL) was added. The mixture was then stirred for 30 minutes at room temperature. After that, water (50.0 µL), NH4OH (50.0 µL) and TEOS (50.0 µL) were added, respectively. After 8 hours of stirring, SiO2-Fe3O4MNCPs were washed with ethanol (5 x 40.0mL) and kept as an ethanol solution. This process was illustrated in Figure 1B. Fe3O4 MNCPs were compared with both of standard patternJCPDS 19-0629 and JCPDS 29-0085 (amorphous silica). All of MNP@SiO2 and SiO2Fe3O4MNCPs show peak at 2-theta 35.42°, 43.06° and 62.12°. These peaks indicate that these MNCPs contain magnetite. Moreover, Peak at 2-theta 22.48°can be observed and implies that these MNCPs contain amorphous silica as well. The compared result shows all of MNCPs contain both of magnetite and amorphous silica. The IR spectrum of MNP@SiO2(Figure3a)contains an absorption band corresponding to a Si-O-Si stretching at 1070cm-1, which indicates that MNPs were successfully coated with silica. Transmission electron microscopy (TEM) was used to characterize the size of all magnetic nanoparticles (MNPs, MNP@SiO2MNCPs, and SiO2Fe3O4MNCPs).TEM image of MNPs (Figure 4a)shows particle sizes with diameters of about 10 nm, while the MNPs coated with silica exhibit larger particle sizes of around 20 and 40 nm, as shown in Figure 4b and 4c, respectively. The difference in MNP@SiO2 sizes was based on the amount of TEOS used during the synthesis. In particular, 0.500and 3.20 mL of TEOS produced 20 and40 nm MNPs@SiO2, respectively. Figure 1. Synthesis of core-shell MNP@SiO2MNCPs(A), Synthesis of SiO2Fe3O4MNCPs (B) 3. Results and Discussion Thesynthesizedmagnetite(MNPs) was characterized by X-ray diffraction (XRD) analysis,and the resulted XRD pattern was shown in Figure 2. Figure 3.The IR spectrum of MNPs@SiO2 Figure 2.The XRD pattern of the synthesized magnetic nanoparticles (MNPs)(black), M@SiO2 (M@S-20 (blue), M@S-40 (orange) for the sizes of 20 and 40 nm in diameter, respectively.) and SiO2-M MNCPs (SMS; pink)compared with the standard patternfile JCPDS 19-0629(red)and JCPDS 29-0085 (green) Compared with the standard pattern JCPDS 19-0629, the XRD pattern of the MNPs indicates a crystalline structure of Fe3O4 or magnetite. In addition, the XRD pattern of both different size of MNP@SiO2and SiO2- On the other hand, the TEM image of SiO2Fe3O4MNCPs (Figure 4e) reveals the particle size of approximately 120±18 nm in diameter. In addition, all magnetic nanoparticles have narrow size distribution or monodispersity. Monodispersity of these nanoparticles allows usto further apply such magnetic nanocomposites for the study of size effect in biological systems. Moreover, well-dispersity of the MNCPs is claimed to have advantage in preventing agglomeration that could impede activities in biological applications.[7] Pure and Applied Chemistry International Conference 2015 (PACCON2015) 196 c b a d e Figure4.TEM images of MNPs (a), MNP@SiO2 (b) and (c), pure silica (d) and SiO2-Fe3O4MNCPs(e) 4. Conclusions From this work, magnetic nanocomposite size series in the range of 20–150 nm were synthesized successfully via two synthetic pathways, core-shell synthesis and attachment on silica. These size series of magnetic nanocomposites in this work can be useful tools to understand the effects of sizes, surfaces, and magnetization in biological applications in our future study. Acknowledgements This work was funded in part though the Thailand Research Fund (MRG5680091) and partly by the Grants for Development of New Faculty Staff, Ratchadaphiseksomphot Endowment Fund, Chulalongkorn University, and the Science Achievement Scholarship of Thailand (SAST) and we would like to thank Department of Chemistry, Faculty of Science, Chulalongkorn University for laboratory facilities and instruments. References [1] Yanhui, J., Mei Y., Huidong Y., Xinglu H., Xiang S., Xuemei C., Fangqiong T., Jiang P., Jiying C., Shibi L., Wenjing X., Li Z. and Quanyi, G., 2012, International Journal of Nanomedicine, 7, 1697–1708. [2] Zou, P., Yu, Y., Wang, Y. A., Zhong, Y., Welton, A., Galba´n, C., Wang, S. and Sun, D., 2010, Molecular Pharmaceutics, 7, 1974–1984. [3] Hu, F., Neoh, G.K., Cen, L. and Kang, E.T., 2006, Biomacromolecules, 7, 809–816. [4] Park, J., An, K., Hwang, Y., Park, J., Noh, H., Kim, J., Park, J., Hwang, N. and Hyeon, T., 2004, Nature Materials, 3, 891–895. [5] Yi, K.D., Lee, S.S., Papaefthymiou, G.C. and Ying, J.Y., 2006, Chemistry of Material, 18, 614–619. [6] Insin, N., Tracy, B.J., Lee, H.,Zimmer, P.J., Westervelt, M.R. and Bawendi G.M., 2008, ACS Nano, 2, 197–02. [7] Kim, C., Lee, B.,Park, Y., Park, B.,Lee, J. and Kim, H., 2007, Appl. Phys., 91, 113101. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 197 PREPARATION OF PERCHLORTE ANION SELECTIVE MEMBRANE ELECTRODES FROM DONNAN EXCLUSION FAILURE PHENOMENON INDUCED BY METAL IONS Sutida Jansod1, Praput Thavoryutikarn2, Wanwisa Janrungroatsakul3, Wanlapa Aeungmaitrepirom1, Thawatchai Tuntulani1* 1 2 Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50002, Thailand 3 Department of Chemistry, Faculty of Science, Naresuan University, Phitsanulok 65000, Thailand * E-mail for Corresponding Author; E-mail: [email protected] Abstract: A calix[4]arene derivative, tripodal amine crown ether calix[4]arene, L1, was synthesized and used as ionophore or ion carrier which incorporated in the onitrophenyl octyl ether (o-NPOE) plasticized PVC membrane ion selective electrodes (ISE). The prepared ion selective membrane also contained potassium tetrakis(p-chlorophenyl)borate (KTpClPB) as anionic additive. The membrane containing L1 showed Donnan exclusion failure because the ionophore bound tightly to metal ions such as Cu2+ and Zn2+ ions. The influence of positive charges of metals could induce the co-extraction of anions into the membranes that changed the permselectivity of the membrane to the negative direction. The fabricated electrodes containing L1 with KTpClPB as anionic additive preconditioning in CuCl2 and ZnCl2 illustrated the highest selectivity toward perchlorate with slopes of -56.11 and -56.58 mV decade-1, respectively over a wide concentration range of ClO4(10-5 to 10-2 M) with detection limits as low as 2.88 x 10-6 and 2.78 x 10-6 M, respectively. In addition, the fabricated membrane electrodes could be used in a wide pH range with good ISE characteristics. often bound metal ions very strongly. Polymeric membrane containing L1 possessing only one tripodal amine receptor was prepared to study the complex stability and selectivity toward anions. When the ionophore bound very tightly and stably with metal ions, the polymeric membrane stored many positive charges from metal ions. To balance the positive charges, the membrane induced the co-extraction of anions entirely into the membrane (Figure 1). This phenomenon is called Donnan exclusion failure [1114]. The permselectivity of the membrane was then changed to the opposite direction. 1. Introduction Figure 1. Concept of Donnan exclusion failure Ion selective electrodes (ISEs), a potentiometric sensor, have been widely used as analytical devices for the determination of an extensive range of ions in environmental and clinical analysis as well as in the process control [1-5]. In order to achieve highly selective ISEs on the basis of PVC membrane, suitable ionophores must be doped into the membrane. Thus far, derivatives of calix[4]arene have been used as ionophores in ISEs [6-10] due to their high lipophilicity and robust structures. In this work, we have fabricated new perchlorate anion detectors by using calix[4]arene derivative, mono-tripodal amine crown ether calix[4]arene (L1), in a conventional ISE platform. The topology of the receptor is of importance in determining the overall receptor-ion interactions. Tripodal amine receptor is a class of acyclic ionophore, which consists of multiarmed ligands with each arm bearing a functional group that can coordinate with the target ion. Currently, the tripodal amine-based receptor has been used as a recognition motif successfully in ionselective electrode membranes [8,11]. According to the enhanced chelating effects, the tripodal receptor 2. Materials and Methods 2.1 Synthesis Calix[4]arene derivative, mono-tripodal amine crown ether calix[4]arene (L1) was synthesized according to the procedures described previously [15]. 2.2 Reagents High molecular weight poly(vinyl chloride) (PVC), o-nitrophenyl octyl ether (o-NPOE), Potassium tetrakis(p-chlorophenyl)borate (KTpClPB), Tetrahydro furan (THF) and dichloromethane (CH2Cl2) were all purchased from Fluka. Analytical grade of sodium and potassium salts of the anions were from BHD, Fluka, Carlo Erba, and Merck. All solutions were also prepared with ultrapure water from Milli-Q. 2.3 Membrane preparation The membrane was mixed and stirred with a total amount of 220 mg consisted of ionophore (10 mmol kg-1), various amount of the ion exchanger, KTpClPB, (25, 50, and 75 mol% relative to the ionophore) and PVC: o-NPOE plasticizer (1:2 w/w). The membrane Pure and Applied Chemistry International Conference 2015 (PACCON2015) 198 containing L1 was dissolved in the minimum amount of dichloromethane. After that, the components were dissolved totally into 2.5 mL of THF. The mixtures were dispensed as a thin film on a glass slide. 2.4 The EMF measurement The preconditioned membrane was attached to an electrode body as working electrode that conditioned in 10-2 M of metal chloride solution overnight before measuring with anions. The electrode was also filled with primary anion (10-2 M) and NaCl (10-3 M) as an inner filling solution. A double junction Ag/AgCl/KCl 3M electrode containing 1 M LiAcO electrolyte bridge was used as reference electrode. The EMF values and the activity coefficients were recorded and calculated. 2.5 Selectivity measurement: The potentiometric selectivity coefficients of the electrodes were examined by using the separate solution method (SSM) as recommended by the IUPAC [12]. The SSM was the measurement of two separate solutions, both containing calibration curves of interfering and primary anions at the concentration range from 10-7 to 10-2 M. The selectivity coefficients were calculated from the observed EMF values. 3. Results and Discussion Polymeric membrane containing calix[4]arene derivative, mono-tripodal amine crown ether calix[4]arene (L1), was used to fabricate conventional ISE, the structures of L1 was shown in Figure 2. The properties of L1 as ion carrier based on PVC membrane were first determined by investigating the potentiometric responses toward cations. The membranes containing L1 which possessing only one unit of the receptor gave negative EMF responses to most cations, the results were shown in Table 1. This is a consequence of the formation of too strong complexes inducing the co-extraction of anions into the membranes. In addition, the permselectivity of the membranes was changed from cations to anions, so called Donnan exclusion failure. Considering the membranes which nearest to the theoretical Nernstian slopes, Cu(II) and Zn(II) were chosen for the following experiments using membrane compositions shown in Table 2. Table 1: Potentiometric cation responses of the membrane containing L1 IFS Linear range (10-2 M) (M) Cu(NO3)2 CuCl2 10-3 – 10-2 Zn(NO3)2 ZnCl2 10-3 – 10-2 Ni(NO3)2 NiCl2 10-3 – 10-2 Co(NO3)2 CoCl2 10-4 – 10-2 Cd(NO3)2 CdCl2 10-3 – 10-2 NaNO3 NaCl 10-3 – 10-2 KNO3 KCl 10-3 – 10-2 AgNO3 AgNO3 10-4 – 10-3 Mg(NO3)2 MgCl2 10-3 – 10-2 Ca(NO3)2 CaCl2 10-4 – 10-3 Hg(NO3)2 HgCl2 10-5 – 10-4 Pb(NO3)2 PbCl2 10-4 – 10-3 IFS: The inner filling solution Samples Slope (mV decade-1) -59.77 ±1.22 -61.52 ±0.86 -54.01 ±1.41 -20.92 ±0.45 -31.26 ±2.21 -41.79 ±1.58 -35.64 ±1.59 -53.64 ±2.86 -45.68 ±3.14 -6.73 ±0.54 -22.83 ±0.58 -51.47 ±0.77 In addition, we compared the selectivity coefficients of anions using the separate solution method (SSM). The results demonstrated in Figure 3 that both membranes were the most selective to perchlorate, which followed lipophilicity of anions. As we have known that, the membrane composition used can influence the response performance such as the selectivity, linear concentration range, a detection limit and a response time of polymeric ion-selective electrode. The further fabricated electrodes containing L1 with KTpClPB as anionic additive preconditioning in CuCl2 (electrode1) and ZnCl2 (electrode2) showed the highest selectivity toward perchlorate with slopes of -56.11 and -56.58 mV decade-1, respectively over a wide concentration range of ClO4- from 10-5 – 10-2 M with detection limits as low as 2.88 x 10-6 and 2.78 x 10-6 M, respectively. Moreover, the time trace line of the optimize electrode1 toward perchlorate was shown in Figure 4. Figure 3. A comparison of the selectivity coeffcients of the membranes of L1 preconditioning in CuCl2 (a) and ZnCl2 (b) Figure 2. Structure of mono-tripodal amine crown ether calix[4]arene (L1) Pure and Applied Chemistry International Conference 2015 (PACCON2015) 199 Table 2: Membrane compositions and electrode properties of the conventional ISE of L1 toward perchlorate KTpClPB (mol%) 24.7 50.0 75.1 Linear Range(M) 10-5 – 10-2 10-5 – 10-2 10-5 – 10-2 Slope (mVdecade-1) -56.19 ±0.40 -55.06 ±1.05 -48.10 ±0.82 DL (µM) 3.09 3.70 5.38 CuCl2 24.7 50.0 75.1 10-5 – 10-2 10-5 – 10-2 10-5 – 10-2 -55.80 ±0.36 -56.11 ±0.36 -51.19 ±0.38 2.84 2.88 3.35 Cu(NO3)2 24.7 50.0 75.1 10-5 – 10-2 10-5 – 10-2 10-5 – 10-2 -55.12 ±0.31 -53.76 ±0.66 -50.40 ±1.73 2.86 3.33 4.14 Zn(ClO4)2 25.7 50.0 75.1 10-5 – 10-2 10-5 – 10-2 10-5 – 10-2 -55.69 ±0.33 -55.90 ±0.48 -52.95 ±1.10 3.45 3.26 3.64 ZnCl2 25.7 50.0 75.1 10-5 – 10-2 10-5 – 10-2 10-5 – 10-2 -56.58 ±0.52 -55.90 ±0.33 -51.39 ±0.74 2.78 2.80 3.47 Zn(NO3)2 25.7 50.0 75.1 10-5 – 10-2 10-5 – 10-2 10-5 – 10-2 -55.39 ±0.37 -56.27 ±0.16 -50.84 ±0.57 3.29 3.24 3.31 Condition Cu(ClO4)2 Figure 6. pH effect on potentiometric responses of the optimized electrode1 toward 10-3 to 10-2 M of perchlorate The performance of the new electrodes also showed good reversibility of the optimized perchlorate-ISEs by switching the concentrations of perchlorate from 10-3 to 10-2 M (Figure 5). The membranes can be further used in a wide pH range (Figure 6). 4. Conclusions Figure 4. Time-dependent response of the optimized electrode1 toward perchlorate Mono-tripodal amine crown ether calix[4]arene, L1, was successfully synthesized and used as ion carrier in polymeric membrane electrodes. The membrane containing L1 demonstrated the Donnan exclusion failure upon binding metal ions tightly and induced anions into the membranes that changed the permselectivity of the membrane into the negative direction. The fabricated new perchlorate-selective electrodes using Cu(II) and Zn(II) as effectors illustrated the Nernstian slopes of -56.11 and -56.58 mV decade-1, detection limits as low as 2.88 x 10-6 and 2.78 x 10-6 M with good ISE characterictics. Acknowledgements The authors would like to thank Development and Promotion of Science and Technology talents project (DPST) and the Thailand Research Fund (RTA5380003) for financial support. References Figure 5. Reversibility of the optimized electrode1 for 10-3 to 10-2 M of perchlorate [1] Bakker, E., Bühlmann, P. and Pretsch, E., 1997, Chem. Rev., 97, 3083–3132. [2] Bellavista, A., Macanas, J. And Fabregas E., 2007, Sens. Actuators, B., 125, 100–105. [3] Bakker, E., Pretsch, E. and Bühlmann, P., 2000, Anal. Chem., 72, 1127–1133. [4] Hassan, S., Ghalia, A., Amr, A. and Mohamed A., 2003, Anal. Chim. Acta., 482, 9–18. [5] Wongsan, W., Aeungmaitrepirom, W., Chailapakul, O., Ngeontae, W. And Tuntulani, T., 2013, Electrochim. Acta., 111, 234–241. [6] Ngeontae, W., Janrungroatsakul, W., Morakot, N., Aeungmaitrepirom, W. and Tuntulani, T., 2008, Sens. Actuators, B., 134, 377–385. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 200 [7] Ngeontae, W., Janrungroatsakul, W., Maneewattana pinyo, P., Egkasit, S., Aeungmaitrepirom, W. and Tuntulani, T., 2009, Sens. Actuators, B., 137, 320–326. [8] Khamjumphol, U., Watchasit, S., Suksai, C., Janrungroatsakul, W., Boonchiangma, S., Tuntulani, T. And Ngeontae, W., 2011, Anal. Chim. Acta., 704, 73– 86. [9] Janrungroatsakul, W., Vilaivan, T., Vilaivan, C., Watchasit, S., Suksai, C., Ngeontae, W., Aeungmaitrepirom, W. and Tuntulani, T., 2013, Talanta., 105, 1–7. [10] Kivlehan, F., Mace, W., Moynihan, H. And Arrigan, D., 2007, Anal. Chim. Acta., 585, 154–160. [11] Kunthadee, P., Watchasit, S., Kaowliew, A., Suksai, C., Wongsan, W., Negontae, W., Chailapakul, O., Aeungmaitrepirom, W. and Tuntulani, T., 2013, New J. Chem., 37, 4010–4017. [12] Buck, R. and Linder, E., 1994, Pure Appl. Chem., 66, 2527–2536. [13] Buck, P., Cosofret, V. and Linder, E., 1993, Anal. Chim. Acta., 282, 273–281. [14] Buck, P., Graf, E., Horvai, G. and Pungor, E., 1987, J. Electroanal. Chem., 223, 51–66. [15] Tuntulani, T., Thavornyutikarn, P. Poompradub, S., Jaiboon, N., Ruangpornvisuti, V., Chaichit, N., Asfari, Z. And Vicens, J. 2002, Tetrahedron., 58, 10277– 10285. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 201 BIMETALLIC ALUMINUM COMPLEXES SUPPORTED BY METHYLENE BRIDGED BIS(PHENOXY-IMINE) LIGANDS FOR THE ROP OF RAC-LACTIDE Nattawut Yuntawattana, Pimpa Hormnirun* Department of Chemistry, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand * E-mail [email protected], Tel. +66 2562 5555 ext. 2168 Abstract: A series of bimetallic aluminum complexes bearing methylene bridged bis(phenoxy-imine) ligands (1-3) have been successfully synthesized and characterized by NMR spectroscopy. The complexes were obtained in good yields by the reaction between the corresponding ligand and 2 equivalents of trimethyl aluminum (TMA) in toluene at 90 oC. All bimetallic aluminum complexes were efficient initiators for the ring-opening polymerization of rac-lactide and the polymerizations proceeded in a controlled manner. Kinetic studies revealed that all polymerizations were first-order kinetics in monomer. The plots between molecular weight versus conversion exhibited a good linear relationship suggesting the living polymerizations. In addition, the imino substituents on the ligand framework and the ortho phenoxy substituents have significant impacts on the catalytic activities and the stereoselectivity of catalysts. 1. Introduction Polylactides (PLA), aliphatic polyesters derived from lactide (LA) monomers, have received great attention over the past two decades. Owing to their biocompatible and biodegradable properties, PLA can be applied to use in many applications, for instance, suture and fixing bone in biomedical applications and drug delivery in pharmaceutical applications. [1] Generally, high-molecular weight PLA with narrow polydispersity index can be produced by the ring-opening polymerization (ROP) using single-site catalysts as initiators. [2] The general formula of catalysts is LnMOR where Ln is an ancillary ligand, OR is an initiating group and M is a metal center. So far, many complexes of metals such as Zn, [3] Fe, [4] Sn, [5] Ca, [6] Li [7] and Al [2a, 8] have been reported to promote the ROP of lactide. However, the most promising candidate for industrial features is an aluminum metal because of no toxicity. In the last two decades, there have been many examples of the application of aluminum complexes as initiators for the ROP of rac-lactide (rac-LA). However, only a limited example of bimetallic aluminum complexes has been published. For example, Wang et al. reported that dinuclear aluminum complexes suppoted by amino or iminophenolate ligands are efficient catalysts for the ROP of rac-LA. [9] Haiyan Ma et al. proved that dinuclear salan aluminum complexes are active initiators for the ROP of rac-LA and ε-caprolactone (ε-CL) to give copolymers between rac-LA and ε-CL with different microstructures. [10] Herein, we reported the synthesis and characterization of a new series of bimetallic aluminum complexes supported by methylene-bridged bis(phenoxy-imine) ligands and their application as initiators in the ROP of rac-LA 2. Materials and Methods Ligand syntheses Synthesis of [4-OH-3-{CH=N(C6H5)}-C6H3]2CH2 (a) To a stirred solution of 5,5´-methylene bis(2hydroxy benzaldehyde) (2.00 g, 7.80 mmol) in ethanol (25 mL) was slowly added aniline (1.45 g, 15.61 mmol) at room temperature. A catalytic amount of formic acid was then added. The reaction mixture was stirred at room temperature for 24 hours during which time an orange solid precipitated. The product was filtered and dried in vacuo. Yield: 2.49 g, 79% 1 H NMR (500.13 MHz, CDCl3): δ 13.14 (2H, s, OH), 8.53 (2H, s, NCH), 7.38 (4H, t, 3JHH = 7.8 Hz, ArH), 7.29.7.17 (8H, m, ArH), 7.14 (2H, d, 4JHH = 2.1 Hz, ArH), 6.96 (2H, d, 3JHH = 8.4 Hz, ArH), 3.90 (2H, s, CH2). 13 C NMR (125.77 MHz, CDCl3): δ 162.6 (NCH), 159.6 (ArCOH), 148.4 (ArC), 133.7 (ArCH), 132.1 (ArCH), 131.6 (ArC), 129.3 (ArCH), 126.9 (ArCH), 121.1 (ArCH), 119.0 (ArC), 117.3 (ArCH), 39.6 (CH2). Synthesis of [4-OH-3-{CH=N(2,6-iPr2C6H3)}C6H3]2CH2 (b) The synthesis of b was carried out by the same procedure as that of a, except 2,6-diisopropyl aniline (2.77 g, 15.61 mmol) was used. The product was obtained as a pale yellow solid. Yield: 1.95 g, 87% 1 H NMR (500.13 MHz, CDCl3): δ 12.98 (2H, s, OH), 8.26 (2H, s, NCH), 7.30-7.23 (2H, m, ArH), 7.22-7.12 (8H, m, ArH), 7.02 (2H, d, 3JHH = 8.5 Hz, ArH), 3.95 (2H, s, CH2), 2.98 (2H, sept, 3JHH = 6.8 Hz, CH(CH3)2), 1.17 (24H, d, 3JHH = 6.8 Hz, CH(CH3)2). 13 C NMR (125.77 MHz, CDCl3): δ 166.5 (NCH), 159.6 (ArCOH), 146.2 (ArC), 138.7 (ArC), 133.8 (ArCH), 132.0 (ArCH), 131.6 (ArC), 125.4 (ArCH), 123.2 (ArCH), 118.5 (ArC), 117.4 (ArCH), 39.9 (CH2), 28.1 (CH(CH3)2), 23.4 (CH(CH3)2). Pure and Applied Chemistry International Conference 2015 (PACCON2015) 202 Synthesis of [4-OH-5-tert-butyl-3-{CH=(N2,6i Pr2C6H3)}-C6H3]2CH2 (c) The synthesis of c was carried out by the same procedure as that of a, except 5,5´-methylene bis(3tert-butyl-2-hydroxy benzaldehyde) (2.00 g, 5.43 mmol) and 2,6-diisopropyl aniline (1.94 g, 10.91 mmol) was used. The product was obtained as a pale yellow solid. Yield: 2.98 g, 80% 1 H NMR (500.13 MHz, CDCl3): 13.45 (2H, s, OH), 8.25 (2H, s, NCH), 7.33 (2H, d, 4JHH = 2.2 Hz, ArH), 7.20-7.15 (6H, m, ArH), 6.99 (2H, d, 4JHH =2.2 Hz, ArH), 3.93 (2H, s, CH2), 2.99 (2H, sept, 3JHH = 6.9 Hz, CH(CH3)2), 1.48 (18H, s, CH(CH3)3), 1.17 (24H, d, 3 JHH = 6.9 Hz, CH(CH3)2). 13 C NMR (125.77 MHz, CDCl3): 167.2 (NCH), 159.0 (ArC), 146.3 (ArC), 138.8 (ArC), 137.9 (ArC), 131.2 (ArCH), 130.5 (ArC), 130.1 (ArCH), 125.3 (ArCH), 123.2 (ArCH), 118.3 (ArC), 40.4 (CH2), 35.0 (C(CH3)3), 26.4 (CH3), 29.4 (CH3), 28.0 (CH), 23.6 (CH3). Complex syntheses Synthesis of [4-(OAlMe2)-3-{CH=N(C6H5)}C6H3]2CH2 (1) To a stirred solution of 5,5´-methylene bis(2hydroxy benzaldehyde) (1.00 g, 2.46 mmol) in toluene (15mL) was slowly added TMA (2.46 mL of a 2.0 M solution in toluene, 4.92 mmol) at 0 oC. The reaction was stirred at 90 oC for 24 hours during which time an orange precipitate formed. The orang solid was then filtered and dried in vacuo. Yield: 0.51 g, 40% 1 H NMR (500.13 MHz, CDCl3): δ 8.25 (2H, s, NCH), 7.51-7.42 (4H, m, ArH), 7.42-7.31 (4H, m, ArH), 7.31-7.21 (2H, m, ArH), 7.21-7.13 (2H, m, ArH), 7.04 (2H, s, ArH), 6.90 (2H, d, 3JHH = 8.6 Hz, ArH), 3.85 (2H, s, CH2), -0.74 (12H, s, Al(CH3)2). 13 C NMR (125.77 MHz, CDCl3): δ 169.5 (NCH), 138.9 (ArC), 134.6 (ArC), 129.8 (ArCH), 128.7 (ArC), 128.2 (ArCH), 128.1 (ArCH), 128.0 (ArCH), 125.3 (ArC), 123.6 (ArCH), 122.2 (ArCH), 39.3 (CH2), -9.4 (Al(CH3)2). Synthesis of [4-(OAlMe2)-3-{CH=N(2,6-iPr2C6H3)}C6H3]2CH2 (2) Complex 2 was prepared according to the same procedure as that of 1. The product was obtained as a pale yellow solid. Yield: 0.50 g, 41% 1 H NMR (500.13 MHz, CDCl3): δ 8.03 (2H, s, NCH), 7.37 (2H, dd, 4JHH = 2.3 Hz, 3JHH = 8.6 Hz, ArH), 7.33 (2H, d, 4JHH = 7.5 Hz, ArH), 7.25 (4H, d, 3JHH = 7.8 Hz, ArH), 6.99 (2H, d, 4JHH = 2.1 Hz, ArH), 6.96 (2H, d, 3JHH = 8.6 Hz, ArH), 3.87 (2H, s, CH2), 3.06 (4H, sept, 3JHH = 6.8 Hz, CH(CH3)2), 1.28 (6H, d , 3JHH =6.8 Hz, CH(CH3)2), 1.07 (6H, d, 3JHH = 6.8 Hz, CH(CH3)2), -0.78 (12H, s, Al(CH3)2). 13 C NMR (125.77 MHz, CDCl3): δ 172.7 (NCH), 163.7 (ArC), 142.3 (ArCH), 141.8 (ArC), 138.9 (ArCH), 134.2 (ArC), 129.9 (ArC), 128.2 (ArCH), 124.2 (ArCH), 122.4 (ArCH), 118.4 (ArC), 39.2 (CH2), 28.2 (CH(CH3)2), 26.0 (CH(CH3)2), 22.6 (CH(CH3)2), -10.0 (Al(CH3)2). Synthesis of [4-(OAlMe2)-5-tert-butyl-3-{CH=N2,6i Pr2C6H3)}-C6H3]2CH2 ( 3) Complex 3 was prepared according to the same procedure as that of 1. The product was obtained as a pale yellow solid. Yield: 0.50 g, 41% 1 H NMR (500.13 MHz, CDCl3): δ 7.88 (2H, s, NCH), 7.32 (2H, s, ArH), 7.26-7.20 (2H, m, ArH), 7.19-7.12 (4H, m, ArH), 6.69 (2H, s, ArH), 3.75 (2H, s, CH2), 2.98 (4H, sept, 3JHH = 6.8 HZ, CH(CH3)2), 1.34 (18H, s, C(CH3)3), 1.18 (6H, d, 3JHH = 6.8 Hz, CH(CH3)2), 0.96 (6H, d, 3JHH = 6.8 Hz, CH(CH3)2), -0.88 (12H, s, Al(CH3)3) 13 C NMR (125.77 MHz, CDCl3): δ 173.4 (NCH), 163.1 (ArC), 142.5 (ArCH), 142.1 (ArC), 141.7 (ArC), 135.8 (ArCH), 132.3 (ArC), 128.8 (ArC), 128.0 (ArCH), 124.2 (ArCH), 118.5 (ArC), 39.9 (CH2), 29.3 (C(CH3)3), 28.1 (CH(CH3)2), 26.1 (CH(CH3)2), 22.7 (CH(CH3)2), -9.8 (Al(CH3)2). 3. Results and Discussion Synthesis and Characterization of aluminum methyl complexes 1-3 The methylene bridged bis(phenoxy-imine) ligands (a-c) were successfully synthesized by a Schiff-base condensation between one equivalent of 5,5´-methylenebis(2-hydroxy benzaldehyde) or 5,5´methylenebis(3-tert-butyl-2-hydroxy benzaldehyde) and two equivalents of the primary amine derivative in ethanol at room temperature, as shown in Scheme 1. All ligands were obtained in high yields (79-87%). Treatment of the ligand with two equivalents of trimethyl aluminum (TMA) in anhydrous toluene at 90 o C afforded the corresponding bimetallic aluminum complexes (1-3) in quantitative yields (40-41%). The complexes were formulated on the basis of 1H and 13C NMR spectroscopy. Solution 1H NMR studies revealed that the formation of aluminum complexes 1-3 from the disappearance of the OH signal of the free ligands and the appearance of methyl protons attached to the aluminum center in the high field region of the 1H NMR spectra, which is characteristic of an aluminummethyl group. In all cases, an integral ratio of methylene protons to aluminum methyl protons is 1:12, indicating the formation of bimetallic aluminum complexes. R2 R2 O N O CH2 HO R1 OH + R2NH2 N Ethanol CH2 HO R1 R1 OH R1 a: R1 = H; R2 = C6H6 b: R1 = H; R2 = 2,6-iPr2C6H4 c: R1 = tBu; R2 = 2,6-iPr2C6H4 2AlMe3 Me Toluene R2 R2 N N Me Me Al Al CH2 O 1 R O Me 1: R1 = H; R2 = C6H6 2: R1 = H; R2 = 2,6-iPr2C6H4 3: R1 = tBu; R2 = 2,6-iPr2C6H4 1 R Scheme 1. Synthetic pathway of complex 1-3. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 203 8000 3.0 6000 2.5 4000 2.0 Aliquots periodically withdrawn from the polymerization reactions of rac-LA with 1-3 were used to construct plots of molecular weight versus percent conversion of monomer. A linear correlation between molecular weight and percent conversion, in conjunction with a narrow PDI was observed in all cases (Figure 1), which is indicative of a well– controlled living polymerization and a single-site reaction. In addition, the observation of relatively narrow and constant PDI values throughout the course of polymerization suggests that no significant degree of tranesterifications operates in this initiating system 3.5 (a) 3.0 2.5 Ln[LA]0/[LA]t Ring-opening polymerization of rac-lactide The ROP of rac-LA using complexes 1-3 were carried out in toluene at 70 oC in the presence of two equivalents of benzyl alcohol to form an in situ aluminum alkoxide species. The results are summarized in Table 1. All complexes were effective for the polymerization of rac-LA. The molecular weights and the PDI values were determined by gel permeation chromatography (GPC) using the MarkHouwink correction factor of 0.58. [2a] The corrected Mn values (entries 1-3) closed to the theoretical values and narrow PDIs on indicative of living characteristic. The polymerization using 1 and 2 proceeded to 98 and 99% conversion, respectively, in 24 h (entries 1 and 2) whereas 3 polymerized rac-LA to 87% conversion after 96 h (entry 3). (a) 2.0 1.5 1.0 PDI Mn .5 0.0 0 2000 1.5 0 1.0 100 10000 20000 30000 40000 50000 60000 Time (s) 2.0 0 20 40 60 80 (b) 1.8 1.6 Conversion (%) 8000 Ln[LA]0/[LA]t 3.0 (b) 6000 2.5 4000 2.0 1.4 1.2 1.0 .8 .4 PDI Mn .6 .2 0.0 2000 0 1.5 5000 10000 15000 20000 25000 30000 35000 Time (s) 0 0 20 40 60 1.8 1.0 100 80 (c) Conversion (%) 1.4 Ln[LA]0/[LA]t (c) 2.0 4000 PDI 2.5 6000 Mn 1.6 3.0 8000 1.2 1.0 .8 .6 .4 .2 2000 1.5 0 1.0 100 0.0 0 50000 100000 150000 200000 250000 300000 Time (s) 0 20 40 60 80 Figure 2. Semilogarithmic plots of rac-lactide conversion versus time in toluene at 70 ºC with (a) complex 1a and (b) complex 2a (c) complex 3a ([LA]0/[Al] = 100, [Al]/[PhCH2OH] = 1, [LA]0 = 0.42 M, [Al] = 8.33 mM). Table1. Polymerization results of rac-lactide by complexes 1-3a Conversion (%) Figure 1. Plots of PLA Mn (●) and PDI (○) as a function of monomr conversion for a rac-LA polymerization using (a) 1a/BnOH, (b) 2a/BnOH and (c) 3a/BnOH ([Al]:[BnOH]:[LA]0 = 1:2:100, 70 oC). Entry complex Time (h) Conv. (%)b Mn (GPC)c Mn (Theory)d PDI Pme kapp (s-1) 1 2 1 2 24 24 98 99 7,091 8,467 7,063 7,135 1.33 1.27 0.45 0.34 5.89 × 10-5 6.30 × 10 -5 3 3 96 87 6,024 6,270 1.18 0.55 6.31 × 10-6 a[LA] /[Al] 0 = 100, [Al]/[PhCH2OH] = 0.5, [LA]0 = 0.83 M, toluene, 70 ºC. bAs determined via integration of the methine resonances (1H NMR) of LA and PLA (CDCl3, 400 MHz). cCalculated by ([LA]0/[Al]) × 144.13 × conversion. dDetermined by gel permeation-chromatography (GPC) calibrated with polystyrene standards in THF and corrected by a factor of 0.58 for PLA. ePm is the probability of meso linkage between monomer unit Pure and Applied Chemistry International Conference 2015 (PACCON2015) 204 Kinetic studies of the polymerizations with 1-3 were monitored by 1H NMR spectroscopy. In all cases, kinetics of first-order in monomers were observed, as evidenced from the linear relationship between ln([LA]0/[LA]t) and time, as shown in Figure 2. The apparent rate constant (kapp) were obtained from the gradient of semilogarithmic plots of the rac-LA conversion ln([LA]0/[LA]t) versus time. The polymerization with 1 exhibits a kapp of 5.89 × 10-5 s-1 which is slightly slower than the rate of 2 (6.30 × 10-5 s-1). Complex 3 shows the lowest the polymerization rate (kapp = 6.31 × 10-6 s-1). This may be attributed to the steric protection at the aluminum center be the tertbuthyl at the ortho-position of the phenoxy ring. The microstructure of the PLA samples produced by 1-3 were determined by homonuclear decoupled 1H NMR spectroscopy. It was found that the imino substituent and the ortho phenoxy substituent have some impacts on the stereoselectivity of catalysts. PLA produced by 1 is slightly heterotactic with a Pm value of 0.55 while the use of 2 resulted in a higher heteroselectivity with a Pr value of 0.66. In the case of 3, the slightly isotactic-biased PLA was produced (Pm = 0.55). (b) O'Keefe, B. J., Monnier, S. M., Hillmyer, M. A. and Tolman, W. B., 2000, J. Am. Chem. Soc., 123, 339-340. [5] Kowalski, A., Libiszowski, J., Duda, A. and Penczek, S., 200, Macromolecules, 33, 1964-1971. [6] (a) Zhong, Z., Ankoné, M. J. K., Dijkstra, P. J., Birg, C., Westerhausen, M. and Feijen, J., 2001, Polym. Bull., 46, 51-57 (b) Zhong, Z., Dijkstra, P. J., Birg, C., Westerhausen, M. and Feijen, J., 2001, Macromolecules, 34, 3863-3868. [7] Kricheldorf, H. R. and Boettcher, C., 1993, Die Makromolekulare Chemie, 194, 1665-1669. [8] Hormnirun, P., Marshall, E. L., Gibson, V. C., Pugh, R. I. and White, A. J. P., 2006, Proc. Natl. Acad. Sci. U.S.A., 103, 15343-15348. [9] Yu, X.-F. and Wang, Z.-X., 2013, Dalton Trans., 42, 3860-3868. [10] Wang, Y. and Ma, H., 2012, Chem. Commun., 48, 67296731. 4. Conclusions A new series of bimetallic aluminum complexes bearing methylene bridged bis(phenoxy-imine) ligands were successfully synthesized and characterized by NMR spectroscopy. All complexes were effective initiators for the polymerization of rac-LA and the polymerizations proceeded efficiently in a living manner. Kinetic studies using complexes 1-3 revealed a first-order in monomer in all cases. The rate of polymerization decrease in the order 2 > 1 > 3. Complexes 1 and 2 afforded slightly heterotactic PLAs with the Pr values of 0.55 and 0.66, respectively. A slightly isotactic PLA was produced by 3. Acknowledgements Department of chemistry, the Faculty of Science, Kasetsart University and Development and Promotion of Science and Technology Talents Project are thanked for financial support of this work References [1] (a) Uhrich, K. E., Cannizzaro, S. M., Langer, R. S. and Shakesheff, K. M., 1999, Chem. Rev., 99, 3181-3198 (b) Ikada, Y. and Tsuji, H., 2000, Macromol. Rapid Commun., 21, 117-132. [2] (a) Kowalski, A., Duda, A. and Penczek, S., 1998, Macromolecules, 31, 2114-2122 (b) Löfgren, A., Albertsson, A.-C., Dubois, P. and Jérôme, R., 1995, J. Macromol. Sci. Polymer Rev., 35, 379-418. [3] Schwach, G., Coudane, J.. Engel, R. and Vert, M., 1998, Polymer International, 46, 177-182. [4] (a) O'Keefe, B. J., Breyfogle, L. E., Hillmyer, M. A. and Tolman, W. B., 2002, J. Am. Chem. Soc., 124, 43844393 Pure and Applied Chemistry International Conference 2015 (PACCON2015) 205 GOLD NANOPARTICLES WITH POLYANILINE FOR SELECTIVE COUPLING AND OXIDATION REACTIONS OF ARYL BORONIC AND ITS SUBSTITUTES Vithawas Tungjitgusongun and Ekasith Somsook* NANOCAST Laboratory and Center for Catalysis, Department of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Mahidol University, 272 Rama VI Rd., Thung Phaya Thai, Rachathewi, Bangkok 10400, Thailand * E-mail: [email protected] Abstract: Gold catalysts were investigated for the selective transformation of aryl boronic acids in different pathways: (I) Coupling reaction and (II) Oxidation reaction. Polyaniline and its derivatives were considered as stabilizing ligands of gold nanocatalysts to transform the reaction selectively. In coupling reaction(I), aryl boronic A and B were used as starting materials to study the effect of selective coupling products, homocoupling and cross coupling, resulted from different polyanilines. For (II) oxidation reaction, phenol products were considered as byproducts of the coupling reaction. This research suggested how to tune the catalytic activity of gold nanocatalysts selectively by polyanilines. its derivatives for example poly-(m-aminophenol), in order to obtain more selective products. 2. Materials and Methods 1. Introduction 2.2 Catalyst preparation Polymerization of polyanilines, poly-(maminophenol) and poly-(m-aminoaniline), were prepared by using a simple oxidant, ammonium persulfate, dissolved in 1 M sulfuric acid to gain the polymer. HAuCl4·3H2O was stabilized by polyaniline in water intermediate. The mixing solution of HAuCl4·3H2O and polyaniline should be used freshly after prepared.Gold nanocatalysts were observed by transmission electron microscopy (TEM) technique. Gold nanocatalysts have been used for several years because of their surface activation on nanoscale[1,2]. This metal was abundantly used in many reactions especially coupling reactions and oxidation reactions[3-8]. However the way to keep them in a particle form is significant for each reaction. Reaction of boronic acid and gold catalysts was recently studied[9], not only homocoupling product was found in this reaction but also oxidation of boronic into phenol was occurred too. To study more information of this reaction, cross coupling reaction of boronic acid is considered as studying reaction model because of many kinds of products that can be occurred in the reaction such as cross coupling product: two products from homocoupling and two products from oxidation of boronic acid. Polyaniline plays an important role not only to stabilize this catalysts into the nanoparticle form[10], in which aggregation of catalysts was not observed, but also to be a reducing agent in the reaction. Furthermore, it still can make reaction selective between coupling and oxidation reactions resulting from its steric and electronic effects. Mole ratio between gold and polyaniline and optimization of the ratio has been studied. Besides, type of polyaniline is also significant. Variation of polyaniline has been studied to reveal steric and electronic effects by using 2.1 Materials HAuCl4·3H2O (99.99% purity),2aminophenol (98% purity), m-phenylenediamine (98% purity), phenylboronic acid (98% purity), 2tolylboronic acid (98% purity), 3-tolylboronic acid (98% purity) and 4-tolylboronic acid (98% purity) were purchased from Aldrich. Ammonium persulfate (98% purity) was from Univar. Potassium hydroxide (99.99% purity) and tetrahydrofuran (99.9% purity) were obtained from Merck. Sulfuric acid (>95% purity) was from Fluka. Deionized water was used in all experiments. NH2 (NH 4) 2S2 O8 R H2 SO4 rt, 24 h N H R H N N H R R 2.3 Reaction of boronic acid with gold nanocatalysts Reaction was carried out at room temperature and under atmospheric pressure. 2 mmol of boronic acid A and B and 2% mol of gold nanocatalysts were mixed in tetrahydrofuran solvent, and the ratio between tetrahydrofuran and water was 1:1, with 300% mol of potassium hydroxide as base for 24 h. After finishing the process, the reaction was quenched by 1 M hydrochloric acid until the solution become neutral, pH = 7. Products were obtained by extraction with ethyl acetate. The extracted product was analysed by GC–MS and GC (Agilent Technologies 7890A GC System with a 30 m HP-5 capillary column). Pure and Applied Chemistry International Conference 2014 (PACCON2014) H N R 206 The product consisted of cross coupling product of A and B, homocoupling product of A, homocoupling product of B, oxidation product of A and oxidation product of B depending on the type and the amount of polyaniline. functions: (i) polyaniline interrupts boronic acids in coupling reaction and (ii) transforms boronic acid into phenol. Table 2: Reaction of boronic acid and gold nanocatalysts with poly-(m-aminophenol) 3. Results and Discussion Entry Reactions were carried out at room temperature, 30 °C, under atmospheric pleasure and basic condition. The reaction without polymer (Table 1), ligandless catalysts, gives products that can be freely occurred depending on only steric and electronic effects from starting materials. However, aggregation of gold was found in every reaction. 1 Starting material phenylboronic (A) Product(% conversion) 1 2 3 4 5 4.4 27.7 31.4 8.2 28.0 23.8 30.8 15.0 8.7 21.3 20.2 33.2 30.3 5.6 10.5 23.2 26.1 3.4 36.0 11.2 12.8 30.3 5.3 30.6 14.5 o‐tolylboronic(B) 2 phenylboronic (A) m‐tolylboronic(B) 3 phenylboronic (A) p‐tolylboronic(B) Table 1: Reaction of boronic acid and gold nanocatalysts without polyaniline 4 o‐tolylboronic(A) m‐tolylboronic(B) 5 o‐tolylboronic(A) p‐tolylboronic(B) (1) Homocoupling of A, (2) Cross Coupling of A and B, (3) Homocouping of B, (4) Oxidation of A and (5) Oxidation of B The amount of poly-(m-aminophenol) is 5 mg Entry Starting material 1 phenylboronic (A) Products (% conversion) 4 5 28.3 1 18.7 37.4 2 3 6.3 9.1 18.7 39.4 26.4 6.5 8.9 Table 3: Reaction of boronic acid and gold nanocatalysts with poly-(m-aminoaniline) Entry Starting material Product (% conversion) o‐tolylboronic(B) 2 phenylboronic (A) 1 m‐tolylboronic(B) 3 phenylboronic (A) 10.3 32.6 50.3 2.7 o‐tolylboronic(A) 2 24.6 25.3 28.1 10.4 o‐tolylboronic(A) 3 15.8 42.6 20.0 10.9 4 5 2.3 55.2 phenylboronic (A) 10.6 8.5 1.6 28.9 50.3 phenylboronic (A) 13.0 13.6 4.7 21.9 46.8 17.5 11.4 1.4 49.9 19.8 26.0 19.2 1.3 50.2 3.4 p‐tolylboronic(B) 10.5 4 p‐tolylboronic(B) 3 15.0 m‐tolylboronic(B) 11.4 m‐tolylboronic(B) 5 2 20.1 o‐tolylboronic(B) 4.0 p‐tolylboronic(B) 4 phenylboronic (A) 1 4.4 o‐tolylboronic(A) m‐tolylboronic(B) (1) Homocoupling of A, (2) Cross Coupling of A and B, (3) Homocouping of B, (4) Oxidation of A and (5) Oxidation of B 5 o‐tolylboronic(A) p‐tolylboronic(B) For poly-(m-aminophenol) (Table 2) and poly-(maminoaniline) (Table 3), products were obtained by the effect not only from starting materials themselves but also from the stabilizer. Poly-(m-aminophenol) motivates reaction to oxidation more than coupling compared with ligandless catalysts (Table 1). Total amount of homocoupling products is decreasing, especially boronic acids with high steric effects. Similarly, boronic acids with high steric become more phenol in oxidation part. In the case of poly-(maminoaniline), this polyaniline gives more oxidation products while most coupling products are decreasing. The result shows that poly-(m-aminoaniline) can lead reaction selectively to oxidation. When increasing the amount of poly-(m-aminoaniline) to 40 mg, oxidation products are found as major product (99 percentage conversion). In the case of poly-(m-aminophenol) and poly-(m-aminoaniline), both have significant two (1) Homocoupling of A, (2) Cross Coupling of A and B, (3) Homocouping of B, (4) Oxidation of A and (5) Oxidation of B The amount of poly-(m-aminoaniline) is 5 mg Pure and Applied Chemistry International Conference 2014 (PACCON2014) 207 Figure 1 : TEM images of a) poly-(m-aminophenol), b) poly -(m-aminophenol) with gold, c) poly-(maminoaniline) and d) poly-(m-aminoaniline) with gold 4. Conclusions Gold nanocatalysts can be stabilized by polyaniline to prevent aggregation problem. Coupling products decreased when poly-(m-aminophenol) is used, and the reaction prefers oxidation when poly-(maminoaniline) is used as stabilizer. Acknowledgements We acknowledge PERCH-CIC and for Development of Pharmaceuticals from Bioresources and Its Management (NRU) financial support. References [1] Astruc, D.; Lu, F., Aranzaes, J. R., 2005, Angew. Chem, Int. Ed., 44, 7852. [2] Daniel, M. C.; Astruc, D., 2004, Chem. Rev, 104, 293. [3] Gonzalez-Arellano, C.; Abad, A.; Corma, A.; Garcia, H.; Iglesias, M. and Sanchez, F., 2007, Angew. Chem., Int. Ed., 46, 1536. [4]Corma, A.; Gonzalez-Arellano, C.; Iglesias, M. and Sanchez, F., Angew. Chem., Int. Ed. [5] Manea, F.; Houillon, F. B.; Pasquato, L. and Scrimin, P., 2004, Angew. Chem., Int. Ed. [6] Carrettin, S.; Guzman, J. and Corma, A., 2005, Angew. Chem., Int. Ed., 44, 2242. [7] Tsunoyama, H.; Sakurai, H.; Ichikuni, N.; Negishi, Y. and Tsukuda, T., 2004, Langmuir, 20, 11293 [8] Gonzalez-Arellano, C.; Corma, A.; Iglesias, M. and Sanchez, F., 2005, Chem. Commun., 1990. [9] Chairoenwimolkul, L. and Somsook, E., 2008, Tetrahedron Letters, 49, 7299-7302. [10] Li, W. G.; Jia, Q. X. and Wang, H. L., 2006, Polymer, 47, 23. Pure and Applied Chemistry International Conference 2014 (PACCON2014) 208 CRYSTAL STRUCTURE OF SILVER(I) CHLORIDE COMPLEX WITH N-ALLYLTHIOUREA AND TRIPHENYLPHOSPHINE Mareeya Hemman1*, Chaveng Pakawatchai1, Saowanit Saithong1, Jaursup Boonmark2 and Sujittra Youngme2 1Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand 2Department of Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand *E-Mail: [email protected], Tel. +66 83 1946463 Abstract: The complex of [Ag(Altu)(PPh3)2Cl]∙CH3CN was synthesized by the reaction of silver(I) chloride with N-allylthiourea (Altu) and triphenylphosphine (PPh3). The structure has been characterized by single crystal X-ray diffraction, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The complex crystallizes in Pī with cell parameters a = 11.0537(4) Å, b = 13.1661(5) Å, c = 14.6392(5) Å, α = 99.2140(10)°, β = 99.1030(10)°, γ = 92.5920(10)°, V = 2071.08(13) Å3 and Z = 2. The Ag(I) ion is four-coordinated by one Altu molecule, two PPh3 molecules and one chloride ion, forming a distorted tetrahedral geometry. 1. Introduction The coordination chemistry of silver(I) complexes with phosphorus and sulfur donor ligands has become of wide interest in recent years because of several potential; such as biological relevance of metal– sulfur interactions in the living systems and the potential applications of silver–phosphine complexes as antitumor/antibacterial agents [1–4]. Nallylthiourea is a substituted thiourea which is the sulfur donor ligands which can bind to a metal or a group metals via a variety of bonding modes. Furthermore, the reaction of inorganic silver(I) salts with organophosphorus, such as triphenylphosphine, lead to a design of different formation, depending on the nature of the ligand, stoichiometric ratio between the reactances and experimental conditions [5]. In this work, we report the synthesis and structural characterization of silver(I) complex containing Nallyltiourea and triphenylphosphine as ligands; [Ag(Altu)(PPh3)2Cl]·CH3CN. 2. Materials and Methods 2.1 Material and instruments All chemicals and solvents for synthesis were of reagent grade and used without purification. The complex was characterized by FT-IR spectrum (KBr disk, 4000–400 cm−1) recorded on a BX Perkin-Elmer FT-IR spectrophotometer, 1H NMR and 13C NMR were recorded on a Bruker FT-NMR Ultra Shield™ spectrometer, operating at a frequency of 300 MHz and using CDCl3 or DMSO as solvent with reference to an internal standard of tetramethylsilane (TMS). The melting point was determined with a capillary melting point apparatus. The crystal structure was studied by single crystal Xray diffraction using the Bruker D8 Quest diffractometer [6]. The structure was solved by direct methods and refined using SHELXTL NT (version 6.14) and WinGX (version 2013) crystallographic program [7-8]. 2.2 Preparation of [Ag(Altu)(PPh3)2Cl]·CH3CN Triphenylphosphine (0.26 g, 1.0 mmol) was first dissolved in 30 mL of acetonitrile. AgCl (0.07g, 0.50 mmol) was then added into the solution. The mixture was heated with stirring until a white precipitate was formed, and N-allylthiourea (0.06g, 0.50 mmol) was added. The reaction mixture was refluxed for 4 hours where upon the precipitate gradually disappeared. The resulting clear solution was filtered off and left to evaporate at room temperature. The colorless microcrystals were obtained after few days. The melting point of complex is 174-176°C. Main IR peaks (KBr disc)/cm−1: 3280(s), 3077(s), 1570(s), 1480(m), 1437(m), 1325(m), 1097(s), 1027(m), 752(s), 700(s), 667(m). 1H NMR (CDCl3, δ ppm): 8.30 s (-NH-), 7.39-7.22 m (HPh). 13C NMR data (CDCl3, δ ppm): 180.91s (C=S), 134.03-128.63 m (Cph). The structure was further confirmed by X-ray diffraction. 3. Results and Discussion 3.1 Infrared Spectroscopy The characteristic peaks of vibrational spectrum at 3077 and 1480 cm-1 are assigned to ν(=C-H) and ν(C=C) of phenyl rings respectively and the peaks at 700-752 cm-1 exhibit δ(C-H) out of plane of aromatic ring, indicating the presence of triphenylphosphine in the complex structure. The N-allylthiourea ligand contains –NH–C(=S)– group which may apply either the thione –NH–C(=S)– or thiol –N=C(–SH)– form. In this case, the ligand adopts the thione form which observed by the absence of the -SH band in the region ca. 2400-2600 cm-l [9], but there is the sharp band at 3280 cm-l, presenting ν(NH). In addition, the spectra at 1570 1325, 1027 and 667 cm-1 are attributed to ν(C-N) + δ (NH), ν(C-N) + δ(NH) + δ(C-H), ν(C-N) + ν(C=S) and ν(C=S) respectively, Pure and Applied Chemistry International Conference 2015 (PACCON2015) 209 suggesting that N-allylthiourea is coordinated to Ag(I) through S atom of thione group according to Singh et al. (2008) [10]. 3.2 1H NMR and 13C NMR Spectroscopy The 1H NMR spectrum of triphenylphosphine shows signals at 7.24 to 7.38 ppm due to equivalent ring protons (aromatic protons), while the complex shows there signals at 7.22-7.39 ppm. The complex shows signal due to N–H proton at 8.30 ppm, while free ligand N-allylthiourea shows a single resonance at 7.65 ppm. The downfield shifting from free ligand displays the ligand is coordinating to silver(I) via the thione group. The deshielding of the N–H proton is related to an increase of the π electron density in the C–N bond upon complexation [11-12]. The 13C NMR spectra supply more convincing information about the monodentate behaviour of thiourea moiety in the complex. The signals of the triphenylphosphine ring carbon (δ CPh) of the complex were observed in the region 128.63-134.03 ppm, and the free ligand shows the signals about 128.43-137.16 ppm. It shows the aromatic rings in the structure. Moreover, the important peak at 180.91 ppm is assigned the C=S signals appearing upfield from the free ligand (183.76 ppm). The upfield shift is attributed to lowering of C=S bond order upon coordination, indicating the presence of sulfur to metal bonds in the complex and a shift of N→C electron density producing partial double bond character in the C–N bond [12-13]. 1 H NMR and 13C NMR spectra support that the complex was synthesized to be the mixed ligand Ag(I) complex. 3.3 X-ray structural investigation The complex crystallizes in triclinic system space group Pī with the crystallographic data are shown in Table 1. The structure forms a distorted tetrahedral silver(I) center with two phosphorus atoms of triphenylphosphine molecules, one sulfur atom of Nallylthiourea molecule and one chloride ion. In addition, an acetronitrile solvent molecule is found in asymmetric unit. The structure is shown in Figure 1 and selected bond distances and angles are listed in Table 2. Distorted tetrahedral geometries are also found in similar silver(I) halide complexes which contain phosphine and thiourea ligands [14-15]. There are two notable hydrogen bonds. N(1)–H(1)...Cl(1) (3.265(3) Å) is the hydrogen bond between N(1)– H(1) of N-allylthiourea and chloride ion of the adjacent molecule, and another is N(2)–H(2)...S(1) (3.279(2) Å) formed between N(2)–H(2) of Nallylthiourea and sulfur atom of the adjoining sphere as shown in Figure 2. Furthermore, the adjacent molecules are connected together through N–H···Cl and N-H···S hydrogen bonds to form a onedimension chain structure running along a axis as shown in Figure 3. Table 1: Crystal data and structure refinements of [Ag(Altu)(PPh3)2Cl]∙CH3CN Crystals parameters Empirical formula Formula weight Crystal system Space group a (Å) b (Å) c (Å) α (°) β (°) γ (°) V (Å3) Z F(000) R indices [I > 2σ(I)] R indices (all data) Goodness-of-fit on F2 [Ag(Altu)(PPh3)2Cl]∙CH3CN C42H41AgClN3P2S 825.10 Triclinic Pī 11.0537(4) 13.1661(5) 14.6392(5) 99.214(1) 99.103(1) 92.592(1) 2071.08(13) 2 848 R1 = 0.0339, wR2 = 0.0678 R1 = 0.0522, wR2 = 0.0745 1.042 Table 2: Selected bond distances and angles of [Ag(Altu)(PPh3)2Cl]∙CH3CN Bond distances) (A๐) Ag1-S1 2.5885(8) Ag1-P1 2.4848(7) S1-C37 1.710(3) N1-C37 1.314(3) N2-C37 1.332(3) N2-C38 1.456(4) P1-C1 1.822(3) P1-C7 1.823(3) P1-C13 1.823(3) P2-C19 1.817(3) P2-C25 1.827(3) P2-C31 1.830(3) Bond angles (๐) P2-Ag1-P1 123.06(3) P1-Ag1-S1 110.53(3) P2-Ag1-S1 109.46(3) P1-Ag1-Cl1 103.82(3) P2-Ag1-Cl1 104.61(3) S1-Ag1-Cl1 103.16(3) Figure1. The [Ag(Altu)(PPh3)2Cl]∙CH3CN structure and hydrogen atoms are omitted for clarity. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 210 References Figure2. Hydrogen bonding [Ag(Altu)(PPh3)2Cl]∙CH3CN. interactions in Figure3. One-dimension hydrogen bonding interactions of [Ag(Altu)(PPh3)2Cl]∙CH3CN run along a axis. 4. Conclusions [1] Ahmad, S., Isab, A. A., Ali, S. and Al-Arfaj, A. R., 2006, Polyhedron, 25, 1633-1645. [2] Lobana, T. S., Sharma, R. and Butcher, R. J., 2008, Polyhedron, 27, 1375-1380. [3] Meijboom, R., Bowen, R. J., Berners-Price, S. J., 2009, Coord. Chem. Rev., 253, 325-342. [4] Nomiya, K. Yoshizawa, A., Tsukagoshi, K., Kasuga, N.C., Hirakawa, S. and Watanabe, J., 2004, J. Inorg. Biochem., 98, 46-60. [5] Ferrari, M. B., Bisceglie, F., Cavalli, E., Pelosi, G., Tarasconi, P. and Verdolino, V., 2007, Inorg. Chim. Acta., 360, 3233-3240. [6] Bruker, 2007, SMART, SAINT and SADABS, Bruker AXS Inc., Madison, Wisconsin, USA. [7] Sheldrick, G. M., 2008, Acta Cryst., A64, 112–122. [8] Farrugia, L. J., 2012, J. Appl. Cryst., 45, 849-854. [9] Bharti, A., Bharati, P., Bharty, M. K., Dani, R. K., Singh, S. and Singh, N. K., 2013, Polyhedron, 54, 131-139. [10] Singh, N. K., Singh, M., Tripathi, P., Srivastava, A. K. and Butcher, R. J., 2008, Polyhedron, 27, 375–382. [11] Isab, A. A., Ahmad, S., and Arab, M., 2002, Polyhedron, 21, 1267-1271. [12] Isab, A. A., Nawaz, S., Saleem, M., Altaf, M., Monim-ul-Mehboob, M., Ahmad, S. and Evans, H. S., 2010, Polyhedron, 29, 1251–1256. [13] Isab, A. A., Fettouhi, M., Ahmad, S. and Ouahab, L., 2003, Polyhedron, 22, 1349-1354. [14] Jantaramas, P., 2011, Silver(I) complexes with acetylthiourea and triphenylphosphine, Master's Thesis, Prince of Songkla University. [15] Lobana, T. S., Khanna, S., Sharma, R., Hundal, G., Sultana, R., Chaudhary, M., Butcher, R. J. and Castineiras, A., 2008, Cryst.Growth Des., 8, 12031212. The N-allylthiourea and triphenylphosphine react with AgCl to form complex of [Ag(Altu)(PPh3)2Cl]∙CH3CN. Results from infrared spectroscopy and 1H and 13C NMR spectroscopy support the structure is the mixed ligands complex. The crystal structure of a novel mononuclear silver(I) complex is also presented, in which the thione and phosphine ligands coordinate through the sulfur and phosphorus atoms repectively, suggesting distorted tetrahedral geometry around silver ion. In addition, hydrogen bonding interactions are found in crystal packing which link adjacent molecules, forming onedimention down a axis. Acknowledgements The authors thank the financial supports from the Faculty of Science for the Research Assistant scholarship to Miss Mareeya Hemman, the Department of Chemistry and Graduate School, Prince of Songkla University. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 211 SYNTHESIS AND CHARACTERIZATION OF CADMIUM(II) COMPLEX WITH 4,4′-BIPYRIDINE AND CINNAMIC ACID Sirinart Chooset1, Anob Kantacha2, Arunpatcha Nimthong3, and Sumpun Wongnawa1* 1Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand 2Department 3Department of Chemistry, Faculty of Science, Thaksin University, Patthalung, 93110, Thailand of Chemistry, Youngstown State University, One University Plaza, Youngstown, OH 44555, USA *E-mail: [email protected], Tel. +66 74 288443, Fax. +66 74558841 Abstract: [Cd3(4,4′-bipyridine)2(cinnamate)6(H2O)2]n was synthesized using hydrothermal method with Cd(CH3COO)2⋅2H2O , 4,4′-bipyridine, and cinnamic acid as starting materials. The obtained complex was investigated by Fourier-transformed infrared spectroscopy (FT-IR), single crystal x-ray diffraction (SCXRD), and thermogravimetric analysis (TGA). Single crystal x-ray diffraction study revealed that the complex crystallized in triclinic space group P ī. The octahedral geometry Cd(1) was coordinated by four oxygen atoms from cinnamate ligand and two oxygen atoms from water molecules, while Cd(2) and Cd(3) were coordinated by five oxygen atoms from cinnamate ligand in the equatorial position and the axial position by two nitrogen atoms from 4,4′-bipyridine ligand, forming a pentagonal bipyramidal geometry. 1. Introduction Metal–organic coordination polymer is of great current interest due to their potential applications as functional materials such as catalysis, gas storage, ionexchange magnetism and molecular sensing [1]. Coordination chemistry of cadmium with carboxylic acid ligands is interesting because of its possible applications in catalysis, biologically active compounds, molecular electrochemistry, etc [2]. Cinnamic acid is a carboxylate ligand which is an important class of ligands in the formation of coordination polymers. Cinnamate ligand is capable of binding to a metal in a monodentate, bidentate or bridging mode lead to mono- and polynuclear molecular and polymeric structures [3]. 4,4′Bipyridine (4,4′-bipy) is a bidentate bridging ligand with coordination sites at two ends of the rigid molecule, which has been widely used in crystal engineering of coordination polymers [4]. In this work, we report the synthesis and structural characterization of the cadmium(II) complex with 4,4′-bipyridine and cinnamic acid as ligands. mL Teflon-lined Parr autoclave at 120 °C for 3 days. The resulting crystals were isolated by filtration, washed with water, and dried in air. Crystals of this complex were obtained and characterized by SCXRD, FT-IR, and TGA analysis. The Cd(II) complex was found to be air stable and insoluble in organic solvents. Determination of cell parameters and data collection was carried out with APEX2, cell refinement with SAINT, and data reduction with SAINT and SHELXTL. SHELXS97 was used in solving the structure, while SHELXL2013 and SHELXLE were used in the structure refining. All the graphic manipulations were carried out with MERCURY. IR spectra were obtained using KBr pellet on Perkin-Elmer Spectrum One Fouriertransformed infrared spectrophotometer between 4000 – 400 cm-1. Thermogravimetric analyses (TGA) were carried out on a Perkin Elmer TGA 7 over the temperature range of 50 – 1000 ◦C and at a heating rate of 10 ◦C/ min. Figure 1. The infrared spectra of [Cd3(4,4′-bipyridine)2 (cinnamate)6(H2O)2]n (red line), 4,4′-bipyridine(blue line) and cinnamic acid (green line). 2. Materials and Methods Cd(CH3COO)2⋅2H2O, 4,4′-bipyridine, and cinnamic acid were purchased from commercial sources and used as received. [Cd3(4,4′-bipyridine)2(cinnamate)6 (H2O)2]n was prepared by a mixture of 1 mmol Cd(CH3COO)2⋅2H2O, 2 mmol cinnamic acid, 1 mmol 4,4’-bipyridine, and 20 mL H2O was heated in a 23 Pure and Applied Chemistry International Conference 2015 (PACCON2015) 212 Table 1. Selected bond distances and angles of [Cd3(4,4′-bipyridine)2(cinnamate)6(H2O)2]n Bond angles (๐) Bond distances (Å) Cd1—O5 2.2942 (18) N2—Cd2—N1 174.13 (4) Cd1—O4 2.3590 (11) N2—Cd2—O2 98.22 (5) Cd1—O7 2.2879 (13) N1—Cd2—O2 87.42 (4) Cd2—N2 2.2683 (13) N2—Cd2—O1 96.42 (5) Cd2—N1 2.3082 (12) N1—Cd2—O1 85.48 (5) Cd2—O2 2.3214 (11) O2—Cd2—O1 54.95 (4) Cd2—O3i 2.3554 (10) O7—Cd1—O5 87.34 (6) Cd2—O1 2.4222 (12) O7—Cd1—O4 89.36 (4) Cd2—O4 2.4336 (12) O5—Cd1—O4 85.91 (5) Cd2—O3 2.5016 (11) Figure 2. Structure of [Cd3(4,4′-bipyridine)2 (cinnamate)6(H2O)2]n (H atoms and the disordered C atoms omitted for clarity). Figure 3. Crystal packing of [Cd3(4,4′-bipyridine)2 (cinnamate)6(H2O)2]n viewed along a axis (H atoms and the disordered C atoms omitted for clarity). Figure 4. The TGA curve of [Cd3(4,4′-bipyridine)2 (cinnamate)6(H2O)2]n 3. Results and Discussion Infrared Spectroscopy The preliminary identification of [Cd3(4,4′bipyridine)2(cinnamate)6(H2O)2]n complex was based on the IR spectra in Figure 1. The bands at 3438 and 1611 cm-1 were assigned to the symmetric OH stretching and the OH bending vibration of water molecules, respectively. The unsaturated ν(=CH) stretching vibrations appeared at 3114 and 3076 cm−1. Three C=O stretches of this complex appeared at (1594, 1442) , (1552, 1394), and (1574, 1354) cm−1 which were assigned to νas (COO) and νs(COO) vibrations of three types of cinnamate ligands. The C=O stretching vibrations of cinnamate ligand in the complex compared with the same mode in free cinnamatic acid molecule show a significant blue-shift due to the coordination interactions. The ΔνCOO = νas(COO) − νsym(COO) are 152, 202 and 220 cm−1 in the complex corresponding to the presence of bidentate, monodentate, and bridging carboxylate group, respectively, of cinnamic acid [5-7]. The C–N stretching vibration was approximately 1243 cm-1, indicating that the bpy group was included in the complex. The FT-IR information is consistent with the results from the X-ray single crystal analysis of the complex. Thermogravimetric analysis Thermogravimetric analysis (TGA) of 2-D structure of a cadmium coordination polymer is shown in Figure 4. The first weight loss of 3.12 % in the temperature range of 100 – 130 oC which was assigned to the release of two molecules of H2O (compared to the calculated value of 2.27%). The second weight loss of 56.88 % occurred in the temperature range of 140 – 380 oC corresponding to five cinnamate ligands and a 4,4′-bipyridine ligand, compared to the calculated 54.41 %. The third weight loss was 19.42% in the temperature range of 400 – 680 oC corresponding to one each of cinnamate and 4,4′-bipyridine ligand, compared with the calculated value of 18.34 %. On further heating the residue started to decompose completely to CdO [1]. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 213 X-ray structural investigation The X-ray crystallography revealed that the complex crystallized in triclinic system space group P ī with cell parameters a = 10.8357 (15), b = 11.6010 (16), c = 13.9036 (19) Å, α =74.388 (2) °, β = 80.131 (2) °, γ = 88.310 (2) °, V = 1658.1 (4) Å3 and Z = 1. The size of the colorless crystal was 0.20 × 0.09 × 0.05 mm. The selected bond lengths and bond angles are given in Table 1. Molecular structure of the title complex is shown in Figure 2. The Cd(1) is coordinated by four oxygen atoms from four cinnamate units and two oxygen atoms from two water molecules forming a distorted octahedral geometry. The carboxylate group of cinnamate containing O5 and O5a is monodentate ligand and the other carboxylate group containing O4 and O4a is bidentate and bridging ligand. Cd(2) and Cd(3) are coordinated by five oxygen atoms from carboxylic of three cinnamic acid around Cd(2) and Cd(3). All five oxygen atoms, O(1), O(2) O(3), O(3i) and O(4), are located at the equatorial plane while N(1) and N(2) occupy the axial position with bond angle N(1)-Cd(2)N(2) 174.13(4)o to give a pentagonal bipyramidal geometry [8]. Furthermore, in the complex, each cinnamate ligand adopts two coordination modes, the O,O-bidentate chelate mode and the tridentate bridging mode. The crystal packing of [Cd3(4,4′bipyridine)2(cinnamate)6(H2O)2]n is shown in Figure 3. References [1] Seung, P. J., Jung, I. P., Soo, H. K., Tae, G. L., Jin, Y. N., Cheal, K., Youngmee, K. and Sung, J. K., 2012, Polyhedron., 33, 194–202. [2] Tang, S. P. 2008., Chinese journal of inorganic chemistry., 24, 977-980. [3] Han, K., Sun, H. L., Soo, H. K., Young, M. L., Byeong, K. P., Eun, Y. L., Yu, J. L., Cheal, K., Sung, J. K. and Youngmee, K., 2008, Polyhedron., 27,3484–3492. [4] Rüdiger, W. S., Richard, G., Bodo, Z., and Iris, M.O., 2011, Polymers., 3, 1458-1474. [5] Kalinowska, M., S´wisłocka, R., and Lewandowski, W. 2011, Journal of Molecular Structure., 993, 404–409. [6] Raj, P. S., Anju, S., Paloth, V., Julia, J. and Valeria, F., 2012, Inorganic Chemistry Communications., 20, 209–213. [7] Glen, B. D., Maria, F., Peter, C. J., Stuart, G. L. and Winnie, W. L., 2009., Journal for Inorganic and General Chemistry., 635, 833-839. [8] Xian,W.W., Jing, Z. C. and Jian, H. L., 2007, A Journal of Chemical Sciences., 62, 1139 – 1142. 4. Conclusions The complex [Cd3(4,4′-bipyridine)2(cinnamate)6 (H2O)2]n was prepared via the reaction of Cd(II)salt , 4,4′-bipyridine, and cinnamic acid using hydrothermal method. The complex structure was obtained from single crystal x-ray diffraction technique combined with spectroscopic and thermogravimetric techniques. Within the crystal structure, Cd(1) coordinated to oxygen atoms from cinnamic acid and water molecule to form an octahedral geometry whereas Cd(2) and Cd(3) coordinated to oxygen atoms from cinnamic acid and nitrogen atoms from 4,4′-bipyridine forming a pentagonal bipyramidal geometry. The 2-D structure was formed via the bridging 4,4′-bipyridine and cinnamate ligand. Acknowledgements This work was supported by the Songklanagarind Scholarship for Graduate Studies from Prince of Songkla University. We would like to thank Dr. Matthias Zeller for valuable suggestions and assistance with X-ray structure determination and use of structure refinement programs. We would like to thank the Department of Chemistry and the Graduate School, Prince of Songkla University. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 214 SYNTHESIS OF CALCIUM SILICATE FROM SHELL OF POMACEA CANALICULATA AND RICE HUSK ASH BY MECHANOCHEMICAL METHOD Phatthareeya Suriya1, Ratchadaporn Puntharod1,2* 1Department 2Nanoscience of Chemistry, Faculty of Science, Mae jo University Chiang Mai, 50290, Thailand and Nanotechnology Laboratory, Mae Jo University, Chiang Mai, 50290, Thailand *E-mail: [email protected], Tel. +66 5387 3530, Fax. +66 5387 3548 Abstract:Calcium silicate was synthesized using silica from rice husk ash and calcium oxide from shell of snail namely Pomacea canaliculata calcined at 800 oC for 2 hours. The rice husk ash and calcined shell in molar ratio of 1:1 were ground by alumina ball with high speed milling. The solid powder was calcined at 800 and 1000 oC for 2 hours. The formation of calcium silicate was firstly investigated by Fourier transform infrared spectroscopy. The temperature for calcination could affect the occurring of calcium silicate with appearance the band of Ca−O−Si at 935 cm-1. Calcium silicate was starting occurred while mixed oxide was ground for 1 hour and calcined at 1000 oC. The phase of calcium silicate was confirmed by X-ray diffractometry. 1. Introduction Calcium silicate or wollastonite is mineral from nature. It has been applied in industry such as ceramic, plastics, construction materials [1] and a substitute for asbestos [2] including biodiesel reaction as catalyst in transesterification reaction [3]. Mechanochemical method is a kind of solid state reaction. This method in high energy milling has been found widely spread applications for the synthesis of many solid inorganic compounds[4].Anew approach to the mechanochemical synthesis of inorganic compounds is based on the mechanical activation of mixtures of solid acids, bases and compounds with reactive hydroxyl groups or coordinated water. This process involved high-energy collisions of the grinding media and reactant, resulting in chemical reactions called mechanochemistry without any external heating. The main advantage of the mechanochemical method is carried out at room temperature instead of high temperature. The high speed milling process involves repeated mixing, deformation, comminuting, welding and rewelding of the reactant powder particles in a closed jar of a planetary ball mill. Also this method is environmental friendly and free of organic-inorganic solvents [5,6]. The purposed of this work was to synthesize of calcium silicate from shell of snail namely Pomacea canaliculata and rice husk ash by mechanochemical method with high speed milling and to study the temperature of calcination for occurrence of calcium silicate. 2.1 Materials The raw shells of snail namely Pomacea canaliculata and rice husk were collected from rice field in Chiangmai province. The shells were washed with tap water, dried at room temperature, and manually crushed by a porcelain mortar. The small pieces of solids were calcined in muffle furnace at 800 ο C for 2 hr. Rice husk ash was prepared by burned rice husk in biomass gasifier stove. 2.2 Experimental The staring raw materials were calcium oxide and rice husk ash. The mixtures of these raw materials equvivalent in molar ratio of 1:1were ground by alumina ball with high speed milling at 380 rpm (Foshan Shenglong Cermaics Equipment).The mixed power-to-ball weight ratio was 1:4. The milling time was varied in range of 1, 2, and 3 hr. The solid powders werecalcined at 800 and 1000 οC for 2 hr to remove carbonate. 2.3 Characterization Fourier transform infrared spectra were recorded on a spectrometer (Perkin Elmer). The solid sample was mixed with the single crystal potassium bromide to obtain pellet. X-ray diffraction was taken and analyzed using an X-ray analyzer (Bruker). Scanning2θwasmeasured from 10-90ο. The peak positions were consistent with those of the international center for diffraction data standards to identify the crystalline phases. Scanning Electron Microscope ( Jeol) was used to observe microstructures. The samples were mounted on a stub using a carbon paste and were sputter-coated with gold to improve electrical conductivity. The magnification of 10,000× was used. 2. Materials and Methods Pure and Applied Chemistry International Conference 2015 (PACCON2015) 215 471 805 (b) 1429 3641 816 710 1104 (a) 4000 3500 3000 2500 2000 Wavenumber (cm-1) 1500 1000 500 Figure 1. FTIR spectra of (a)CaO from shell of snail namely Pomacea canaliculata calcined at 800οC for 2 hr and (b)SiO2 from rice husk ash. 516 1470 (c) band at 1429, 816 and 471 were assigned to CO32- of shell of snail [7].The broad band at 1104 cm-1of the rice husk ash was indicated the –OH vibration of surface hydroxyl groups. The bands at 805 and 471 cm-1were assigned to O−Si−O stretching and bending, respectively [8]. Figure 2 was the FTIR result of mixture between CaO and SiO2 at milling time of1,2 and 3 hr with calcined at 800 oC for 2 hr. The band of carbonate still appeared. It could not be removed completely while the solid product was calcined at 800 °C. The formation of Ca−O−Si of calcium silicate was disappeared. The result suggested that those conditions were not appropriate to synthesize calcium silicate. Figure 3 was the FTIR result of mixture between CaO and SiO2 at the milling time of1,2 and3 hr with calcined at 1000 oC for 2 hr. The band of Ca−O−Si of calcium silicate was appeared at 923-926 cm-1, while the band of CO32-was disappeared [9]. The calcination at 1000 oC was suitable temperature to synthesize calcium silicate. 1001 923 (b) CaSiO3 518 1469 5000 4000 517 Arbitary unit 999 926 (d) 1000 924 1469 (a) 4000 3500 3000 2500 2000 Wavenumber (cm-1) 1500 1000 500 Figure 2. FTIR spectra of mixture between CaO and SiO2 at milling time of(a) 1, (b) 2,and (c) 3 hr and calcined 800 °C for 2 hr. 517 461 2000 (c) 1000 (b) 0 (a) 0 20 40 60 80 100 2θ Figure 4. XRD pattern (a) wollastonite-1A (JCPDS No. 00-019-0249) and mixture between CaO and SiO2 at milling time of (b) 1, (c) 2, and (d) 3 hr and calcined 1000 °C for 2 hr. 432 717 566 (b) 997 923 517 455 (a) 717 1096 990 938 1070 1009 935 718 796 646 566 (c) 3000 4000 3500 3000 2500 2000 Wavenumber (cm-1) 1500 1000 500 Figure 3. FTIR spectra of mixture between CaO and SiO2 at milling time of (a) 1, (b) 2, and (c) 3 hr and calcined 1000 °C for 2 hr. 3. Resultsand Discussion The FTIR spectra of the silica from rice husk ash and calcium oxide from shell of snail namely Pomacea canaliculata calcined at 800 oC for 2 hr were shown in Figure 1.The band at 3641 cm-1was assigned to the Ca−O bonding of Ca(OH)2. The dominant peak around 2400 cm-1 was assigned to CO2 in atmosphere. The Figure 5. SEM micrograph of mixture between CaO and SiO2 at milling time of 1hr and calcined at 1000 o C for 2 hr. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 216 of calcium silicate was confirmed by XRD. The milling time and calcined temperature were influence the formation of calcium silicate, morphology and size of particle. The mechanochemical method with high speed milling is high potential tool and solvent free synthesis. Acknowledgements This research was financial supported by National Research Thailand. References Figure 6. SEM micrograph of mixture between CaO and SiO2 at milling time of 2 hr and calcined at 1000 o C for 2 hr. [1] Tangboriboon, N.,Khongnakhon, T.,Kittikul, S. Kunanuruksapong, and Sirivat, R.A., 2011,J. Sol-Gel Sci. Technol., 58, 33-41. [2] Demidenko, N.I., and Tel'nova, G.B., 2004, Glass Ceram., 61, 183-186. [3] Hsin, T., Chen, S., Guo, E., Tsai, C., Pruski, M., and Lin, V.S.Y., 2010, Top. Catal., 53, 746-754. [4] Billik, P. andCaplovicova, M., 2009, Powder Technol., 191, 235-239. [5] Zhou, C.F.,Du, X.S.,Liu, Z.,Ringer, S.P.,and Mai, Y.W., 2009, Synth. Met., 159, 1302-1307. [6] Huot, J., Ravnsbaek, D.B., Zhang, J., Cuevas, F., Latroche, M., and Jensen, T.R., 2013, Prog. Mater. Sci., 58, 30-72. [7] Engin, B., Demirtas, H., and Eken, M., 2006, Radiat. Phys. Chem., 75, 268-277. [8] Chandrasekhar, S., and Pramada, P.N., 2006, Adsorption, 12, 27-43. [9] Meiszterics, A., Rosta, L., Peterlik, H., Rohonczy, J., Kubuki, S., Henits, P., and Sinkó, K., 2010, J. Phys. Chem. A, 114, 10403-10411. Figure 7. SEM micrograph of mixture between CaO and SiO2 at milling time of 3 hr and calcined at 1000 o C for 2 hr. Calcium silicate was starting occurred while mixed oxide was ground for 1 hrand calcined at 1000 oC corresponded with FTIR results. The crystallinity of calcium silicate was increased as milling time increased. The phase of product was wollastonite-1A (JCPDS No. 00-019-0249) in Figure 4. The SEM micrographs of mixture between CaO and SiO2 at milling time of 1, 2 and 3 hr and calcined at 1000 oC for 2 hr were shown in Fig 5, 6, and 7, respectively. The size of particle was smaller as the milling time increased. The average size was less than 1 µm with irregular shape. This observation shows the influence of milling time on the morphology and the size of the particles. The longer milling time could provide the smaller particle size. 4. Conclusions Calcium silicate was successfully synthesized by mechanochemical method with calcination at 1000 οC using shell of Pomacea canalicalata and rice husk ash as starting materials. The temperature for calcination could affect the occurring of calcium silicate with appearance the band of Ca−O−Si by FTIR. The phase Pure and Applied Chemistry International Conference 2015 (PACCON2015) 217 EQUILIBRIUM EXTRACTION OF URANIUM AND THORIUM MIXTURES IN 4 M HNO3 WITH 5 AND 10% TBP/KEROSENE Uthaiwan Injarean1, Pipat Pichestapong1*, Yoreeta Marnchareon2, Sarin Cheephat2, Nattawadee Wisitruangsakul2, Boonnak Sukhummek2 1 Research and Development Division, Thailand Institute of Nuclear Technology, Bangkok 10900, Thailand of Chemistry, Faculty of Science, King Mongkut’s University of Technology Thonburi, Thung Khru, Bangkok 10140, Thailand 2 Department * E-mail: [email protected], Tel. +66 2562 0120, Fax. +66 2562 0120 Abstract: Solvent extraction technique has been used extensively for the separation and purification of uranium and thorium from other associated elements in the nuclear materials processing. In this work, the equilibrium extraction of uranium and thorium from 4 M HNO3 with 5 and 10% tributyl phosphate (TBP) in kerosene was investigated. The distribution coefficients of each element were studied at various concentrations of the individual solution and of the mixed solution. The element concentration was determined by ICP-AES. The distribution coefficients of both uranium and thorium were found to be varied with their concentration and the distribution coefficient of uranium is much higher than that of thorium. The extraction efficiency increased with higher TBP concentration but decreased with the increasing feed concentration. The uranium-thorium separation factor in the mixed solution was seen to depend on the mixture concentration and 10% TBP/kerosene extractant provided higher uraniumthorium separation factor than 5% TBP/kerosene. These equilibrium data are further developed according to the McCabe-Thiele approach to simulate the multistage counter-current extraction and separation of uranium and thorium mixtures. 1. Introduction Uranium fuel used in nuclear power plants is normally extracted from uranium ores with relatively high uranium content. However, some ores such as monazite, phosphate rock, and titanium ore, which contain a small amount of uranium, can be reserved for uranium mining. In the South of Thailand, monazite ore, found in the tailings of tin mines, contains about 0.24-0.79% of uranium, 4.5-10.6% of thorium and other rare earth elements in the form of phosphate compounds [1]. This monazite can be chemically processed to extract and separate nuclear elements from other components. In the alkaline process, monazite is usually digested with 50% NaOH at about 140 °C to convert phosphate compounds to hydroxides which later are dissolved by HCl and selectively precipitated at pH 4.5 to separate uranium and thorium from other rare earth elements. Mixed uranium and thorium cake is then dissolved into a nitrate solution. Solvent extraction process with a proper extractant is widely used to separate uranium from thorium as well as to purify each element. Separation and purification of uranium using tributyl phosphate (TBP) process has been employed in several countries. Other processes using organophosphoric compounds such as alkyl phosphine oxide and phosphonate, phosphinate, and ketones or ethers were also reported. However, the TBP process was seen to have more advantages and was widely chosen [2-6]. The extraction of uranium nitrate and thorium nitrate by TBP is shown in the following reactions: UO22+ + 2 NO3− + 2 TBP = UO2(NO3)2 · 2 TBP Th4+ + 4 NO3− + 4 TBP = Th(NO3)4 · 4 TBP The typical separation and purification processes usually include the scrubbing step using appropriate solution to scrub some impurities, which may be extracted into the extractant along with the uranium, to ensure the purity of uranium before being stripped and precipitated. In this work, the equilibrium extraction of uranium and thorium in 4 M HNO3 as individual and mixed solutions has been investigated using 5 and 10% TBP/kerosene extractants. Batch simulation of the multistage extraction and separation of uranium in the mixture with both extractants were also studied. 2. Materials and Methods Feed solutions were prepared by dissolving and uranium(VI) nitrate (UO2(NO3)2•6H2O) thorium(IV) nitrate (Th(NO3)4•5H2O), obtained from Merck, in 4 M HNO3. TBP used in the extraction solvent was from Fluka and kerosene was from PTT. The solutions of 5 and 10% TBP in kerosene were used as the extractants. Equilibrium extraction was carried out using separatory funnels on a shaker at room temperature (32 ± 2 °C) with a speed of 200 rpm and contact time of 10 min to ensure an equilibrium state [2-3]. Equilibrium distribution coefficient (D) of U and Th between aqueous feed and organic extractant at various feed concentrations was determined as the ratio of element concentration in organic phase to element concentration in aqueous phase. The concentrations of elements in the samples were determined using ICP-AES spectrometer (Optima 5300 DV, Perkin Elmer). Pure and Applied Chemistry International Conference 2015 (PACCON2015) 218 2.1 Equilibrium extraction of individual solution The initial feed was prepared at high uranium or thorium concentration and other feeds were prepared by dilution of this initial feed with 4 M HNO3. The concentrations of uranium feed and thorium feed employed in this work were in the range of 500– 30,000 mg/L. 2.2 Equilibrium extraction of mixture solution The feed of uranium and thorium mixtures were prepared by mixing uranium feed and thorium feed. Two series of mixture solutions were prepared. The first series has a constant concentration ratio of uranium to thorium at 1:1 and the total concentration was in the range of 500–25,000 mg/L. The other series has a fixed concentration at 15,000 mg/L and the concentration ratio of uranium to thorium was varied. 2.3 Batch simulation of multistage extraction The extraction of uranium from the mixture was carried out in batchwise laboratory scale to simulate the multistage counter-current extraction as shown in Figure 1. The left figure illustrates the extraction pattern that was followed for batch simulation of the 3stage continuous counter-current extraction process shown on the right figure. The procedure consists of repeated introductions of fresh feed solution (F) and fresh extractant (S) into a series of batch extractions, plus withdrawal of extract (E) and raffinate (R) phases. Each circle represents a batch extraction in a separatory funnel. After a number of extraction cycles, the system should approached steady state and the liquids in the funnels resemble the streams that would exist in an actual continuous countercurrent extraction [7-8]. The cycles of batch extraction were carried out to simulate 2, 3 and 4 stages in counter-current extraction using feed to extractant ratio of 1:1. shown in Figure 3 and Table 2. It is seen that extraction of both uranium and thorium with 10% TBP/kerosene is higher than that with 5% TBP/kerosene and their distribution coefficients increase with decreasing concentrations which is similar to other reports [5-6]. However, the distribution coefficient of uranium, 1.12–7.50 with 5% TBP/kerosene and 4.11–18.00 with 10% TBP/kerosene, is much higher than that of thorium, 0.05–0.20 with 5% TBP/kerosene and 0.20–1.05 with 10% TBP/kerosene. It is noted that distribution coefficients of uranium and thorium increases about 4 times as the concentration of TBP increases from 5 to 10%. This distribution coefficient can be used to calculate the extraction efficiency of the solvent and to analyze the number of extractions required for the desired process efficiency. Table 1: Distribution coefficients of uranium in the equilibrium extraction with 5 and 10% TBP/kerosene U conc. (mg/L) 29933 24180 20947 14633 11177 7992 3482 1540 852 596 Distribution coeff., DU 5% TBP 10% TBP 1.12 4.11 1.67 5.28 2.02 6.96 1.97 6.79 2.38 9.11 3.29 9.81 4.04 11.90 3.39 8.36 6.93 16.53 7.50 18.00 Figure 2. Equilibrium distribution of uranium in 4 M HNO3 and 5 and 10% TBP/Kerosene Figure 1. Batch simulation of 3-stage continuous counter-current extraction 3. Results and Discussion 3.1 Equilibrium extraction of individual solution The feed compositions and their equilibrium distribution of uranium are shown in Table 1 and their equilibrium concentrations are plotted in Figure 2. The similar equilibrium extraction data for thorium are also Figure 3. Equilibrium distribution of thorium in 4 M HNO3 and 5 and 10% TBP/Kerosene Pure and Applied Chemistry International Conference 2015 (PACCON2015) 219 Table 2: Distribution coefficients of thorium in the equilibrium extraction with 5 and 10% TBP/kerosene Distribution coeff., DTh 5% TBP 10% TBP Th conc. (mg/L) 25633 18953 16037 12790 9516 6336 3074 1513 888 571 0.09 0.13 0.10 0.20 0.06 0.13 0.17 0.16 0.12 0.05 0.24 0.20 0.29 0.25 0.37 0.52 0.58 1.05 0.77 0.27 3.2 Equilibrium extraction of mixture solution The mixture compositions and the separation factor of uranium and thorium (SFU/Th) are shown in Table 3 and 4 and their equilibrium concentrations are plotted in Figure 4 and 5. The uranium/thorium separation factor was determined from the distribution coefficient of uranium divided by that of thorium. The separation factor from first extraction series with constant 1:1 mixing ratio (Table 3) indicates that 10% TBP/kerosene extractant provides the separation factor, 4.11–18.00, higher than 5% TBP/kerosene, 1.12–7.50. The larger separation between 10% TBP/kerosene equilibrium lines of Th and U in Figure 4 also supports this data. However, the separation factors from the second extraction series with various mixing ratios (Table 4) show a different trend. The equilibrium extraction with 5% TBP/kerosene has separation factors of 19.5–67.7 corresponding to the average of 41.4 and the extraction with 10% TBP/kerosene has separation factors of 23.9–54.9 corresponding to the average of 31.7. This is hardly determined from Figure 5 as the distances between each pair of equilibrium lines are closely similar. It is quite obvious that the separation of uranium and thorium with TBP process can be affected by many factors such as the concentration of TBP, the concentration of feed and the concentration ratio between U and Th in the feed. There are also related factors involved in this separation process which are the recovery of uranium and the purity of uranium product. Table 3: Separation factors of uranium- thorium in the equilibrium extraction of feed with uranium and thorium mixture at constant 1:1 ratio U conc. (mg/L) Th conc. (mg/L) 9021 7755 6054 4588 3019 1436 761 444 297 151 8995 7755 6054 4592 3003 1484 751 444 295 151 Separation factor, SFU/Th 5% TBP 10% TBP 1.12 4.11 1.67 5.28 2.02 6.96 1.97 6.79 2.38 9.11 3.29 9.81 4.04 11.90 3.39 8.36 6.93 16.53 7.50 18.00 Table 4: Separation factors of uranium-thorium in the equilibrium extraction of feed with uranium and thorium mixture at various ratios U conc. (mg/L) Th conc. (mg/L) 13710 11850 10550 9148 7789 5917 4579 3087 1587 1541 2843 4445 5894 7345 9026 10270 11570 12620 Separation factor, SFU/Th 5% TBP 10% TBP 19.5 54.9 50.9 34.7 20.4 24.6 63.4 25.5 44.6 25.0 67.7 28.9 28.5 23.9 27.2 30.4 50.7 37.3 Figure 4. Equilibrium distribution of uranium and thorium mixtures at constant 1:1 ratio Figure 5. Equilibrium distribution of uranium and thorium mixtures at total constant concentration 3.3 Batch simulation of multistage extraction To evaluate U recovery and purity, a feed mixture of uranium and thorium, each with the concentration of 15,000 mg/L, was used for batch simulation in multistage extraction of uranium with 5 and 10% TBP/kerosene solvent. Based on the feed mixture, the initial purity of uranium is 50%. A suitable number of stages required for this separation process was predicted using McCabe-Thiele approach [7] with their equlibrium distribution curves. The purity and the recovery of uranium after simulation of 2, 3 and 4 stages counter-current extraction with feed to extractant ratio at 1:1 were shown in Figure 6 and 7 for the extraction with 5 and 10% TBP/kerosene, respectively. It was found that the recovery of uranium Pure and Applied Chemistry International Conference 2015 (PACCON2015) 220 increased with an increasing number of extraction stages as the uranium recovery with 5% TBP/kerosene extractant in 2, 3 and 4 extraction stages were 80.52, 90.79 and 96.74%, respectively while the purity of recovered uranium were around 94%. The extraction with 10% TBP/kerosene revealed higher uranium recovery at 97.91–99.85%, but the purity of recovered uranium were lower at 88%. The selection of extractant for the separation of uranium and thorium then also relies on both recovery and purity factors. In case of the 5% TBP/kerosene extractant, the U recovery curve indicates that recovery of uranium can be improved by increasing number of extraction stage. Also, in a practical process, a scrubbing step with proper solution or a re-extraction step can be used to achieve higher uranium purity. Figure 6. Uranium recovery and its purity obtained from multistage extraction with 5%TBP/kerosene 5% TBP/kerosene. Separation of U and Th with the TBP process was shown to be affected by many factors such as concentrations of TBP, concentrations of the feed and concentration ratios between U and Th in the feed. Batch simulation of multistage extraction of uranium in the mixture revealed that the recovery of uranium increased with number of extraction stage and higher TBP concentrations. However, the purity of extracted uranium decreased as its recovery increased. References [1] Rare Earth Research and Development Center, Office of Atomic Energy for Peace, 1996. [2] Stas, J., Dahdouh, A. and Shlewit, H., 2005, Periodica Polytechnica Ser. Chem. Eng., 49. [3] Kraikaew, J and Srinuttrakul, W. , 2006, Journal of the Nuclear Society of Thailand, 7. [4] Schulz, W.W., Navratil, J.D. and Bess, T. 1987, Science and Technology of Tributyl Phosphate, Volume II, CRC Press, Florida. [5] Ashbrook, A.W. and Lakshmanan, V. I., 1986, Uranium Purification, Eldorado Nuclear Ltd., Canada. [6] Huang, L., Zhuang, H., Niu Y. and Zhou, M., 1996, Technical Improvement of Uranium Purification, The International Conference on Uranium Extraction Conf. Proc., Beijing, China. [7] Treybal, R.E., 1963, Liquid Extraction, 2nd ed., McGraw Hill, New York. [8] Thornton, J.D., 1992, Science and Practice of LiquidLiquid Extraction, Vol. 1, Oxford University Press, New York. Figure 7. Uranium recovery and its purity obtained from multistage extraction with 10%TBP/kerosene 4. Conclusions The equilibrium extraction of uranium and thorium in 4 M HNO3 as individual and mixed solutions has been studied using 5 and 10% TBP/kerosene extractants. The distribution coefficients of each element were determined at various concentrations of the individual solution and of the mixed solution. The distribution coefficients of both uranium and thorium were found to be decreased with increasing concentrations and the distribution coefficient of uranium is much higher than that of thorium. 10% TBP/kerosene provided higher extraction capacity than Pure and Applied Chemistry International Conference 2015 (PACCON2015) 221 PREPARATION OF BaZr1-xYxO3-BASED PROTON CONDUCTING ELECTROLYTE USING TEA-METAL PRECURSOR BY THE SOL-GEL METHOD Suttiruk Salaluk 1, Apirat Laobuthee2, Chatchai Veranitisagul3, Panitat Hasin1, Nattamon Koonsaeng1* 2 1 Department of Chemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, Thailand 10900 Department of Materials Engineering, Faculty of Engineering, Kasetsart University, Chatuchak, Bangkok, Thailand 10900 3 Department of Material and Metallurgical Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Klong 6, Thanyaburi, Pathumthani 12110 * E-mail: [email protected]*, Tel. +66 2562 4444 A simple and rapid method, triethanolamine (TEA) solgel, for preparing barium zirconate (BaZrO3, BZ) and yttrium-doped barium zirconate (BaZr1-xYxO3, BZY, with x = 0, 0.15 and 0.20) is reported. Appropriate amount of Y(NO3)3 was introduced to 1:1 mole ratio of Ba(NO3)2 and ZrO(NO3)2 in excess TEA. The asprepared ceramic powders were characterized by X-ray diffraction (XRD). The evolution of the crystalline phase is studied as a function of the calcination temperature (1000 oC, 1200 oC, and 1300 oC in static air). As increasing calcination temperature, the impurity phase, BaCO3, decreases. The XRD pattern of the powder calcined at 1300 oC displayed pure cubic perovskite phase of barium zirconate. In addition, the total conductivity in different doping concentration of yttrium in BaZrO3 has been systematically studied and the highest total conductivity (1.63x10-3 S∙cm-1) was obtained for 15% Y-doped BaZrO3. The electrical properties of the as-prepared BZY showed potential application for electrolyte membrane in solid oxide fuel cell. preparation method. The BZY powder prepared by conventional solid state reaction needs to ball-mill all of the reaction mixture for many hours in zirconia containing with zirconia balls. The mixture was subsequently fired at high temperature. However, repeated milling and post firing may be needed in order to reduce phase contamination of the resulting BZY powder [18-20]. According to time consuming and high energy consumption in solid state process, in recent years, a number of chemistry-based processing routes, such as sol-gel, co-precipitation, freeze drying method combined with vacuum heating, base-hotwater treatment have been developed for preparing BZY powder [2,21,22]. In this research, we present a simple and low cost preparation method for BZY via TEA sol-gel, using metal salts as starting materials instead of expensive and high sensitive metal alkoxides which are difficult to handle in atmospheric moisture. 1. Introduction 2. Materials and Methods Barium zirconate-based perovskites have been extensively received much attention and studied for utilization in various applications, such as proton conducting materials, thermal barrier coating material for aerospace industries, hydrogen sensor and photocatalyst [1-4]. Because barium zirconate (BaZrO3, BZ) has distinctive physical and chemical properties such as high thermal stability, excellent chemical durability, low thermal expansion coefficient and good structural compatibility [5-7]. Currently, a number of reports have been focused on yttrium-doped barium zirconate (BaZr1-xYxO3-δ, BZY) for application in intermediate temperature solid oxide fuel cells (ITSOFCs) due to its extraordinarily high proton in the temperature range 200-500 oC [8-10] and high chemical stability in fuel cell atmosphere [11-16]. Therefore, BZY has a great potential to use as a high efficiency proton conducting electrolyte in protonic ceramic fuel cell [17]. As the differences in physical morphology and chemical composition of BZY play an important role to proton conducting ability of BZY depending on the Barium zirconate precursor was prepared by dissolving Ba(NO3)2 (Acros Organics, 99.9%) and ZrO(NO3)2.H2O (Acros Organics, 99.9%) with the mole ratio of 1:1 in deionized water and heated up to 100 oC, then excess triethanolamine (TEA, Carlo Erba Reagents) was added. The mixture solution was continued heating and stirring for 20 minutes to promote polymerization of the TEA sol-gel. Then water was slowly evaporated to from white sticky gel. The gel precursor was calcined at 1000 oC, 1200 oC and 1300 oC to obtain un-doped BaZrO3 (BZ) powder. The precursor of Y-doped barium zirconate was also prepared by TEA sol gel method, using the same procedure as described. The stoichiometric molar and dopant quantities of ZrO(NO3)2.H2O Y(NO3).6H2O (Acros Organics, 99.9%) were varied with the molar ratio of Ba(NO3)2 : ZrO(NO3)2.H2O : Y(NO3).6H2O as 1 : 0.85 : 0.15, and 1 : 0.80 : 0.20. The gel formed was converted to Y-doped barium zirconate powder by calcination at 1300 oC for 15 h. The calcined products are expressed as BaZr1-xYxO3 Pure and Applied Chemistry International Conference 2015 (PACCON2015) 222 (BZY) where x = 0.15 and 0.20, although the actual composition may be non-stoichiometric with relation to the oxygen. The as-prepared un-doped and Y-doped barium zirconate powders were characterized by X-ray diffraction (XRD) using BRUKER diffractometer (D8 Advance A25) with Cu Kα radiation (0.154 Å), tube voltage 40 kV, and tube current 40 mA. Intensities were collected in the 2θ range between 20o and 90o with step size of 0.02 and a measuring time of 0.5 s at each step. The surface morphology were carried out by Scanning Electron Microscope (SEM, FEI Quanta 450). BZY powders were uniaxial pressed (150 MPa) to bar samples and sintered at 1700 oC for 24 h. Silver paste was painted to each end of the bar and contacted with silver wire. The DC conductivity were measured on bar samples by four-point DC technique under 5% H2/95%He saturated with H2O atmosphere. Fig. 2 comparatively shows XRD patterns of the un-doped and Y-doped BaZrO3 calcined at 1300 °C for 15 h. With increasing the amount of Y(III) dopant, the diffraction peaks of cubic perovskite are broaden, gradually shifted to lower 2-theta angles and the intensities strongly reduced, especially the main 110 hkl diffraction peak. Furthermore, the unit cell parameter increases with increasing Y content as illustrated in Table 1, agreeing well with the fact that the ionic radius of Y(III), 0.9 Å is significantly larger than Zr(IV), 0.72 Å. These implied that the B site, Zr(IV) ion of BaZrO3 perovskite was partly substituted by Y(III) ion to form solid solution of BaZr1-xYxO3 (x = 0.15 and 0.20) so no phase change in XRD was observed. In addition, no separated phase of ZrO2 or Y2O3 was detected. Table 1 The lattice parameter of BaZr1-xYxO3 powders calcined at 1300 oC for 15 h 3. Results and Discussion Fig. 1 shows the XRD diffraction patterns of the un-doped ceramic powders with different calcination conditions. It was found that the samples calcined at lower temperature (1000 oC and 1200 oC) exhibit mixed phases of the cubic BaZrO3 perovskite and BaCO3, agreeing well with standard JCPDS file No. The phase of the bar samples confirmed by XRD showed identical diffraction pattern as that of pure BaZrO3 (Figure 3). The relative densities of all bars, determined by using Archimedes’s principle, were higher than 90% of the theoretical value as presented in Table 2. Selected SEM images of BZ and BZY15 are shown in Fig. 4. For Y-doped sample, smaller grains with approximate size of 1.5 μm was observed, corresponding to lower density of the bar sample Sample composition Abbreviation Lattice parameter (Å) BaZrO3 BaZr0.85Y0.15O3 BaZr0.80Y0.20O3 BZ BZY15 BZY20 4.1923 4.1985 4.2007 Figure 1. XRD patterns of BZ powder calcined at (a) 1000 oC for 5 h, (b) 1200 oC for 4 h, and (c) 1300 oC for 15 h. 06-0399 and 05-0378, respectively. However, as increasing temperature and heating period up to 1300 oC for 15 h, single phase BaZrO3 was obtained. Therefore, this calcinations condition was performed for further experiment. Figure 2. XRD patterns of un-doped and Y-doped BaZrO3 calcined at 1300 oC for 15 h (a) BZ, (b) BZY15, and (c) BZY20. (Table 2). Pure and Applied Chemistry International Conference 2015 (PACCON2015) 223 Table 2 Activation energy and total conductivity of BZY samples at 600 oC Sample Density (% theoretical) BZ BZY15 BZY20 96 94 90 (a) Total conductivity (S∙cm-1) 2.75x10-5 1.63x10-3 0.98x10-3 Ea (eV) 0.59 0.58 0.49 (b) 4. Conclusions BaZr1-xYxO3 (x = 0, 0.15, and 0.20) based perovskites was successfully prepared by a cost effective simple TEA sol gel method. The XRD results clearly showed pure phase of cubic BaZrO3 perovskite for the samples calcined at 1300 oC, 15 h. The highest total conductivity, 1.63x10-3 S∙cm-1 at 600 oC, was obtained for BZY15. We believe that the prepared samples could have potential to be applied for proton conducting in SOFC or in some new application as electronic material for nanodevices. Acknowledgements Figure 4. Cross-section SEM image of the bar sample sintering at 1700 oC for 24 (a) BZ and (b) BZY15. Fig. 5 shows the total conductivity of BZY samples measured as a function of inverse temperature in humidified atmosphere (5%H2/95%He). The total conductivity of the BZ is lower than those of Y-doped sample for about two order of magnitude as presented in Table 2. For BZY15 and BZY20, the total conductivity is ̴ 10-3 S∙cm-1 at 600 oC. The activation energy of all samples is in the range 0.49-0.59 eV. These values are typically observed for proton transport in BZY ceramics [23]. The slightly lower in activation energy of the Y-doped samples compared to that of BZ leads to an increase in mobility of proton, consequently the conductivity increases as presented in Table 2. Therefore, the TEA sol-gel method for preparing yttrium doped barium zirconate has a potential to use as proton conducting electrolyte in solid oxide fuel cell. Figure 5. Total conductivity of the prepared samples measured under wet condition as a function of the inverse temperature (a) BZ, (b) BZY15, and (c) BZY20. Figure 3. XRD patterns of (a) BZ, (b) BZY15, and (c) BZY20 bar sintering at 1700 oC 24 h. This work is supported by Faculty of Science, Kasetsart University, Chemistry Department, Faculty of Science, Kasetsart University and Department of Materials Engineering, Faculty of Engineering, Kasetsart University. A part of this study was also financially support by Development and Promotion of Science and Technology Talents Project (DPST). Thank Prof. Jose Manuel Serra and Dr. Sonia Escolastico, The Instituto de Tecnología Química (ITQ), Spain, for the DC conductivity measurement. References [1] Zajac, W., Rusinek, D., Zheng, K., Molenda, J., 2012, Cent. Eur. J. Chem., 11(4) 2013 471-484. [2] Prastomo, N., Zakaria, N.H., Kawamura, G., Muto, H., Sakai, M., Matsuda, A., 2011, J. Eur. Ceeam. Soc., 31, 2699-2705. [3] Yashima, T.,Koide, K., Fukatsu, N., Ohashi, T., Iwahara, H., 1993, Sens. Actuators, B, 12/14, 697. [4] Song, S., Wachsman, E.D., Dorris, S.E., Balachandran, U., Wachsman, In: E.D, Lyons K. S., Carolyn, M., Garzon, F., Liu, M., Solid State Ionic Devices III (The Electrochemical Society Inc., Pennington, NJ, USA, 1003) 456. [5] Zhang, J.L., Evetts, J.E., 1994, J. Mater. Sci., 29, 77885. [6] Erb, A., Walker, E., Flukiger, R., 1996, Physica C, 258, 9-20. [7] Kumar, H.P., Vijayakumar, C., George C.N., Solomon, S., Jose, R., Thomas, J.K., 2008, J Alloy Compd., 458, 528-31. [8] Bohn, H.G., Schober, T., 2000, J. Am. Ceram. Soc. 83, 768-722. [9] Schober, T. Bohn, H.G., 2000, Solid state Ionic., 127, 351-360. [10] Kreuer, K.D., 2003, Annu. Rev. Mater. Res. 33, 333359. [11] Twahara, H., Yajima, T., Hibino, T., Ozaki, K., Suzuki, H., 1993, Solid state Ionics., 61, 65-69. [12] Katahira, K., Kohchi, Y., Shimura, T., Iwahra, H., 2000, Solid state Ionics., 138, 91-98. [13] Yamazaki, Y., Hernandez-Sanchez, R., Haile, S.M., 2009, Chem. Mater., 21, 2755. [14] Shim, J.H., Gur, T.M., Prinz, F.B., 2008, Appl. Phys. Lett., 92, 2531151. [15] Fabbri, E., D’Epifanio, A., Di Bartolomeo, E., Licoccia, S., Traversa, E., Solid state Ionics., 179, 558. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 224 [16] Haile, S.M., Staneff, G., Ryu, K.H., 2001,J. Mater. Sci. 36, 1149. [17] Fabbri, E., Pergolesi, D., Licoccia, S., Traversa, E., 2010, Solid State ionics., 181, 1043-1051. [18] Tao, S. and Irvine, J.T.S., 2007, J. Solid State Chem., 180(12), 3493-3503. [19] Imashuku, S., Uda, T., Nose, Y., Awakura, Y., 2010, J. Alloys Compd. 490(1-2), 672-676. [20] Park, J.S., Lee, J.H., Lee, H.W., Kim, B.K., 2010, Solid State Ionics, 181(3-4), 163-167. [21] Boschini, F., Rulmont, A., Cloots, R., Vertruyen, B., 2009, J. Eur. Ceram. Soc., 29(8), 1457-1462. [22] Imashuku, S., Uda, T., Nose, Y., Awakura, Y., 2011, J. Alloys Compd., 509(9), 3872-3879. [23] Tong, J., Clark, D., Hoban, M., O'Hayre, R. 2010, Solid State Ionics., 181, 496-50. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 225 DEVELOPMENT OF IMPROVED IRON CHELATORS Filip Kielar1,2* 1 * Department of Chemistry, Faculty of Science, Naresuan University, Phitsanulok, Thailand 2 Centre of Excellence in Biomaterials, Naresuan University, Phitsanulok, Thailand E-mail for Corresponding Author; E-mail: [email protected], Tel. +66 5596 3460, Fax. +66 5596 3401 Abstract: Iron chelation is an important therapeutic tool, for example in the treatment of thalassemia. Development of new iron chelators is still an important task, despite the availability of three iron chelators for clinical practice. Aroyl hydrazone chelators such as salicyl aldehyde isonicotinoyl hydrazone (SIH) possess interesting properties for iron chelation, however, they are susceptible to hydrolytic cleavage. To address this issue a novel hydrazine analogue of SIH, N’-(2hydroxybenzyl)isonicotinohydrazide (BIH) was developed. The binding of BIH to iron was investigated using UV-Vis spectroscopy and through competitive binding assays using nitrilotriacetic acid (NTA) and calcein. Furthermore the ability of BIH to protect against reactive oxygen species damage was evaluated using deoxyribose assay. The results indicate that BIH maintains significant iron binding capability. However, the strength of the binding is weaker than that of SIH, as indicated by the results of the calcein assay test. Furthermore the ability of BIH to protect against oxidative damage has also been diminished in comparison to SIH. On their own these results do not rule out BIH as a potential iron chelator and warrant further investigation 1. Introduction Iron is the most abundant transition element found in the human body [1]. It is indispensable for the proper physiological function taking part in vital and varied processes such as oxygen transport, oxidative phosphorylation, and neurotransmitter synthesis [1,2]. However, iron also has the potential to cause toxic effects, for example through the catalysis of Fenton reaction leading to more damaging reactive oxygen species [1,3]. Therefore the uptake, distribution, storage, and excretion of iron need to be regulated [4]. Failures in iron homeostasis can results in pathologies such as anemia, hemochromatosis, and neurodegenerative diseases [1,5]. Therapeutic interventions can also affect iron status, as is the case of iron overload in Thalassemia patients receiving blood transfusions [6]. Some of the issues relating to iron mediated pathologies can be addressed using iron chelation [1,6,7]. Three chelators (desferrioxamine, desferasirox, and deferiprone) have been approved for clinical practice [6,7]. However, these compounds do possess unwanted side effects [7]. Furthermore, the variation in scenarios where iron chelation might be used therapeutically requires a broader range of chelators to be available. Hydrazone based chelators (e.g. salicylaldehyde isonicotinoyl hydrazone, SIH) are an interesting class of such compounds [8,9]. However, these chelators suffer from relative instability of the hydrazone bond [9]. We have assumed that this property could be improved by changing the link to a hydrazine, which should not suffer from this problem. Herein we report the synthesis and initial characterization of such a hydrazine chelator derived from SIH, N’-(2-hdroxybenzyl)isonicotinohydrazide (BIH). 2. Materials and Methods 2.1 Chemicals and Instruments All chemicals were used as purchased. Salicyl aldehyde, isonicotinoic acid hydrazide, and nitrilotriacetic acid were purchased from Acros. Thiobarbituric acid, sodium borohydride, and 2deoxyribose were purchased from Sigma Aldrich. Iron chloride, ascorbic acid, and trichloroacetic acid were purchased from POCH chemicals. Ferric ammonium and trisodium ortho phosphate were purchased form Ajax Fine Chemicals. Concentrated hydrochloric acid and glacial acetic acid were purchased from Carlo Erba. Hydrogen peroxide (30%) was purchased from Merck. Organic solvents were purchased from Lab Scan and deuterated solvents for NMR were purchased from Cambridge Laboratories. Salicyl aldehyde isonicotinoic hydrazone (SIH) was prepared according to a published procedure [9]. UV-Vis spectra were recorded on an Analytik Jena Specord S100 spectrometer a 298K. Photoluminescence spectra were recorded on a Perkin Elmer LS 55 fluorometer at 298K. NMR spectra were recorded on a Bruker Avance spectrometer operating at 400 MHz (1H). NMR spectra are referenced to the residual solvent peaks. The MS spectra were collected using an Agilent Technologies LC-MS QTOF 6540 UHD Accurate Mass spectrometer. 2.2 Synthesis of N’-(2-hydroxybenzul) isonicotinohydrazide (BIH) A suspension of SIH (1.5 g, 6.2 mmol) and sodium borohydride (470 mg, 12.4 mmol) in MeOH (40 ml) was stirred at room temperature for 1 hour. The solvent was removed under reduced pressure. The residue was dissolved in dichloromethane (100 ml) and washed with a 5% aqueous solution of ammonium chloride (3 x 50 ml). The organic layer was dried over sodium sulphate, filtered, and the solvent was removed under reduced pressure to yield the product as an off white solid (1.1g, 73%). 1H NMR (400 MHz, DMSOd6) δ 3.96 (2H, d, J = 6.0, CH2), 5.64 (1H, m, NH Pure and Applied Chemistry International Conference 2015 (PACCON2015) 226 amine), 6.74 (1H, dd, J = 7.4, J = 7.4, CH-Ph), 6.79 (1H, d, J = 8.0, CH-Ph), 7.08 (1H, dd, J = 7.8, J = 7.8, CH-Ph), 7.40 (1H, d, J = 7.4, CH-Ph), 7.70 (2H, d, J = 5.8, CH-Py), 8.70 (2H, d, J = 5.8, CH-Py), 9.61 (1H, s, OH), 10.43 (1H, d, J = 6.0, NH amide). HR-MS (ES+) C13H14N3O2 requires 244.1086 [M+H]+; found 244.1080. 2.3 UV-Vis titration with ferric ammonium citrate (FAC) Stock solutions of SIH and BIH (100 mM) were prepared in DMSO. Stock solution of FAC (10 mM) was prepared in 50 mM sodium phosphate buffer (pH 7.4). A 100 µM solution of the ligands was prepared by diluting the stock solution in the phosphate buffer. The titration was carried out by adding aliquots of the FAC stock solution to the solution of the ligands. Each addition was followed by a 10-minute equilibration period. BIH (100 mM) were prepared in DMSO and then diluted to 100 µM in phosphate buffer. Sodium phosphate buffer containing 0.1% (v/v) DMSO was prepared. The reaction mixtures were prepared by mixing adding the reagents in the following order: chelator (0-90 µM), FeCl3 (10 µM), 2-deoxyribose (15 mM), hydrogen peroxide (200 µM) and ascorbic acid (2 mM). The reaction mixture volume was adjusted to a total volume of 1 ml using phosphate buffer containing 0.1% DMSO. The reaction mixtures were incubated at 37oC for 1 h and then quenched with trichloroacetic and thiobarbituric acid solutions (1 ml each). The quenching reaction was carried out at 100oC for 20 minutes. Absorbances of the mixtures were recorded at 532 nm after cooling to room temperature. The results are displayed as ratio with absorbance of the sample containing no chelator. The experiment was carried out in triplicate. 3. Results and Discussion 2.5 Iron binding competition with calcein Stock solution of SIH and BIH (4 mM) were prepared in DMSO. Stock solution of calcein (400 µM) was prepared in DMSO. Stock solution of FAC (1 mM) was prepared in phosphate buffer. Calcein and FAC were mixed and diluted in the phosphate buffer to final concentrations of 2 and 4 µM respectively. The solutions were left to equilibrate for 1 h in darkness. Aliquots of the SIH and BIH solutions were added to the prepared calcein iron mixtures (final concentration 8 µM) and the solutions were left to equilibrate for 1 h in darkness. Appropriate volumes of DMSO were added to the samples so that final DMSO concentration in all samples was 1%. A positive control was prepared containing calcein only. A negative control was prepared containing calcein and FAC but no added iron chelator. Fluorescence spectra were collected after diluting the mixtures 10x with phosphate buffer. The fluorescence spectra were collected between 470 and 650 nm with excitation at 460 nm. The experiment was performed in duplicate. 2.6 Deoxyribose assay Stock solutions of dexoyribose (300 mM), hydrogen peroxide (10 mM), ascorbic acid (100 mM), and trichloroacetic acid (2.8% w/v) were prepared in deionized water. Stock solution of FeCl3 (1 mM) was prepared in 10 mM HCl. Stock solution of thiobarbituric acid (1% w/v) was prepared in 50 mM sodium hydroxide solution. Stock solutions of SIH and 3.1 BIH synthesis BIH has been synthesized by a reduction of SIH with sodium borohydride in methanol (Figure1.). It was observed that the use of bigger excess of sodium borohydride and shorter reaction times lead to a cleaner product. BIH was characterized using NMR and MS spectroscopies Figure 1. Synthesis of BIH 3.2 Investigation of iron binding using UV-Vis spectroscopy 2 1.5 Abs. 2.4 Iron binding competition with nitrilotriacetic acid (NTA) A solution of 100 µM SIH or BIH and 50 µM FAC in phosphate buffer was prepared and left to equilibrate for 1 h. A stock solution of NTA (10 mM) was prepared in the phosphate buffer. An aliquot of the NTA stock solution was added to the equilibrated solution of the ligands and FAC. The solution was left to equilibrate for 1 h before recording the UV-Vis spectra. 1 100 µM SIH SIH + 10 µM FAC SIH + 20 µM FAC SIH + 30 µM FAC SIH + 40 µM FAC FAC + 50 µM FAC 0.5 0 200 250 300 350 400 450 500 550 600 Wavelngth (nm) Figure2. UV-Vis spectra of titration of SIH (100 µM) with ferric ammonium citrate (pH 7.4, 298K) The UV-Vis spectra of both SIH and BIH (100 µM) were recorded in phosphate buffer (50 mM, pH 7.4). The UV-Vis spectra of SIH and BIH are shown Pure and Applied Chemistry International Conference 2015 (PACCON2015) 227 in Figure 2 and Figure 3 respectively. Figures 2 and 3 also show the changes in the UV-Vis spectra of SIH and BIH resulting from the addition of ferric ammonium citrate (FAC). These spectra indicate the formation of the iron complexes of these ligands. 1 0.8 100 µM BIH BIH + 10 µM FAC BIH + 20 µM FAC BIH + 30 µM FAC BIH + 40 µM FAC BIH + 50 µM FAC 1.2 1 0.8 0.4 I/I 0 Abs. 0.6 Iron in biological setting is capable of promoting the effects of oxidative stress through the Fenton reaction. Evaluation of the effect of iron chelation on Fenton reaction can be performed using the deoxyribose assay. Effects of 10 to 90 µM SIH and BIH on the results of the deoxyribose assay are shown in Figure 6. 0.2 0.6 0 200 250 300 350 400 450 500 550 600 Wavelength (nm) Figure 3. UV-Vis spectra of titration of BIH (100 µM) with ferric ammonium citrate (pH 7.4, 298K) The binding interaction between SIH and BIH was further investigated using a competition experiment with nitrilotriacetic acid (NTA). Complexes of SIH and BIH with Fe3+ (50 µM) were prepared and their UV-Vis spectra were recorded (Figure 4). NTA (100 µM) was added to these complexes and the UV-Vis was recorded after an equilibration period (Figure 4). 0.4 0.2 Calcein Fe SIH BIH Abs. 1 + + + - SIH BIH 1 0.8 0.8 0 50 µM FeSIH 50 µM FeBIH FeSIH + 100 µM NTA FeBIH + 100 µM NTA 100 µM NTA + + + 1.2 A/A 1.2 + + - Figure 5. Graph of normalized calcein fluorescence intensity showing the effect of quenching by iron and the recovery of luminescence upon the addition of iron chelators (SIH, BIH) 1.6 1.4 + - 0.6 0.4 0.6 0.2 0.4 0 0.2 0 200 250 300 350 400 450 500 550 600 Wavelength (nm) Figure 4. UV-Vis spectra of iron complexes with SIH and BIH before and after the addition of NTA (pH 7.4, 298K). 3.3 Investigation of iron binding using calcein Further insight into the binding of Fe3+ with SIH and BIH was obtained using the fluorescent metal indicator calcein (Figure 5). This experiment evaluates the ability of the chelators to restore the fluorescence of calcein after its quenching with Fe3+ ions. The results comparing the properties of SIH and BIH are shown in Figure 5. 0 20 40 60 80 Concentration (µM) 100 Figure 6. Graph of normalized absorbance showing the results of deoxyribose assay carried out in the presence of SIH and BIH (0-90 µM). BIH has been synthesized using a simple reduction reaction of SIH (Figure 1). The main issue with this reaction is the decomposition of the product under the reaction conditions with extended reaction times. Therefore a fast reaction using excess of NaBH4 was deemed preferable and could yield clean product without a formal purification step. UV-Vis spectra of SIH and BIH (100 µM) were recorded in phosphate buffer (50 mM, pH 7.4) and can be seen as the solid red traces in Figures 2 and 3 respectively. SIH exhibits major peaks at 225 nm, 288 Pure and Applied Chemistry International Conference 2015 (PACCON2015) 228 nm, and 328 nm as well as a broad shoulder at 410 nm. In comparison BIH exhibits significantly blue shifted UV-Vis spectrum with peaks at 225 nm and 270 nm. The spectrum also contains a broad shoulder 330 nm. The absorbances of the peaks of BIH are also significantly smaller than in the case of SIH. These differences are consistent with the change of the carbon nitrogen hydrazone double bond in SIH to a single hydrazine bond in BIH. Figures 2 and 3 also show the changes in the UV-Vis spectra when titrated with Fe3+ ions in the form of FAC (10 to 50 µM). The changes in the spectra, especially the formation of the broad features at 450 and 365 nm for SIH and BIH respectively, are indicative of the formation of Fe3+ complexes of these ligands [10]. The interactions of the ligands SIH and BIH with Fe3+ were further investigated through competitive binding assays using nitrilotriacetic acid (NTA) and calcein. The results of the experiment with NTA are shown in Figure 4. In this case the complexes of SIH and BIH with Fe3+ (50 µM) were formed first followed by the addition of NTA (100 µM). NTA is a metal chelator with modest affinity for Fe3+ ions. The minimal changes in the spectra of the SIH and BIH iron complexes upon NTA addition indicate that NTA was unable to remove iron from these complexes to any significant extent. This result has been previously observed for SIH. Therefore, both SIH and BIH can be regarded as having binding affinity for Fe3+ at least as strong as that of NTA. The final test employed in the investigation of iron binding properties of the ligands SIH and BIH was the investigation of their interaction with the iron complex of the metal sensitive fluorophore calcein (Figure 5) [10]. The fluorescence of calcein is quenched upon its complexation with Fe3+ ions, as shown in the first two bars of Figure 5. The strength of a chelator can be deduced from its ability to restore calcein fluorescence by competitively removing iron from its calcein complex. The third and fourth bars in Figure 5 show that 8 µM SIH was able to completely restore calcein fluorescence whereas BIH was only able to restore it to 75 % of the original value. It should be noted that BIH was able to restore calcein fluorescence fully at higher concentrations and that SIH actually lead to the full recovery even at lower concentrations (results not shown). These results indicate that BIH is a weaker iron binder than SIH. Iron can be toxic in biological systems given its ability to promote oxidative stress through the Fenton reaction. Ability of iron to take part in this reaction and the extent of damage it can do depends on its coordination environment and its redox properties [10]. Deoxyribose assay is a method of testing the ability of chelators to protect against iron mediated oxidative damage [10]. The results of this assay in the presence of SIH and BIH are shown in Figure 6. The data is reported as ration with the absorbance in the absence of the chelators, which means that values below 1 indicate protection against oxidative stress, whereas values above 1 mean the added compound promotes oxidative stress. As can be seen from Figure 6, both SIH and BIH give A/A0 values below 1. However, the protection offered by BIH seems to be significantly lower than that offered by SIH as the final A/A0 values for these compounds are 0.8 and 0.4 respectively. These results indicate that even though BIH is not very effective in protecting against iron mediated oxidative stress it does not exacerbate it and thus could be used for iron chelation in situations where prevention of oxidative stress is not the main goal. 4. Conclusions A novel aroyl hydrazine compound BIH has been synthesized and its ability to bind iron has been evaluated and compared to its parent hydrazone iron chelator SIH. It has been found that BIH maintains significant iron binding affinity, however, it is reduced when compared to SIH. Furthermore, the ability of BIH to protect against iron mediated oxidative stress is also reduced when compared to SIH. Despite this BIH is an interesting compound that should be further tested as very high binding strength and great efficacy in protecting against oxidative stress are not the only parameters important for biological iron chelators. Acknowledgements This research was financially supported by Naresuan Univesity DRA grant No. R2556C110. References [1] Alessio, E., Editors, 2011, Bioinorganic Medicinal Chemistry, Wiley-VCH Verlag GmbH, Weinheim, 307350. [2] Crichton, R.R., Dexter, D.T., Ward, R.J., 2011, J. Neural. Transm., 118, 301-314. [3] Theil, E.C., Goss, D.J., 2009, Chem. Rev., 109, 45684579. [4] Andrews, N.C., Schmidt, P.J., 2007, Annu. Rev. Physiol., 69, 69-85. [5] Crichton, R., Dexter, D., Ward, R., 2011, Monatshefte Fur Chemie, 142, 341. [6] Sharpe, P.C., Richardson, D.R., Kalinowski, D.S., Berndahrd, P.V. 2011, Curr. Top. Med. Chem., 5, 591607. [7] Zhou, T., Ma, Y., Kong, X., Hider, R.C., 2012, Dalton Trans., 21, 6371-6389. [8] Bendova, P., Mackova, E., Haskova, P., Vavrova, A., Jirkovsky, E., Sterba, M., Popelova, O., Kalinowski, D.S., Kovarikova, P., Vavrova, K., Richardson, D.R., Simunek, T., 2010, Chem. Res. Toxicol., 23, 1105-1114. [9] Hruskova, K., Kovarikova, P., Bendova, P., Haskova, P., Mackova, E., Stariat, J., Vavrova, A., Vavrova, K., Simunek, T., 2011, Chem. Res. Toxicol., 24, 290-302. [10] Kielar, F., Helsel, M.E., Wang, Q., Franz, K.J., 2012, Metallomics, 4, 899-909. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 229 ONE-POT SYNTHESIS OF CuO/ZnO NANOSTRUCTURE WITH DISCRETE CuO NANOPARTICLES ON ZnO HEXAGONAL PLATE Karnrat Hongpo1, Karaked Tedsree2* 1,2Nanocatalysis * laboratory, Department of Chemistry, Faculty or Science, Burapha University, 20131, Thailand 1,2Center of Excellent on Environmental Health and Toxicology (ETH) E-mail for Corresponding Author; E-mail: [email protected], Tel. +66 80565 9915 Abstract: A new surface-modified CuO/ZnO nanostructure was sucessfully synthesized by one-pot hydrothermal method. Heating an aqueous solution of zinc acetate and copper nitrate in the presence of hexamethylenetetramine )HMT( at 97°C and calcination at 350°C gave discrete CuO nanoparticles with seggregrated ZnO hexagonal plate. The particle size and thickness of ZnO nanoplate can be tuned by varying mole percent of Cu2+ added. The particle sizes and shape of the obtained products were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Crystal structure was identified by X-Ray diffraction (XRD). Chemical composition was confirmed by EDX analysis. Surface composition and oxidation states of metals were studied by X-Ray photoelectron spectroscopy (XPS). Photoluminescence was used to further characterize their optical properties. 1. Introduction ZnO nanostructures have been studied extensively over the last decade due to their interesting size- and shape-dependent properties. It can be prepared on a large scale at low cost by simple solution route, such as chemical precipitation, sol-gel and solvothermal/ hydrothermal process, etc. [1-2]. Efforts have been focused on the preparation of ZnO nanostructures with various morphologies including the nanorod, nanoplate, nanobelt and flower-like [3-4]. It has been reported that the hexagonal platelike particles of ZnO show superiority to rod-shaped particles as photocatalysts due to their large specific surface area and high population of polar (0001) faces [5]. Therefore, much attention has been paid on the synthesis of its plate like nanostructure. In addition, considerable attention has been paid to surface modification of ZnO nanostructure by doping with selective elements such as Ag Au and Cu metal [6]. These can induce dramatic changes in the electrical, optical and magnetic properties. Different methods for the preparation of Cu-doped ZnO nanostructure (Cu/ZnO) can be found in literature such as impregnation, co-precipitation, sol–gel, microemulsions, hydrothermal and polyol process [710]. Of all these methods, hydrothermal is gaining increasing popularity owing to simple operation and the possibility to large-scale synthesis. Different sizes, shapes and morphologies can be systematically obtained by optimising appropriate experimental parameters such as type and concentration of zinc and Cu precursor, pH, reaction temperature and capping agent, etc. It has been known that particle size, composition, dispersion of Cu species on ZnO was found to influence on its activity and selectivity in catalytic hydrogenation of CO2 to methanol. Currently, shape control selectivity in nanocatalysts has clearly been demonstrated with the type of surface sites expressed at the catalyst surface. Tsang and co-workers [11] prepared Cu/ZnO by physical mixing of ZnO nanoplates with Cu nanoparticles. Their results clearly showed that surface modified ZnO nanostructures with (002) polar facet of platelike ZnO nanoparticles gives a much stronger electronic interaction with Cu nanoparticles than other facets and they also showed high selectivity of this reaction by this mixture. Herein, we report the synthesis method of a novel surface-modified CuO/ZnO nanostructure by simple one-pot single-step hydrothermal method. Initimate mixture of discrete CuO nanoparticles seggregrated from ZnO nanoplates was obtained. The structure was confirmed by various techniques. In addition, for the potential application in photocatalysis, the optical properties of the samples were also explored. 2. Materials and Methods 2.1 Materials Zinc acetate dihydrate (Zn(CH3COO)2•2H2O) and hexamethylenetetramine (C6H12N4) were purchased from Sigma Aldrich. Cupper nitrate trihydrate (Cu(NO3)2.3H2O) was purchased from )Qrec, New Zealand( 2.2 Synthesis of Surface-modified CuO/ZnO Nanostructures CuO/ZnO nanostructures were synthesized by hydrothermal method. Typically 3.00 g of zinc acetate dihydrate, 1.92 g of hexamethylenetetramine and 0.0997 g of cupper nitrate (3 mol %) were dissolved in 24 mL of deionized water. After stirring for 10 min, the solution was transferred into a 50 ml Teflon-lined autoclave and maintained at 97°C for 5 h. The white precipitate was collected by centrifugation and washed several times with deionized water and followed by ethanol. The products were dried at 100°C for 2h and calcination at 350°C for 3 h. The percentage of Cu loading was studied between 0.25, 0.5, 1.0, 3.0, 5.0 and 10 mol %. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 230 ZnO hexagonal plate was synthesized by following the literature [12]. Typically, the preparation method was performed the same method of surface-modified CuO/ZnO nanostructures (section 2.2), but the reaction was carried out in the absence of Cu(NO3) precursor. 2.3 Characterization The crystal structure of the synthesized CuO/ZnO hexagonal plate was characterized by X-ray powder diffraction (XRD). The XRD-patterns were acquired on a Bruker AXS D8 Advance diffractometer using Cu Kα radiation as an X-Ray source. Transmission electron microscope (TEM) and scanning electron microscopy )SEM( were used to indentified size, shape and distribution of the particles. TEM observations were conducted on a JEOL JEM 2011 microscope operated at 200 kV. The SEM images were recorded on a LEO 1450 VP electron microscope (LEO, England). Energy-dispersive X-ray spectrometer (INCA-OXFORD, England) was connected to SEM used for element analysis and elemental distribution. Photoluminesence spectroscopy was used to study the optical property of samples. The photoemission of colloidal CuO/ZnO hexagonal plate in water was recorded at room temperature using a model FP-6200 )Jasco, Japan) with an excitation wavelength of 370 nm. Surface composition of the particles was analyzed by Scienta ESCA-300 high-resolution X-ray photoelectron spectrometer. 3. Results and Discussion ZnO hexagonal plate was prepared by hydrothermal method. Zinc acetate dihydrate was used as a precursor in the presence of HMT. HMT plays an important role to supply hydroxyl ions which react with Zn2+ ions to form Zn(OH)42- [13]. Acetate anion was widely accepted to control the formation of plate structure. It could be adsorbed on the (0001) surface of ZnO and block the contact between the growth units and the (0001) surface [14]. In addition, HMT was accepted to control the particle shape of ZnO. Mixing of Cu2+ ion in the preparation reaction, the chemical reaction processes for the generation of the CuO on ZnO hexagonal plate was proposed in equation 1-3. Zn2+ + Cu2+ + xOH - (1) Cu(OH)2/ZnO (2) 97°C Zn(OH)42- + Cu(OH)2 Cu(OH)2/ZnO Zn(OH)42- + Cu(OH)2 Hydrothermal Calcination 350°C CuO/ZnO (3) SEM and TEM images of surface-modified CuO/ZnO nanostructures with different % Cu2+ loading after annealing at 350°C are shown in Figure 1 and 2. The particle size and chemical compositions of the samples are also shown in Table 1. Figure 1. SEM images of a) ZnO hexagonal plate and surface-modified CuO/ZnO nanostructures b) 1 mole % c) 3 mole % and d) 5 mole % of Cu2+loading Figure 2. TEM images of surface-modified CuO/ZnO nanostructures a) 3 mole % of Cu2+ loading b) high magnification of the image, average particle size diameter of CuO is about 9.54 ± 1.85 nm. Table 1: Particle size and chemical compositions of the synthesized ZnO and surface-modified Cu/ZnO nanostructures Mole % Cu loading Calculation EDX 0 1.0 3.0 5.0 10.0 2.5 2.9 4.5 7.8 Particle size of ZnO Diameter Thickness (nm) (nm) 1427 ±216 873 ±149 1357 ±363 554 ±96 1311 ±160 200 ± 48 1386 ±198 189 ±67 1227 ±500 107 ± 23 SEM coupled with EDX measurements can be confirmed the incorporation of Cu species into the ZnO matrix. The atomic ratio between Cu and Zn (analysis by EDX) was found close to the theoretical calculation. It can be noticed that increasing mole % of Cu2+ loading, the thickness of ZnO hexagonal plate decreased significantly while the particle sizes tend to slightly decrease. Decreasing of the thickness of hexagonal plate when doping with Cu2+ may affect to growth rate of ZnO. Generally, ZnO grows preferentially along [001] direction in aqueous solution because of the lowest surface energy of (001) facet. And the growth velocity along [010] directions is slower than that of [001] direction, Pure and Applied Chemistry International Conference 2015 (PACCON2015) 231 resulting in rod-like structure. However, in the presence of HMT, it might be adsorbed on the (001) facets of ZnO crystals and significantly decrease the growth rate of these facets, resulting in platelike structure. [15] In case of adding Cu2+, it may serve as a surface-passivating agent in the reaction system the same as HMT. A schematic diagram of the proposed growth mechanisms of CuO/ZnO hexagonal plate is shown in Figure 3. It is possible that the growth process took place at the interface of the Zn terminated facets by combination of Cu(OH)42- species and the growth unit Zn(OH)42-. The enhanced passivation effects become stronger as the content of Cu2+ ions increased, which can be confirmed by the decrease in thickness of the hexagonal plate from 554 nm to 90 nm. These results were in accordance with the studied of Liu et al. [16]. the CuO peak in the low contents (3 mole %) is due to the high dispersion of the small clusters. In addition, there is no significant shift of all diffraction peaks, implying that no Zn1-xCuxO solid solution is formed. This indicates the segregation of CuO particles in the grain boundaries of ZnO crystallites rather than going into the lattice of ZnO although the ionic radius of Cu (Cu2+ = 0.057 nm) is almost same as zinc site in ZnO (Zn2+= 0.060 nm [17]. In addition, as Cu2+ ions prefer octahedral environment with Jahn Teller elongation in z axis while Zn2+ cannot support this. Thus, structurally mismatch hence no evidence of cross substitution from XRD. The surface composition and chemical state of the samples have been investigated by XPS. Figure 5 displays the XPS spectrum of Zn2p O1s and Cu2p of the ZnO sample with 3 mole % of Cu2+ loading. Figure 3. Schematic diagram of the proposed formation mechanisms of surface-modified CuO/ZnO nanostructure The crystal phase and phase purity of the synthesized ZnO and surface-modified CuO/ZnO samples prepared with different Cu2+ loading were examined by XRD. The results are shown in Figure 4. Figure 4 XRD patterns of a) ZnO and Cu-modified ZnO with b) 3 and c) 10% mole of Cu loading. The appearance of the characteristic ZnO peaks at 31.74, 34.40, 36.24, 47.48, and 56.62 corresponding to the (100), (002), (101), (102), and (110) crystal plane, which is comparative with the XRD pattern of ZnO with hexagonal wurtzite structure (JCPDS file no. 361451). The crystalline form of ZnO has not been changed by loading Cu. The small Cu diffraction peaks appeared at 2θ = 35.52 and 38.98 on only on the high loading samples (10 mole %) can be indexed to face-centered–cubic (fcc) of Cu. The disappearance of Figure 5. XPS spectrum of a) O1s b) Zn2p c) Cu2p of surface- modified CuO/ZnO nanostructure The asymmetric peak observed in the O1s region was resolved into two peaks. The peak with low binding energy (530.3 eV) corresponds to O2- ions in a normal ZnO wurtzite structure, while the second one centered at 531.8 eV may be attributed to different kinds of species, such as adsorbed hydroxyl group or O2- ions in the oxygen deficient regions within the ZnO matrix [18]. The Zn2p core level located at 1021.2 and 1044.2 eV attributed to Zn2p1/2 and Zn2p3/2 eV respectively, typicaly ZnO. The binding energies at 933.4 and 953.8 eV were Cu2p3/2 and Cu2p1/2, respectively. Broadening of the peaks were observed. The strong sattlelite peaks observed at 942.4 eV was clearly showed the presence of Cu2+ species. This result suggested the presence of CuO. Surface compositions of the sample determined by XPS analysis were 44.20 % atom for Zn2+, 51.15 % atom for all species of oxygen and 4.65 % A for all Cu and Cu ion species. It can be seen that Zn:Cu ratios was higher than that the compositions from theoretical calculation and EDX analysis (Table 1). This is an indication of segregation of the Cu doping on the surface of ZnO. This results was in accordance with the studied of Bellini, J. et al. [9] Surface defect plays an important role in the photocatalytic activity. This work, photoluminesence spectroscopy was used to investigate defects. Photoluminescence (PL) spectra of the synthesized Pure and Applied Chemistry International Conference 2015 (PACCON2015) 232 ZnO hexagonal plate and surface-modified CuO/ZnO at different mole % Cu2+ loading are shown in Figure 6 Figure 6. Room temperature PL spectra of surfacemodified CuO/ZnO nanostructure at excitation 370 nm In visible region, a strong violet emission centered at 412 nm and a broad band of blue and green emission was observed at 465 nm and 530 nm, respectively. These visible emissions are due to various transitions of defects such as Zn interstitial and oxygen vacancies, etc [20]. Increasing Cu contents of CuO/ZnO samples, the photoluminescence intensity decreased considerably in this region. Therefore, the incorporation of Cu impurities during the growth will contribute to the decreasing of defective levels . Q. 2007, 61, 703–707. [10] Tincekic, T.G. and Boz, I., 2008, Bull. Mater. Sci., 31, 619–624 [11] Liao, F., Huang Y., Ge J, Zheng W, Tedsree K., Collier P., Hong X. and Tsang S. C., 2011, Angew. Chem. Int. Ed., 50, 2162–2165. [12] Hu, J., Fan, Y., Pei, Y., Qiao, M., Fan, K., Zhang, X. and Zong, B. 2013, ACS Catalysis, 3, 22802287. [13] Li, B. and Wang, Y. 2009, J. Phys Chem C, 114, 890-896. [14] Ashford, S., 2007, J. Phys Chem B, 127-154. [15] Chu, D. and Li, S., 2012, New journal of glass and Ceramics, 2, 13-16. [16] Liu, J., Xu L., Wei, B., Wei, L., Gao, H. and Zhang, X, 2011, Cryst Eng Comm, 13, 1283– 1286. [17] Li, J. C., Cao Q., Yan, X., Hou, Wang, B. F. and Ba, D. C., 2013, Superlattices and Microstructures, 59, 169–177. [18] Atanasova1, G., Dikovska A. O., Stankova, M., Stefanov, P. and Atanasov, P. A., 2012, Journal of Physics: Conference Series, 356, 012036. [19] Bellini, J., Morelli, M. and Kiminami, K., 2002, J. Mater. Sci. Mater. Electron, 8, 485-489. [20] Ischenko, V., Polarz, S., Grote, D., Atavarache, V., Fink, K. and Driess, M. 2005, Funct. Mate, 15, 1945-1954. 4. Conclusions We have successfully synthesized a novel CuOmodified ZnO nanostructure by a single step hydrothermal method. Their structure contains discrete CuO segregation on the surface of ZnO hexagonal plate. Moreover, the particle size and thickness of ZnO can be tuned by varying mole % of Cu2+ incorporation. Acknowledgements We gratefully center of excellence on Environmental Health and Toxicology for the financial support. References [1] Baruah, S. and Dutta J., 2009, Sci. Technol. Adv. Mater, 10, 013001- 013018. [2] Liu, J., Huang, X., Li, Y., Zhong, Q. and Ren, L., 2006, 60, 1354–1359. [3] Li, B. and Wang, Y., 2010, J. Phys. Chem. C, 114, 890–896. [4] Xu, F., Yuan, Z. Y., Du, H. G., Halasa, M., and Su, B. L. 2007, Appl. Phys. A, 86, 181–185. [5] Mclaren A., Valdes-Solis, T., Li, G. Q., and Tsang S. C. 2009, J. Am. Chem. Soc., 131, 12540. [6] Xie, W., Li, Y., Sun, W., Huang, J., Xie, H. and Zhao, X., 2010, J. Photoch and Photobio A: Chemistry, 216, 149–155. [7] Behrens M. and Schlögl, R., 2013, Anorg. Allg. Chem., 639, 15, 2683–2695. [8] Rahmati, A, Sirgani A. B., Molaei, M. and Karimipour, 2014, Eur. Phys. J. Plus, 129, 250 [9] Zhao, Y. M., Li, Y, H., Jin, Y. Z., Zhang, X, P., Hu, W. B., Ahmad, I., McCartney, G. and Zhu, Y. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 233 OPTICAL SENSING PROPERTIES OF PLASTICIZED POLYMERIC MEMBRANE INCORPORATING N,N'-ETHYLENEBIS(SALICYLIMINE) AS TRANSITION METAL ION-SELECTIVE IONOPHORE Jiraporn Pandoidan1, Phetlada Kunthadee1* 1 Department of Chemistry, Faculty of Science, Maejo University, San Sai, Chiang Mai, 50290, Thailand * E-mail: [email protected], [email protected] Tel. +66 5387 3530-1, Fax. +66 53873548 Abstract: Novel polymeric membrane optical sensors for the highly selective detection of transition metal ions using N,N'-Ethylenebis(salicylimine) (salen) as ionophore have been developed. The salen ligand was incorporated into plasticized PVC polymer matrix along with the presence of cation exchanger to enhance ion-ligand interaction. Optical sensing properties of prepared sensors were then comparatively examined towards cations such as Al3+, Fe2+, Cr3+, Co2+, Ni2+, Cu2+, and Zn2+, in terms of membrane sensitivity, selectivity, response time, and linear concentration range, using UVVis spectrophotometric technique. Preliminary results showed that the proposed membranes tended to be selective to Fe2+ over other cations with the working concentration range of 10-4 to 10-2 M. ions [3-7]. In this work, we aim to immobilize the ionophore in the membrane while the cation analyte are presented in aqueous solutions. Salen is soluble in polar organic solvents and therefore suitable being chosen as ionophore in polymeric membrane for the detection of metal cations such as Al3+, Fe2+, Cr3+, Co2+, Ni2+, Cu2+, and Zn2+ via the reversible metal chelation at the membrane-aqueous interphase. Optical sensing properties and important characteristics of the fabricated sensors will be investigated in order to find the most selective metal ions and then the high performance ion-selective optical sensor is expected to be applied in real samples. 2. Materials and Methods 1. Introduction Optical sensor, or optode, is one type of chemical sensors in which electromagnetic (EM) radiation is used to generate the analytical signal relating to the interaction of this radiation with the sample and the concentration of the analyte. Typically, an optical chemical sensor consists of a chemical recognition phase (sensing element or receptor) coupled with a transduction element [1]. Optical sensor is recently one of analytical devices employing for the measurement of ions due to its several benefits such as simplicity, high sensitivity and selectivity, good reversibility, and fast response. It is well-known that the selectivity of poly(vinyl chloride) or PVC membranes correlates with their transport selectivity and also the extraction selectivity. The most important component in a polymeric membrane sensor is the ionophore which contains the sensing unit that can bind and transfer the most selective ion across the membrane. Another important component is the ion exchanger which functions as a balance charge, enhancing the metal ion transfer and limits the co-anions entering the membrane [2]. N,N'-Ethylenebis(salicylimine) or ‘salen’ is one of the chelating ligands widely used in coordination chemistry. The structure of this compound is depicted in Figure 1. Metal-salen complexes and their derivatives are commonly prepared and studied using several techniques including spectrophotometric methods. However, most studies have been carried out in the same media/phase and might not be able to reuse due to the non-reversible interaction. There are also a few reports on electrochemical and optical sensing properties of salen and its derivatives towards typical 2.1 Reagents and solutions N,N'-Ethylenebis(salicylimine) or salen ligand was prepared by the condensation of ethylenediamine and salicylaldehyde according to the previous report [8]. Potassium tetrakis(p-chlorophenyl)borate (KTpClPB), Tetrahydrofuran (THF), high molecular weight poly(vinyl chloride) (PVC), and o-nitrophenyl octyl ether (o-NPOE) were purchased from Fluka and Merck. Analytical reagent grade of metal salts: Co(NO3)2·6H2O, FeSO4·7H2O, Al(NO3)3·9H2O, Cu(NO3)2·2.5H2O, Cr(NO3)3·9H2O, NiSO4·6H2O, ZnSO4·7H2O were obtained from Unilab, Ajax Finechem, and Volchem. All solutions of metal salts were prepared with ultrapure water. 2.2 Instrumentation The UV-Vis absorption spectra were recorded on a double beam Hitachi (U-2900) spectrophotometer with 1.0-cm quartz cells, in the wavelength range between 200 and 1000 nm. N OH N HO Figure 1. Chemical structure of salen ligand: N,N'Ethylenebis(salicylimine). 2.3 Membrane preparation Pure and Applied Chemistry International Conference 2015 (PACCON2015) 234 Polymeric membranes prepared for UV-Vis measurements consisted of salen as ionophore (1% w/w), KTpClPB as cation exchanger (75% relative to the ionophore), and PVC: o-NPOE plasticizer (1 : 2 w/w), with a total amount of 100 mg. All components were dissolved and stirred in 1.5 mL of THF for 30 minutes, giving a transparent homogeneous paleyellow cocktail solution. A cover glass with 22 mm × 22 mm dimensions was cut to fit into standard spectrophotometer cell. The membrane slide was prepared by pipetting 20 μL of the casting membrane solution onto a glass slide and the sovent was then completely removed before the measurements (see Figure 2). 2.4 Analytical procedure Spectrophotometric measurements were carried out to investigate the response of optical membrane towards metal cations. The membrane slide was placed vertically inside the quartz cell containing 2 mL of metal ion aqueous solution for 5, 10, 20, and 30 minutes. The absorption spectra were recorded against the blank membrane in ultrapure water as a reference over the wavelength range of 200-1000 nm. The concentration of cations was varied from 10-7 to 10-2 M to examine the linear working range. salen ligand salen + Al(III) salen + Co(II) salen + Fe(II) 0.15 423 0.1 Abs 413 0.05 0 350 450 550 650 wavelength (nm) Figure 3. Spectral changes of salen ligand with different metal ions (10-3 M) (the spectra for Cr3+, Co2+, Ni2+, Cu2+, and Zn2+ are not shown here). A series of UV-Vis titrations was carried out to confirm the recognition mechanism of salen towards Fe(II) ion. As illustrated in Figure 4, the absorption spectrum increases gradually with increasing Fe(II) concentration, suggesting the complexation between this ion and salen via N and O donor atoms. Moreover, the cationic size effect probably played a role in discriminating Fe2+ from other cations. Series1 salen ligand Fe(II) Series3 10-6 M Fe(II) Series4 10-5 M Fe(II) Series5 10-4 M Fe(II) Series6 10-3 M Fe(II) Series7 10-2 M Fe(II) Series2 10-7 M 0.2 0.15 Abs 0.1 0.05 0 350 Figure 2. Preparation of a membrane slide and UV-Vis absorbance measurement. 400 450 500 550 600 650 Wavelength (nm) 700 750 800 Figure 4. Absorption spectra of a membrane slide in the presence of different concentrations of Fe(II). 3. Results and Discussion N,N'-Ethylenebis(salicylimine) contains a nitrogen and oxygen donor atom which could form internal bonds with hard metal ions. UV-Vis absorbance measurements were made to review the complexation properties between salen ligand and various metal cations in solutions (10-3 M) such as Al3+, Fe2+, Cr3+, Co2+, Ni2+, Cu2+, and Zn2+ spectrophotometrically. The preliminary results showed the characteristic band of salen ionophore in the absence of metal ions at 413 nm in Figure 3. Upon addition of 10-3 M of Al3+ and Co2+ solutions and the reaction was then left to reach equilibrium, it was found that the absorption spectra remain practically unchanged, indicating that salen did not complex these cations, while the addition of Fe2+ led to a slight shift to 423 nm with higher absorbance. As a result, there was expected the interaction between ionophore and Fe2+. The linear working concentration range determined by plotting the absorbance against the logarithm of Fe(II) concentration was found in the range of 10-4 to 10-2 M as presented in Figure 5 with the limit of detection of 1.19 × 10-4 M. However, the membrane compositions must be further varied to obtain the better linear range and also detection limit. In addition, other membrane characteristics, for example, working pH range, reversibility, lifetime of optical sensor, as well as the optimized membrane composition will be further studied in order to find the best performance sensor which could be reusably applied for the determination of target ion in real samples. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 235 Abs (423 nm) 0.2 y = 0.0317x + 0.1908 R² = 0.9936 0.15 0.1 0.05 0 -8 -7 -6 -5 -4 -3 -2 -1 log [Fe(II)] Figure 5. Response of a polymeric optical film in various concentrations of Fe(II) at 423 nm. 4. Conclusions N,N'-Ethylenebis(salicylimine) or Salen ligand showed good sensitivity and selectivity as ionselective ionophore due to its stability in polymeric optical membrane. This compound tended to be selective to Fe(II) ion, considering from the preliminary results. The absorption spectra increased gradually with increasing Fe(II) concentration, suggesting that salen could bind this ion using N and O donor atoms along with the suitable cavity size. The presence of cation exchanger could also enhance the sensing property of proposed optical film. Moreover, the response time of prepared membrane slides was 5 minutes to reach the equilibrium of complexation between our ionophore and target ion with the working concentration range of 10-4 to 10-2 M of Fe(II) ion and the limit of detection of 1.19 × 10-4 M. The membrane composition, especially the amounts of salen ionophore and cation exchanger should be optimized to improve the membrane performance. Other important characteristics of the proposed optodes must also be monitored in order to find the best performance sensor for further applications. [4] Badr, I.H.A. and Meyerhoff, M.E., 2005, Highly selective single-use fluoride ion optical sensor based on aluminum(III)-salen complex in thin polymeric film, Analytica Chimica Acta, 553, 169-176. [5] Badr, I.H.A., 2006, Potentiometric anion selectivity of polymer-membrane electrodes based on cobalt, chromium, and aluminum salens, Analytica Chimica Acta, 570, 176-185. [6] Gorski, Ł., Matusevich, A., Parzuchowski, P., Łuciukb, I. and Malinowska, E., 2010, Fluoride-selective polymeric membrane electrodes based on Zr(IV)- and Al(III)-salen ionophores of various structures, Analytica Chimica Acta, 665, 39-46. [7] Rezayi, M., Ahmadzadeh, S., Kassim, A. and Heng, L.Y., 2011, Thermodynamic Studies of Complex Formation Between Co(SALEN) Ionophore with Chromate (II) Ions in AN-H2O Binary Solutions by The Conductometric Method, International Journal of Electrochemical Science, 6, 6350-6359. [8] Diehl, H. and Hach, C.C., 1950, Bis(N,N'Disalicylalethylenediamine)-μ-Aquodicobalt(II), Inorganic Syntheses, 3, 196-201. Acknowledgements This work was supported in part from Faculty of Science, Maejo University, and National Science and Technology Development Agency (NSTDA), Thailand. . References [1] Lobnik, A., Turel, M. and Urek, Š.K., 2012, Optical Chemical Sensors:Design and Applications, Advances in Chemical Sensors, InTech, Rijeka, Croatia. [2] Bakker, E., Bühlmann, P. and Pretsch, E., 1997, Carrier-Based Ion-Selective Electrodes and Bulk Optodes. 1. General Characteristics, Chemical Reviews, 97, 3083-3132. [3] G´orski, Ł. , Saniewska, A., Parzuchowski, P., Meyerhoff, M.E. and Malinowska, E., 2005, Zirconium(IV)-salophens as fluoride-selective ionophores in polymeric membrane electrodes, Analytica Chimica Acta , 551, 37-44. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 236 PREPARATION OF PROTIC IONIC LIQUID/POLYVINYLPYRROLIDONE COMPOSITES WITH ENHANCED HYDROPHOBICITY Nuttakarn Moolthong, Natkritta Maipul and Phawit Putprasert* Department of Chemistry, Faculty of Science and Technology, Thammasat University, Pathumthani, 12120, Thailand *E-mail: [email protected], Tel. +66 2564 4440, Fax. +66 2564 4483 Abstract: Hydrophobic surfaces have recently gained attentions from several industries due to various potential applications. To overcome the static charge accumulation, such surfaces with good electrical conductivity are needed. The introduction of ionic liquids with a certain degree of hydrophobicity into polymer provides the desired conductivity. In this report, several protic ionic liquids (PILs) have been prepared from reactions between Brønsted acids and Brønsted bases. Simple and low cost neutralization reactions between these organic acids and bases produced PILs with high conductivity (up to 3.36 mS cm-1) at room temperature. The obtained PILs were characterized by 1H-NMR spectroscopy and their thermal stabilities were studied by thermogravimetric analysis. Several PILs including triethylammonium benzoate with potentially high hydrophobicity were then selected for the composite fabrication. Polymer composites of polyvinylpyrrolidone (PVP) with enhanced hydrophobicity have been prepared with various amounts of the selected PILs. Water contact angles of PVP/PIL composites were measured to evaluate the enhanced hydrophobicity. The surface of PVP without PIL shows poor hydrophobicity with the water contact angle of 65.9°. Upon the addition of PILs, the PVP composite with 20% of triethylammonium benzoate exhibits the largest water contact angle of 117.4°. 1. Introduction In recent years, a hydrophobic surface has become a growing interest for many industries. Two major factors that control such property are the chemical composition and the geometrical microstructure. Its potential applications include self-cleaning surface, stain-resisting fabrics, and antifouling coatings, for example [1]. However, such hydrophobic surface often leads to static charge accumulation, which can cause fire or explosion under dry conditions. It has been known that conductive materials are used to dissipate static charge. To prevent potential dangers of static charge accumulation, the hydrophobic surface, therefore, must be conductive. Ionic liquids are a group of ionic compounds in a liquid state around room temperature, unlike common ionic compounds with high melting points [2-3]. Ionic liquids have gained attention in past few decades with many potential applications. Protic ionic liquids (PILs) are a subset of ionic liquids. PILs can be easily produced via a combination reaction between a Brønsted acid and a Brønsted base, involving a proton transfer from the acid to the base [4-5]. Similar to other ionic liquids, PILs also show high conductivity and high thermal stability. There are many reports which ionic liquids, both protic and aprotic, have been used to prepare conductive polymer composites for various applications such as conductive membrane for dyesensitized solar cells (DSSCs) or proton exchange membrane fuel cells (PEMFCs) [6-10]. In this report, PILs were utilized not only as conducting agent, but also as hydrophobicity enhancer for the polymer composites. Even though PILs are composed of ions only, these ions are organic compounds. Due to its organic nature, the PILs are hydrophobic to some extent and can enhance the hydrophobicity of the polymer composites which can be evaluated using the water contact angle (WCA) measurement [11]. 2. Materials and Methods 2.1 General Setting All chemicals and solvents were standard analytical grade and used without further purification. 2.2 Synthesis and characterization of PILs The synthesis PILs was adapted from literatures [12-13]. In a typical synthesis of PIL, a Brønsted base (0.2 mol) was added to a round bottom flask and was cooled in an ice bath. A Brønsted acid (0.2 mol) was added dropwise while stirring. The reaction was allowed to warm up to room temperature and was stirred for 12 hours to obtain the desired PIL. The remaining starting materials were removed under reduced pressure for one hour by using rotary evaporator. When benzoic acid was used as a Brønsted acid, it was dissolved in minimal amount of diethyl ether before the solution was added to the Brønsted base. Diethyl ether and any remaining starting materials were then removed under reduced pressure using a similar procedure described above. 1 H-NMR spectra were obtained using a Bruker DPX-400, CDCl3 as a solvent and TMS as internal standard. Ionic conductivities of PILs were measured by conductometer (WTW, Cond 340i). Thermal gravimetric analysis (TGA) was conducted on a Perkin Elmer TGA7 under N2 flow with a heating rate of 10 °C/min. 2.3 Preparation and characterization of PVP/PIL composites The polymer composites were prepared with 5%, 10%, and 20% by weight of PIL. In a typical preparation, 5 g of PVP and an appropriate amount of Pure and Applied Chemistry International Conference 2015 (PACCON2015) 237 PIL (0.25, 0.5, and 1.0 g) were dissolved in 20 mL ethanol. After stirring for two hours, the mixture was cast on a Teflon container. The solvent was allowed to evaporate overnight and the composite polymer was peeled off for characterization. TGA was conducted on a Perkin Elmer TGA7 under N2 flow with a heating rate of 10 °C/min. Water contact angles (WCAs) were measured on a ramé-hart Model 220 Standard Contact Angle Goniometer. 3. Results and Discussion PILs were obtained in good yields and were characterized by 1H-NMR spectroscopy. Because the structures of PILs are almost similar to their corresponding starting materials, the chemical shifts of PILs’ protons are also almost identical to those of the starting acids and bases. The features from the NMR spectra that can distinguish the PILs are the presence of peaks of ammonium proton, which could be observed as a broad singlet in the downfield region, usually around 9–10 ppm. The NH chemical shifts of the obtained PILs are listed in Table 1. The conductivities of PILs were measured using a conductometer. The results are shown in Table 1. Triethylammonium formate shows the highest conductivity of 3.36 mS cm-1 and N,Ndimethylanilinium benzoate shows the lowest conductivity of 0.0001 mS cm-1. The size of the ions of PILs probably affects the conductivity of PILs since smaller size implies greater ion mobility and consequently better conductivity. The small size of ions in triethylammonium formate, therefore, results in high conductivity. On the other hand, PILs containing larger ions such as benzoate or p-toluenesulfonate show lower conductivity. From TGA analysis, the temperatures of decomposition (Td) of PILs were presented in table 1. From the result, PILs with formate and benzoate as anions started to decompose at around 70 and 110 °C, respectively. This can probably be attributed to the molecular weight of PILs. Specifically, thermal stability of PILs increases as the molecular weight increases, making. PIL with p-toluenesulfonate anions the most thermally stable (Td > 279 °C). Table 1: Percent yields, ionic conductivities, and temperature of decomposition (Td) of obtained PILs Yield (%) Conductivity (mS cm-1) Td (°C) Triethylammonium formate 31.26 3.36 70 NH chemical shift (ppm) 10.50 Triethylammonium benzoate 82.46 0.10 150 9.56 Triethylammonium p-toluenesulfonate 64.63 0.18 321 9.95 N,N-dimethylanilinium formate 27.53 0.15 70 10.00 N,N-dimethylanilinium benzoate 97.22 0.0001 110 8.85 N,N-dimethylanilinium p-toluenesulfonate 61.09 0.27 279 10.00 PIL Two of the obtained PILs, triethylammonium benzoate and N,N-dimethylanilinium formate, were selected to prepare polymer composites with PVP. The benzene ring in the benzoate anion and the benzene ring in aniline were expected to increase the hydrophobicity of the polymer composites. The resulting PVP/PIL composites are transparent and uniform film with a thickness of about 1 mm. Figure 1 shows photographs taken during WCA measurements of PVP and PVP/PIL composites with various amounts of triethylammonium benzoate. PVP exhibits WCA of 65.9° and is regarded as hydrophilic. Addition of triethylammonium benzoate increases the WCA of the PVP/PIL composites significantly as clearly observed in Figure 1 (b-d). The higher loading of triethylammonium benzoate also increases the hydrophobicity of the PVP/PILs composite. In fact, the PVP/PIL composite with 20% triethylammonium benzoate exhibits the highest WCA of 117.4°. However, N,N-dimethylanilinium formate showed only slight improvement on the hydrophobicity of the PVP composites. With 20% N,N-dimethylanilinium formate, the PVP/PIL composites exhibit the WCA of 79.0°, only 9.6° greater than pure PVP film. Figure 1. Photographs of WCA measurements of (a) PVP and (b-d) PVP with 5%, 10% and 20% triethylammonium benzoate, respectively. Pure and Applied Chemistry International Conference 2015 (PACCON2015) 238 WCAs of all PVP composites are presented in table 2. In addition, PVP/PIL composites are thermally stable. Table 2 shows the initial decomposition temperatures (IDTs) of PVP/PIL composites. Compared to pure PVP, the PVP/PIL composites generally have lower IDT because PILs decompose at lower temperatures than PVP. Thus higher loadings of PILs slightly lower the IDT of PVP/PIL composites as shown in table 2. However, even with 20% loading of PILs, the PVP/PIL composites still exhibit high thermal stability (>200 °C). Table 2: Water contact angles (WCAs) and initial decomposition temperatures (IDTs) of PVP/PIL composites PVP only WCA (°) 65.9 IDT (°C) 350 5% 108.7 260 10% 111.4 250 20% 117.4 215 5% 69.4 270 10% 75.8 265 20% 79.0 231 PIL % PIL triethylammonium benzoate N,Ndimethylaniline formate [5] Angell, C. A., Byrne, N. and Belieres, J-P., 2007, Acc. Chem. Res., 40, 1228 [6] Fuller, J., Breda, A. C. and Carlin, R.T., 1997, J. Electrochem. Soc., 144, L67–69. [7] Wang, P., Zakeeruddin, S. M., Exnar, I. and Gratzel, M., 2002, Chem Commun., 2972–2973. [8] Bansal, D., Cassel, F., Croce, F., Hendrickson, M,, Plichta, E. and Salomon, M., 2005, J. Phys. Chem. B., 109, 4492. [9] Yeon, S. H., Kim, K. S., Choi, S., Cha, J. H. and Lee, H., 2005, J. Phys. Chem. B., 109, 17928–17935. [10] Fukushima, T., Asaka, K,, Kosaka, A. and Aida, T., 2005, Angew. Chem. Int. Ed., 44, 2410–2413. [11] Lu, X., Zhou, J., Zhou, Y., Qiu, Y. and Li, J., 2008, Chem. Mater., 20, 3420. [12] Anouti, M., Caillon-Caravanier, M., Dridi, Y., Galiano, H. and Lemordant, D., 2008, J. Phys. Chem. B., 112, 13335-13343. [13] Anouti, M., Caillon-Caravanier, M., Le Floch, C. and Lemordant, D., 2008, J. Phys. Chem. B., 112, 94069411. 4. Conclusions In summary, we have utilized simple neutralization reactions between Brønsted acids and Brønsted bases to produce several protic ionic liquids in good yields. Some of the obtained PILs exhibit high conductivity and high thermal stability. Triethylammonium benzoate and N,N-dimethylanilinium formate were selected to prepare composites with PVP. The results showed that the PVP/PIL composites with 20% triethylammonium benzoate demonstrated the largest water contact angle of 117.4°. All PVP/PIL composites also exhibited high thermal stability. Acknowledgements We would like to thank Thailand Research Fund (MRG5480199) and Department of Chemistry, Faculty of Science and Technology, Thammasat University for financial support. References [1] Zhu, Y., Zhang, C., Zheng, M., Huang, B., Feng, L. and Jiang, L., 2006, Adv. Funct. Mater., 16, 568-574. [2] Welton, T., 1999, Chem. Rev., 99, 2071-2083. [3] Wasserscheid, P. and Keim, W., 2000, Angew. Chem. Int. Ed., 39, 3772-3789. [4] Greaves, T. and Drummond, C. 2008, Chem. Rev., 108, 206-237. Pure and Applied Chemistry International Conference 2015 (PACCON2015)