Alonso_Pisa2005

Transcription

Alonso_Pisa2005

GRUPO DE ESPECTROSCOPIA MOLECULAR
Universidad de Valladolid
DETECTING HYDROGEN BONDING
USING MBMB-FTMW
José L.Alonso
Spain
(XIII century 1293)
Spain
(XIII century 1293)
Pr. JUAN C. LÓPEZ
Catedrático Química-Física
Pr. ALBERTO LESARRI
Pr. Titular Química-Física
D. SANTIAGO MATA
Técnico de Laboratorio
Lcdo. EMILIO COCINERO
Becario FPI
Grupo de Espectroscopia
Molecular
Dra. RAQUEL SANCHEZ
Becaria FPI
Dra. M. EUGENIA SANZ
Invetigadora Ramón y Cajal
Pr. JOSE L. ALONSO
Catedrático Química-Física
Lcdo.. PABLO VILANUEVA Ph. D. Student
Lcda. VANESSA VAQUERO Ph. D. Student
Lcda. VANESA CORTIJO Ph. D. Student
Lcda. ISABEL PEÑA Ph. D. Student
Frequency Domain:
Domain:
Stark Modulation Microwave Spectroscopy
Microwave Spectroscopy:
Spectroscopy:
Historical Overview
1950:
1950: After World War II the
components of Radar systems
were used to establish
MW and MMW
E.B.
E.B. Wilson (Harvard
(Harvard )
C.H.Townes (U. California)
A.L.Schawlow (Stanford)
Stanford)
W.Gordy (Duke University)
University)
Dra. SUSANA BLANCO
Asociada Química-Física
Computer Controled Spectrometer
8-50 GHz
Valladolid 1985
Laser-ablation
MB-FTMW
Solid
compounds
MBFT-MW
Jets
Flygare
Flygare
FT-MW
Timedomain
Townes, Wilson, Gordy
Stark modulation
Cleeton & Willians
Video mod.
NH3
hν
MW Source
MW &
MMW
Spectroscopy
Detector
Stark Cell
ν
Ι
Stark Modulation
t
M=0
M=2
M=1
ν
Experimental Information by Microwave
Spectrocospy
Rotational Spectra in the
MW and MMW region
Rotational
Constants
Centrifugal
Distortion
Stark Effect
Hyperfine
Structure
Conformation
and Structure
Force Field
Large Amplitud
Motions
Electric
Dipole Moments
Components
Charge distribution
Internal Rotation
1
Spectroscopy:
FTMW + Supersonic Jets (MB) = MB-FTMW
Historical Overview
1974:
1974: The availability of digital circuits
transfer the timetime-domain spectroscopy
to MW. (Static
(Static gas samples)
samples)
Fourier Transform Microwave
Spectroscopy FTMW
W.H.
W.H. Flygare (Illinois. USA).
Flygare
H.Dreizler (Kiel.Germany)
Kiel.Germany)
1979:
1979: Flygare promoted the field by combination of supersonic expansions
(MolecularMBMolecular-Beam,
Beam, MB)
MB) with FTMW Spectroscopy
MB-FTMW
Laser-ablation
MB-FTMW
* Improved resolution and sensitivity:
sensitivity: Frequency accuracy ~ 2KHz
Resolution ~ 7KHz
Solid
compounds
MBFT-MW
generador
pulsos
FT-MW
Timedomain
10 MHz
Supersonic
Jets
10 MHz
160 MHz
Stark modulation
Cleeton & Willians
Fabry-Pérot Cavity
MW &
MMW
Spectroscopy
Video mod.
FTMW spectrometer
ordenador
PC
Frquency domain
NH3
Control
pulso
molecular
ν - 160
MHz
GP-IB I/O
D/A
A/D
A/D
New horizons in determining molecular properties
Characterizing molecular complexes.
complexes.
Supersonic Jets : Properties
Supersonic Jets
Supersonic Jet:
Barril de Choque
Límite de la
expansión
Adiabatic expansion of a gas mixture through small (0.5 mm)
mm) nozzle
into a high vacuum
Disco de Mach
High vacuum
Pr ∼ 10-6-10-8 bar
Carrier gas
(He, Ne,
Ne, Ar,..)
Ar,..)
zone of
silence
p0, T0
pr, Tr
Sample
(~1%)
3.0
Stagnation pressure
f ( v x ) / 10 − 3 m −1s P ∼ 1-5 bar
0
2.5
Ar (300 K)
Binary
collisions
vx = 0
2.0
nozzle
60 f ( v ) / 10−3 m −1s
x
∅ = 0.1-1 mm
50
40
1.5
30
1.0
20
0.5
0.0
-1000
10
v x / m s −1
-500
0
500
three body
collisions
AB
G
Strong
RoRo-vib cooling
0
-1000
1000
M>>1
Vf
(Tt < 1 K)
-500
0
v x / m s −1
500
1000
A
B
G
Molecular Complexes
in collisionless expansion
HOW A MB-FTMW SPECTROMETER WORKS?
MB-FTMW (5-18.5 GHz) Valladolid 1997
→ SEQUENCE OF OPERATION
0.1-1 ms
Injection
system
1. Formation of a gas pulse :
Supersonic Expansion
Molecular
pulse
0.5 ms
2. Microwave Pulse :
Polarization of
Molecules
FTMW
Spectrometer
0.1-2 µs
Microwave
pulse
3. Molecular Emission : free induction
decay+ Dissipation of the polarization energy
FT
4. Detection
15-60 µs
Molecular
Emission
Detection
System
Frequency
Domain
Frequency
Domain
ALONSO et al. Chem.
Chem. Phys.,
Phys., 218,
218, 267 (1997)
2
Detecting Hydrogen Bonding using MBMB-FTMW
Intermolecular Complexes : AA-H ··· B
Two equivalent nonnon-bonding electron pairs at B:
Intramolecular
Intramolecular
Hydrogen Bonding
Intermolecular
Intermolecular
Hydrogen Bonding
HX
HX
O
Intermolecular
Complexes
•Axial / Equatorial
Hydrogen bonds
• C-H···O,
H···O, CC-H···F,
H···F,
Micro
solvation
Water clusters:
Formamide··
(H2O)n ·
Biomolecules
Neurotransmitters:
Neurotransmitters:
Ephedrine…
Ephedrine…
Amino Acids
Two nonnon-equivalent electron pairs at B :
HX
Laser ablation of
solids compounds
LALA-MBFTMW:
O
HX
Two conformers
O
Valine,Serine,
Valine,Serine, Cysteine,
Cysteine,
GABA, Glycine··· Water
Uracil, Thymine, Cytosine
• C-H⋅⋅⋅π
One conformer
O
HX
O
HX
AXIAL and EQUATORIAL HYDROGEN BONDS
Cl
The observation of both axial and
equatorial conformers in the fourfourmembered rings
axial
equatorial
H
O
.. O
H
Cl
existence of a ringring-puckering largelarge-amplitud
motion that prevails after the hydrogen bond
formation, emerging two nonequivalent
binding sites which result in different axial
and equatorial conformers.
600
500
-2
-1
0
400
1
2
3
V(X) /cm
-1
X
First experimetal observation of axial and equatorial hydrogen bonds
the non-bonding electron pairs at B(O,S) are non equivalents
as a consequence of the chair conformation of the ring in the
six-membered rings
300
ecuatorial
200
axial
100
0
-3
-2
-1
0
1
2
3
X
-3
Alonso et al. Angew. Chem. Int. Ed., 1999, 38, 1772
-2
-1
0
1
2
3
X
Chem.Phys.Chem.,2, 114, 2001.
WEAK HYDROGEN BONDS: C-H···O , C-H···F
Two bifurcated hydrogen bonds : CC-H····O
····O and CC-H····F
····F
θ = 14.1(8)º
axial
3.20 Å
2.28(2) Å
ϕ = 92.1(10)º
equatorial
OXIRANE
ϕ = 91.1(17)º
H
O
H
H
2.26(6) Å
3.26 Å
H
F
DIFLUOROMETHANE
F
θ = 18.4(5)º
SANZ, LESARRI, LOPEZ, ALONSO,
Angew.
Angew. Chem.
Chem., 40,
40, 935 (2001)
ChemPhysChem 2004
3
WEAK HYDROGEN BONDS: C-H···O , C-H···F
WEAK HYDROGEN BONDS: C-H⋅⋅⋅π
TRIFLUOROMETHANE
*Weak Hydrogen Bond Complex
stabilized by a CH⋅⋅⋅π weak hydrogen
bond. is a symmetric top.
BENZENE··TRIFLUOROMETHANE
symmetric top.
* Both species are characterized by
an almost free rotation of the two
subunits with respect to each other.
The estimated dissociation energy is
8.4 kJ/mol.
OXIRANE
el. Int.
E
1.0
E
A
A
0.8
Three weak hydrogen bonds, one C-H⋅⋅⋅O and
two C-H⋅⋅⋅F-H, establish the global minimum
configuration of the oxirane···trifluoromethane
adduct. The trifluoromethyl group can rotate
almost freely (V3 = 0.55 kJ/mol) around its C3
symmetry axes.
0.6
0.4
0.2
0.0
6678.25
6678.50
6678.75
6679.00
6679.25
Alonso et al.JACS, 2004
MICROSOLVATION:
The formamide ···(H2O)n
We have analyzed the rotational spectra of formamide-(H2O)n clusters:
2) To search for evidences of cooperative effects such as polarization enhanced or
resonance assisted hydrogen bonding
H
O
H
N
H
1:1c At the NH site the water acts as an acceptor through the anti-hydrogen of
the amino group.
1:2a Closed Cyclic structure with two water molecules establishing three hydrogen
bonds.
O
O
H
H
H
C
H
interactions of water with the peptide functional group
H
H
C
H
H
O
O
N
1:1b At the CO site the water acts as a proton donor bonded through the
lone-pair of the oxygen atom in the carbonyl group.
H
H
H
(n=1,2) clusters
1:1a The most stable conformer of the formamide-H2O complex (), is stabilized by
two hydrogen bonds O-H···O=C and N-H···O with water closing a cycle structure.
1) To characterize the different 1:1 and most stable 1:2 conformers.
mimics the peptide group
MICROSOLVATION: The formamide···(H2O)n
(n=1,2) clusters
O
C
N
H
shortening of HB lengths
r(Cr(C-N) decrease
1:1a
Formamide ···H2O
1:1b
1:1c
Formamide ···H2O
1:1a
1:2a
1:1b
3 ← 2
1
0
2 ← 1
1 ← 0
F’ ← F’’
1 ← 1
15510.5
15511.0
A / MHz a
2 ← 2
15511.5
-13COH
NH2
···(H2O)
15 NH -COH
2
···(H 2O)
NDsHa-COH
···(H 2O)
NH sD a-COH
···(H2O)
NH 2-COH
···(H218O)
NH2-COH
···(D bHcO)
NH 2-COH
···(HbD cO)
10925.1667(27)
10844.4309(24)
10419.4158(49)
11221.9584(35)
11191.9592(21)
11140.3424(36)
2682.97837(68)
2684
C / MHz
2433.84992(64)
2433.84900(63)
2438
∆J / kHz
7.6202(147)
µa- and µb-type spectra
14N quadrupole HFS
Tunneling Splittings (kHz)
11227.9330(23)
11224.4801(33)
4586.9623(16)
4528.4531(13)
4565.9951(10)
4588.54771(69)
4514.1426(14)
4286.04140(99)
4287.0567(14)
4520.03865(10)
∆JK / kHz
-0.29706( 38)
B/ MHz
C/ MHz
3258.8277(12)
3228.9331(11)
3222.31874(95)
3226.77112(64)
3151.8641(13)
3103.50898(94)
3105.3851(14)
3218.02144(10)
∆K / kHz
[0.0]e
∆ / u Å2
-0.10814(41)
-0.10973(41)
-0.10439(39)
-0.12118(37)
-0.11529(44)
-0.10644(44)
-0.29761(44)
-0.12682(40)
δJ / kHz
1.3691 (133)
∆J / kHz
7.844(70)
[7.844]c
[7.844]
[7.844]
[7.844]
[7.844]
[7.844]
[7.844]
δK / kHz
[0.0]
∆JK/ kHz
24.24(48)
[24.24]
[24.24]
[24.24]
[24.24]
[24.24]
[24.24]
[24.24]
∆K / kHz
[0.0]
[0.0]
[0.0]
[0.0]
[0.0]
[0.0]
[0.0]
[0.0]
2.728(58)
[2.728]
[2.728]
[2.728]
[2.728]
[2.728]
[2.728]
[2.728]
δK / kHz
[0.0]
[0.0]
[0.0]
[0.0]
[0.0]
[0.0]
[0.0]
[0.0]
χaa / MHz
1.8625(22)
χbb / MHz
1.7393(39)
χcc / MHz
-3.6018(39)
1.3321(37)
1.3377(69)
1.3571(36)
1.3653(73)
1.3391(52)
1.3457(31)
1.3493(64)
σ / kHz
3.3
χ bb/ MHz
2.0371(20)
2.0334(64)
2.0381(20)
2.0485(41)
2.0271(28)
2.0333(17)
2.0413(26)
Ν
66
χ cc/ MHz
-3.3693(96)
-3.371(26)
-3.3951(96)
-3.415(20)
-3.366(14)
-3.3791(81)
-3.391(14)
χ aa/ MHz
σ / kHz
4.9
2.6
3.9
8.2
5.7
6.6
6.0
N
15
5
21
21
21
21
21
25970
2682.97653(65)
A/ MHz
δJ / kHz
MP2/6311++G(d,p)
B / MHz
15512.0
ν / MHz
Parenta
26170.8(61)d
0
1
0
F’ ←
F’’
2←1
1
3←
2
0
1
15723.5
4←
3
15724.0
ν / MHz
4
Formamide ···H2O
a
2083.6104(127)c
B / MHz
35288
2073
2084.6949(126)
1949.3157(126)
C / MHz
1949.7631(122)
A/ MHz a
1979
∆ / u Å2
χaa / MHz
1.5068(47)
χbb / MHz
1.23(34)
χcc / MHz
-2.73(34)
µa- and µb-type spectra
14N quadrupole HFS
Tunneling Splittings (MHz)
σ / kHz
2.3
Ν
26
1:2 a
MP2/6311++G(d,p)
b
[35288]b
A / MHz a
Formamide···(H2O)2
1:1c
3←
2
2
←
11 2
← ←
0 2
F’ ←
F’’
1←
1 8065.0
8064.5
8065.5
8066.0
3
MH
z
2
←
1 2
1 ←
← 2
0
1←
1
8067.5
8068.0
ν / MHz
Formamide···(H2O)2
NH2-13COH
···(H2O)2
4384.3559(50)b
4384.34925(250)
8068.5
8069.0
-COH
2
···(H2O)2
NDsHa-COH
···(H2O)2
4334.6691(20)
4321.9095(33)
B/ MHz
2630.4957(158)
2590.06990(52)
2611.20693(44)
2630.42759(305)
C/ MHz
1651.1140(125)
1635.09880(34)
1636.47057(26)
1642.26244(72)
∆J / kHz
[2.08]
2.08(68)
[2.08]
[2.08]
∆JK/ kHz
16.3(3.8)
[16.3]
[16.3]
∆K / kHz
[0.0]c
[0.0]
[0.0]
[0.0]
δJ / kHz
0.565(152)
[0.565]
[0.565]
[0.565]
[18.1]
[18.1]
δK / kHz
3
F’ ← ←
F’’ 2
15NH
Parent
18.1(5.7)
[16.3]
[18.1]
χaa/ MHz
1.0739(34)
1.0608(69)
1.0467(168)
χbb/ MHz
2.0063(45)
2.0220(101)
2.0141(208)
χcc/ MHz
-3.0802(45)
-3.0828(101)
σ / kHz
3.9
4.0
2.0
-3.0607(208)
5.1
N
37
20
8
13
8069.5
ν / MHz
Structures : Formamide
1:2 a
3
←
2
F’ ←
F’’
1
2← ←
1 0
1←1
8 2 52 .5
8 25 3 .0
8 25 3 .5
2
←
2
rs
8 25 4 .0
ν / MH z
NH2-COH
···(H218Ow)(H2O)
NH2-COH
···(DbHcO)(H2O)
NH2-COH
···(HbDcO)(H2O)
NH2-COH
···(H2O)(H218Ov)
NH2-COH
···(H2O)(DdHeO)
NH2-COH
···(H2O)(HdDeO)
A/ MHza
4257.87728(396) b
4267.05691(370)
4380.5341(46)
4258.42155(312)
4313.55882(347)
4230.04111(313)
B/ MHz
2550.81170(119)
2554.07174(293)
2582.15945(359)
2558.17803(94)
2625.27494(238)
2575.60939(225)
C/ MHz
1601.76873(42)
1609.03594(50)
1631.64517(66)
1604.74185(33)
1639.01599(51)
1611.42773(41)
∆J / kHz
[2.08]c
[2.08]
[2.08]
[2.08]
[2.08]
[2.08]
∆JK/ kHz
[16.3]
[16.3]
[16.3]
[16.3]
[16.3]
[16.3]
∆K / kHz
[0.0]
[0.0]
[0.0]
[0.0]
[0.0]
[0.0]
δJ / kHz
[0.565]
[0.565]
[0.565]
[0.565]
[0.565]
[0.565]
δK / kHz
[18.1]
[18.1]
[18.1]
[18.1]
[18.1]
[18.1]
χa/ MHz
1.0493(91)
0.9975(193)
1.0447(234)
1.0754(75)
1.0717(181)
1.0575(123)
χb/ MHz
2.0142(147)
2.0295(238)
2.0334(290)
2.0009(121)
2.0286(225)
2.0108(177)
χc/ MHz
-3.0634(147)
-3.0269(238)
-3.0782(290)
-3.0763(121)
-3.1002(225)
-3.0684(177)
σ / kHz
6.4
5.9
7.2
5.2
5.5
5.0
N
21
17
16
21
16
18
Hs 118.2(9)º
121.4(6)º
N
C
Ha
1.34(2) Å
r(C-N)/ Å
1.343(21)
r(C-Hs)/ Å
1.0020(84)
r(C-Ha)/ Å
0.9907(72)
∠(C-N-Hs)/ º
118.23(86)
∠(C-N-Ha)/ º
120.4(1.2)
∠(Ha-N-Hs)/ º
121.37(64)
Structures : Formamide 1:2a
Structures : Formamide 1:1a
rs
r(C-N)/ Å
rs
Hb
Ow
2.123(9) Å
r(C-N)/ Å
150(2)º
Hc
1.875(3) Å
107.6(6)º
Hs
138.9(8)º
N
119.4(6)º
Ha
1.34(2) Å
C
O
1.341(15)
r(C-Hs)/ Å
0.9321(93)
r(C-Ha)/ Å
0.9753(79)
r(Ow-Hb)/ Å
0.919(25)
r(Ow-Hc)/ Å
1.022(11)
r(Ow ··· Hs)/ Å
2.1234(91)
r(O ··· Hc)/ Å
1.8745(33)
∠(C-N-Hs)/ º
119.56(58)
∠(C-N-Ha)/ º
120.6(1.2)
∠(Ha-N-Hs)/ º
119.37(64)
∠(Hb-Ow-Hc)/ º
106.1(2.9)
∠(N-Hs···Ow)/ º
138.87(75)
∠(C-O···Hc)/ º
107.56(56)
∠(Hs···Ow-Hc)/ º
77.34(56)
∠(Hb-Ow-Hc···Hs)/ º
150.4(2.4)
1.69(1) Å
-144(3)º
Hc
Hb
He
Ov
100.2(4)º
Ow
115(5)º
Hd
1.759(4) Å
97.3(3)º
1.79(2) Å
Hs
131(2)º
N
Ha
1.31(7) Å
C
O
1.307(72)
r(C-Hs)/ Å
1.126(21)
r(Ow-Hb)/ Å
0.970(30)
r(Ow-Hc)/ Å
1.109(10)
r(Ov-He)/ Å
0.961(26)
r(Ov-Hd)/ Å
1.0243(51)
r(Ow ··· Hs)/ Å
1.792(20)
r(Ov ··· Hc)/ Å
1.6852(98)
r(O ··· Hd)/ Å
1.7590(40)
∠(C-N-Hs)/ º
121.2(1.9)
∠(Hb-Ow-Hc)/ º
108.7(2.2)
∠(He-Ov-Hd)/ º
106.8(2.4)
∠(N-Hs···Ow)/ º
171.2(4.1)
∠(Hs···Ow-Hc)/ º
97.26(25)
∠(Ow-Hc···Ov)/ º
157.5(2.2)
∠(Hc···Ov-Hd)/ º
100.15(42)
∠(C-O···Hd)/ º
130.7(2.1)
∠(Hb-Ow-Hc···Hs)/ º
-144.4(3.2)
∠(He-Ov-Hd···Hs)/ º
114.7(4.5)
5
NEUROTRANSMITTERS
Cooperative Effects
H
H
2.12
H
N
O
H
H
H
C
H
1.34(2) Å
H
H
H
1.87
O
1.69
O
O
H
1.79
O
H
H
H
C
N
Molecules which mediate the
connections between nerve cells
belong to the family of
neurotransmitter. Many share a
common structural motif
Ethylamine side chain
* No evidences resonance assisted hydrogen bonding
Ethanolamine side chain
C
N
1.34(2) Å
1.76
O
H
1.31(7) Å
r(Cr(C-N) decrease
* Evidences of polarization enhanced hydrogen bonding
shortening of HB lengths
EPHEDRINE
Ephedrine: Lower-energy Conformers
AG(b)
AG(a)
Is representative of a wide family of
neurotransmitters comprising an ethanolamine
side chain attached to an aromatic ring.
Molecular Conformation plays a crucial role
for the understanding of the biological function
O-H···N
( 0 cm-1 )
O-H···N
( 473 cm-1 )
GG(b)
GG(a)
The torsional flexibility of the
side chain results in an unusual
great number of low energy
conformers whose relative
stability is controlled by
intramolecular interactions
involving hydrogen bonding.
O-H···N and N-H···π (256 cm-1 )
( 1108 cm-1 )
EPHEDRINE
MB-FTMW
Spectroscopic
Parameters
Heating Valve
Solid sample
GEM. Valladolid
heating
O-H···N
AG(a)
AG(a)
GG(a)
GG(a)
AG(b)
AG(b)
AB-INITIO EXPERIMENTAL AB-INITIO EXPERIMENTAL AB-INITIO EXPERIMENTAL
A / MHz
2014.4
B / MHz
532.8
529.549500 (41) 597.1
592.448419 (73) 507.2
503.794257 (40)
C / MHz
504.6
500.160014 (41) 579.3
572.416089 (62) 480.0
475.173363 (51)
1998.63822 (35)
1565.7 1568.24526 (49) 2112.1 2115.87705 (59)
χaa / MHz
2.63
2.5347 (13)
2.51
2.447 (12)
2.70
2.564 (17)
χbb / MHz
-3.26
-2.7436 (17)
-2.90
-3.2045 (75)
-4.83
-4.622 (11)
χcc / MHz
0.63
0.2089 (17)
0.39
0.7575 (75)
2.14
2.058 (11)
macor
N-H···π
···π
O-H···N
···N
O-H···N
···N
O-H···N
···N
6
Detecting Hydrogen Bonding using MBMB-FTMW
ORGANIC SOLIDS : ROTATIONAL SPECTRA (?)
¡ Whole series of important organic (biomolecules)
biomolecules)
Intramolecular
Intramolecular
Hydrogen Bonding
Intermolecular
Intermolecular
Hydrogen Bonding
Heating methods
Micro
solvation
Intermolecular
Complexes
•Axial / Equatorial
Hydrogen bonds
• C-H···O,
H···O, CC-H···F,
H···F,
compounds escape from high resolution rotational
spectroscopy due to intrinsically high melting points and
associated very low vapor pressures
Biomolecules
Water clusters:
Formamide··
(H2O)n ·
Neurotransmitters:
Neurotransmitters:
Ephedrine…
Ephedrine…
• C-H⋅⋅⋅π
Amino Acids
Laser ablation of
solids compounds
LALA-MBFTMW:
Valine,Serine,
Valine,Serine, Cysteine,
Cysteine,
GABA, Glycine··· Water
Uracil, Thymine, Cytosine
Laser Ablation
Glycine: m.p. 240ºC
Alanine: m.p. 289ºC
(?)
An effective way of
vaporizing neutral molecules
preventing thermal
decomposition
A
Thermal decomposition
A
A
hν
LALA-MBMB-FTMW
MB -FTMW + Laser Ablation
Laser Ablation
MBMB-FTMW
Spectroscopy
Laser ablation LA is combined with MBMB-FTMW spectroscopy →
LALA-MBMB-FTMW Spectrometer
To allow the structural characterization of the vaporized species in
the adiabatic expansion (gas phase)
phase)
Microwave
antenna
Expansion chamber
Microwave
antenna
FabryFabry-Pérot
resonator
55 cm
Moving
mirror
Fixed
mirror
Dif.
Dif. pump
Rotatory pump
LALA-MBMB-FTMW
LALA-MBMB-FTMW: Ablation nozzle
Valladolid 2005
Ne
Solid
sample
Sample
compartment
Carrier gas
+ precursors
nozzle
Laser
beam
Dif.
Dif. pump
Nd:YAG laser
Rotatory pump
solid
7
LA-MB-FTMW : Experimental Sequence
LALA-MBMB-FTMW
1. Each cycle starts with a gas pulse
of Ne or Ar as carrier gas ⇒
Valladolid 2005
resonator
Fabry-Pérot
gas pulse
FT-MW
SPECTROMETER
FABRY-PEROT
RESONATOR
carrier
gasr
Supersonic jet
laser pulse
LASER
Diff.
pump
Rot. pump
Nd:YAG
(532nm)
2. ⇒ followed by a laser pulse
generating the ablations products
which are seeded in carrier gas
→ Supersonic expansion (jet).
inyector
gas pulse
Espectrometer
FT-MW
Polarization
laser pulse
resonador
Fabry-Pérot
Supersonic jet
Espectrometer
FT-MW
Gas pulse
Carrier
Gas
Polarization
Carrier
gasr
laser pulse
MW
MW pulse
resonator
Fabry-Pérot
molecular emision
MW Pulse
Detection
Diff.
pump
Detección
Detection
diff
pump
Detection
Rot.pump
Rot. pump
3. A very short microwave
induces a macroscopic
FT
Polarization
time domain
Why Amino Acids in the GasGas-Phase ?
The great torsional flexibility of amino acids
results in an unusual great number of stable
conformers of low energy whose relative stability is
contolled by intramolecular interactions.
interactions.
The intrinsic conformational preferences are only
revealed in isolation conditions in the gas phase.
phase.
serine up to
324 predicted
conformers
frecuency domain
Why Amino Acids in the GasGas-Phase ?
Amino Acids in their natural condensed phases
are stabilized as by strong intermolecular
interactions as zwitterions (i.e., a bipolar
ionized form (+H3N-CH(R)CH(R)-COO-) which does not
occur in the polypetide chain →The structural
research of the neutral aminoacids should be
conducted in gas phase where the they present
an unsolvated neutral form HNHN-CH(R)CH(R)-COOH
which represents the best approximation of an
amino acid residue in a polipedtide chain.
8
Why MW Spectroscopy ?
Quantum
Chemistry
Ab initio methods
MP, DFT
Experimental results
Prediction:
Using heating methods:
methods:
Rotational constants
Nuclear quadrupole coupling
Dipole moments
Comparison
LALAMBMB-FTMW
Previous studies
Benchmark
before
Glycine 19781978-
Conformational
Analysis
1980
Molecular Properties:
Nuclear quadrupole coupling
Dipole moments
I
II
2000
Alanine 1993
I
- Two conformers observed
- Structure of conformer II
II
- Two conformers observed
- No Structure
Computational benchmarks : provide accurate structural
information directly comparable to the in vacuo theoretical predictions
Alanine
Amino acids in gasgas-phase
Aliphatic Amino Acids
Imino Acids
BLANCO, LESARRI,
LÓPEZ, ALONSO
JACS., 126, 11675 (2004)
Valine
LESARRI, COCINERO,
LÓPEZ, ALONSO,
Angew.
Angew. Chemie.,43,
Chemie.,43, 605 (2004)
Isoleucine
LESARRI, COCINERO,
LÓPEZ, ALONSO
submitted (2005)
Proline
LESARRI, MATA,COCINERO,
MATA,COCINERO,
BLANCO, LOPEZ, ALONSO,
Angew.
Angew. Chemie.,
Chemie., 41, 4673 (2002)
(4R)-Hydroxiproline
LESARRI, COCINERO,
LOPEZ, ALONSO,
J. Amer.
Amer. Chem.
Chem. Soc.,
Soc., 127, 2572 (2005)
(4S)-Hydroxiproline
Leucine
Alcohol / Tioalcohol side chain
Serine
Two carboxylic groups
Aspartic acid
Cysteine
9
NonNon-coded Amino acids in gasgas-phase
NonNon-coded Amino acids in gasgas-phase
α-Amino acids
N,N-dimetil
glycine
β- and γ-Amino acids
β-Alanine
LESARRI, COCINERO,
LÓPEZ, ALONSO,
ChemPhysChem.
ChemPhysChem. In press (2005)
Sarcosine
β-Aminobutyric
α-Aminobutyric
γ-Aminobutyric
GABA
Phenylglycine
Amino Acids in space ?
Laboratory
SERINE
Radiotelescope
Spectroscopic parameters
Presence in the
interestellar medium:
medium:
¿Origin of life?
life?
8
átomos
9
átomos
10
átomos
CH3C3N
CH3C4H
CH3C5N ?
HCOOCH3
CH3CH2
CN
(CH3)2CO
(CH2OH)2 ?
CH3COOH
(CH3)2O
C7H
CH3CH2
OH
H2NCH2CO2H
Glicina ?
H2C6
HC7N
CH3CH2CHO
CH2OHCHO
C8H
11
átomos
HC9N
12
átomos
13 átomos
C6H6 ?
HC11N
l-HC6H ?
CH2CHCHO ?
The introduction of the ethoxy
group adds two rotors and the
additional donor-acceptor
hydrogen bonding capabilities of
the hydroxy group
136 molecules
(December 2004)
Glycine ?,
Ác.
Ác. Fórmico, ac.
ac. acético, acrilonitrilo,
acrilonitrilo,
Etilenglicol,
Etilenglicol, benceno?
The exploration of the
conformational landscape of serine
by ab initio quantum chemical
calculations
up to 324 predicted
conformations
Gronert et al JACS 117 (1995)
α – Amino Acids
The conformational behavior is conditioned by the
potential formation of 3 different types of intramolecular
hydrogen bonds:
bonds:
➔ Type I: amineamine-toto-carbonyl oxygen (NH···O=C)
NH···O=C)
α – Amino Acids
hydrogen bonds:
bonds:
➔ Type II: N lone pair – Hydroxyl hydrogen (N···HN···H-O)
Conf. I
Conf. I
Conf. II
10
α – Amino Acids
Amino Acids : Side chain orientation
hydrogen bonds:
bonds:
The etoxy group can additionally establish three orientations
of the hydroxy group (a, b, c) for each conformer.
conformer. The
energy ordering of these configurations could depend on the
backbone conformation.
conformation.
➔ Type II: N lone pair – Hydroxyl hydrogen (N···H(N···H-O)
COOH
➔ Type III: H amine group – Hydroxyl oxygen (NH···O
(NH···O--H)
βH
NH2
a
Ia
0 cm-1
Type I
NH···O=C
IIa
592 cm-1
Type II
OH···N
IIIαa
491cm-1
Type IIIα
NH···OH
Type IIIβ
NH···OH
b
H
c
βH
NH2
NH2
H
180º
300º
SERINE : Rotational Spectrum
Ib
691 cm-1
Ic
1002 cm-1
IIb
22 cm-1
IIc
297 cm-1
IIIαc
1328 cm-1
IIIαb
1061 cm-1
IIIβa
OH
H
60º
SERINE : Lower Energy Conformers
COOH
OH
βH
OH
Conf. III
Conf. II
Conf. I
COOH
H
H
H
IIIβb
477cm-1
IIIβc
756cm-1
* a-type R-Branch transitions of an asymmetric rotor were assigned.
* All the transitions are splitted in several components attributable to the
nuclear hyperfine interactions of a single 14N nucleus (I=1).
30,3←20,2
A / MHz
B / MHz
C / MHz
4479.0320 (12)
∆J / kHz
∆JK / kHz
∆K / kHz
δJ / kHz
δK / kHz
0.2006 (61)
1.73 (17)
[0.0]
[0.0]
[0.0]
χaa / MHz
χbb / MHz
χcc/ MHz
-4.3023 (27)
2.82359 (63)
1.4788 (46)
F’ ← F’’=4 ←3
1830.16170 (25)
3←2
1443.79545 (28)
σ / kHz
N
2←1
3←3
9666.0
9667.0
9668.0
ν/ MHz
Η= ΗAR + ΗQ
3.0
53
Watson Semirigid
Rotor
MP4/6-311++G(d,p)
Nuclear Quadrupole
Coupling Term
SERINE
* Another series of a-type R-Branch transitions of an asymmetric rotor were
Ia
IIb
IIc
IIa
IIIβb
assigned.
IIIβc
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
A / MHz
4481
4479.03
3544
3557.20
3656
3638.05
4522
4517.47
3934
3931.75
3519
3510.40
B / MHz
1824
1830.16
2395
2380.37
2378
2387.89
1850
1846.99
2249
2242.76
2331
2321.90
C / MHz
1452
1479
1463.79
1667
1664.53
1580
1584.38
1443.79
1748
1740.92
1518
1519.18
χaa / MHz
- 4.66
- 4.302
- 3.67
- 3.461
- 3.89
- 3.652
- 0.44
- 0.606
- 0.65
- 0.673
- 1.08
-1.048
χbb / MHz
2.92
2.823
2.21
2.079
2.13
2.062
2.05
2.072
- 0.53
- 0.456
- 0.75
-0.563
χcc/ MHz
1.74
1.478
1.44
1.381
1.75
1.590
- 1.61
- 1.466
1.19
1.129
1.82
1.612
∆E / cm-1
0
22
Ia
297
529
477
756
A / MHz
B / MHz
C / MHz
3557.20088 (25)
2380.37208 (40)
1740.92458 (10)
∆J / kHz
∆JK / kHz
∆K / kHz
δJ / kHz
δK / kHz
0.8646 (98)
[0.0]
[0.0]
[0.0]
[0.0]
χaa / MHz
χbb / MHz
χcc/ MHz
-3.4616 (19)
2.07970 (93)
1.3819 (47)
σ / kHz
N
3.3
74
30,3←20,2
F’ ← F’’=4 ←3
3←2
2←1
3←3
1669.0
2←2
11670.0
11671.0
11672.0
11
SERINE
Ia
IIb
IIc
IIa
IIIβb
* Another two series of a-type R-Branch transitions of an asymmetric rotor
IIIβc
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
A / MHz
4481
4479.03
3544
3557.20
3656
3638.05
4522
4517.47
3934
3931.75
3519
3510.40
B / MHz
1824
1830.16
2395
2380.37
2378
2387.89
1850
1846.99
2249
2242.76
2331
2321.90
C / MHz
1452
1443.79
1748
1740.92
1518
1519.18
1479
1463.79
1667
1664.53
1580
1584.38
χaa / MHz
- 4.66
- 4.302
- 3.67
- 3.461
- 3.89
- 3.652
- 0.44
- 0.606
- 0.65
- 0.673
- 1.08
- 1.048
χbb / MHz
2.92
2.823
2.21
2.079
2.13
2.062
2.05
2.072
- 0.53
- 0.456
- 0.75
- 0.563
χcc/ MHz
1.74
1.478
1.44
1.381
1.75
1.590
- 1.61
- 1.466
1.19
1.129
1.82
1.612
∆E / cm-1
0
22
297
529
477
756
IIb
Ia
0 cm-1
were assigned.
30,3←20,2
A / MHz
B / MHz
C / MHz
3638.05784 (38)
2387.89651 (99)
4517.473 (17)
1846.99360 (30)
1519.18716 (36)
1463.79646 (31)
∆J / kHz
∆JK / kHz
∆K / kHz
δJ / kHz
δK / kHz
0.246 (34)
[0.0]
[0.0]
[0.0]
[0.0]
0.242 (10)
[0.0]
[0.0]
[0.0]
[0.0]
χaa / MHz
χbb / MHz
χcc/ MHz
-3.6527 (57)
2.06213 (26)
1.5906 (50)
-0.6066 (55)
2.0723 (82)
-1.466 (30)
σ / kHz
N
2.5
24
F’ ← F’’=4 ←3
2←1
3←2
9947.0
2←1
9948.0
9781.0
3←2
9782.0
ν/ MHz
2.2
24
SERINE
SERINE
Ia
F’ ← F’’=4 ←3
IIb
IIc
IIa
IIIβb
IIIβc
Ia
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
A / MHz
4481
4479.03
3544
3557.20
3656
3638.05
4522
4517.47
3934
3931.75
3519
3510.40
B / MHz
1824
1830.16
2395
2380.37
2378
2387.89
1850
1846.99
2249
2242.76
2331
2321.90
C / MHz
1452
1443.79
1748
1740.92
1518
1519.18
1479
1463.79
1667
1664.53
1580
1584.38
IIb
IIc
IIa
IIIβb
IIIβc
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
4481
4481
4479.03
4479.03
3544
3557.20
3656
3638.05
4522
4522
4517.47
4517.47
3934
3931.75
3519
3510.40
B / MHz
1824
1824
1830.16
1830.16
2395
2380.37
2378
2387.89
1850
1850
1846.99
1846.99
2249
2242.76
2331
2321.90
C / MHz
1452
1452
1443.79
1443.79
1748
1740.92
1518
1519.18
1479
1479
1463.79
1463.79
1667
1664.53
1580
1584.38
A / MHz
χaa / MHz
- 4.66
- 4.302
- 3.67
- 3.461
- 3.89
- 3.652
- 0.44
- 0.606
- 0.65
- 0.673
- 1.08
-1.048
χaa / MHz
--4.66
4.66
--4.302
4.302
- 3.67
- 3.461
- 3.89
- 3.652
--0.44
0.44
--0.606
0.606
- 0.65
- 0.673
- 1.08
-1.048
χbb / MHz
2.92
2.823
2.21
2.079
2.13
2.062
2.05
2.072
- 0.53
- 0.456
- 0.75
-0.563
χbb / MHz
2.92
2.92
2.823
2.823
2.21
2.079
2.13
2.062
2.05
2.05
2.072
2.072
- 0.53
- 0.456
- 0.75
-0.563
χcc/ MHz
1.74
1.478
1.44
1.381
1.75
1.590
- 1.61
- 1.466
1.19
1.129
1.82
1.612
χcc/ MHz
1.74
1.74
1.478
1.478
1.44
1.381
1.75
1.590
--1.61
1.61
--1.466
1.466
1.19
1.129
1.82
1.612
∆E / cm-1
0
∆E / cm-1
0
22
Ia
297
IIb
529
477
756
IIc
22
297
529
IIb
Ia
IIc
477
756
IIa
14N
nuclear quadrupolo coupling constants,which depend on the electronic
environment around the amino nitrogen are extremely sensitive to the
amino group orientation
UNIQUE IDENTIFIER
SERINE
Ia
assigned.
A / MHz
B / MHz
C / MHz
3931.7548 (76)
2242.76701 (70)
1664.53012 (11)
∆J / kHz
∆JK / kHz
∆K / kHz
δJ / kHz
δK / kHz
0.613 (11)
[0.0]
[0.0]
0.245 (11)
[0.0]
χaa / MHz
χbb / MHz
χcc/ MHz
-0.673 (14)
-0.456 (33)
1.129 (84)
σ / kHz
N
2.4
23
F’ ← F’’=4 ←3
3←2
11256.0
11256.5
30,3←20,2
2←1
11257.0
IIb
IIa
IIIβb
IIIβc
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
A / MHz
4481
4479.03
3544
3557.20
3656
3638.05
4522
4517.47
3934
3931.75
3519
3510.40
B / MHz
1824
1830.16
2395
2380.37
2378
2387.89
1850
1846.99
2249
2242.76
2331
2321.90
C / MHz
1452
1443.79
1748
1740.92
1518
1519.18
1479
1463.79
1667
1664.53
1580
1584.38
χaa / MHz
- 4.66
- 4.302
- 3.67
- 3.461
- 3.89
- 3.652
χbb / MHz
2.92
2.823
2.21
2.079
2.13
2.062
χcc/ MHz
1.74
1.478
1.44
1.381
1.75
1.590
∆E / cm-1
0
22
Ia
11257.5
IIc
MP2
297
IIb
- 0.44
- 0.606
- 0.65
- 0.673
- 1.08
-1.048
2.05
2.072
- 0.53
- 0.456
- 0.75
-0.563
- 1.61
- 1.466
1.19
1.129
1.82
1.612
529
IIc
477
IIa
756
IIIβb
ν/ MHz
12
SERINE
Ia
assigned.
principal
A / MHz
B / MHz
C / MHz
30,3←20,2
3510.4015 (35)
2321.90829 (24)
1584.38608 (32)
∆J / kHz
∆JK / kHz
∆K / kHz
δJ / kHz
δK / kHz
0.504 (11)
[0.0]
[0.0]
[0.0]
[0.0]
χaa / MHz
χbb / MHz
χcc/ MHz
-1.0486 (55)
-0.5637 (53)
1.612 (21)
σ / kHz
N
F’ ← F’’=4 ←3
3←2
10858.5
IIc
IIa
IIIβb
IIIβc
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
MP2
Exp.
A / MHz
4481
4479.03
3544
3557.20
3656
3638.05
4522
4517.47
3934
3931.75
3519
3510.40
B / MHz
1824
1830.16
2395
2380.37
2378
2387.89
1850
1846.99
2249
2242.76
2331
2321.90
C / MHz
1452
1443.79
1748
1740.92
1518
1519.18
1479
1463.79
1667
1664.53
1580
1584.38
χaa / MHz
- 4.66
- 4.302
- 3.67
- 3.461
- 3.89
- 3.652
- 0.44
- 0.606
- 0.65
- 0.673
- 1.08
- 1.048
χbb / MHz
2.92
2.823
2.21
2.079
2.13
2.062
2.05
2.072
- 0.53
- 0.456
- 0.75
- 0.563
χcc/ MHz
1.74
1.478
1.44
1.381
1.75
1.590
- 1.61
- 1.466
1.19
1.129
1.82
1.612
∆E / cm-1
0
22
297
529
IIc
IIb
Ia
2←1
10859.0
IIb
MP2
477
IIa
756
IIIβb
IIIβc
10859.5
1.9
16
ν/ MHz
Supersonic jets:
jets: “Missing” conformers
SERINE : Observed Conformers
1.00
Type I
NH···O=C
Ia
0 cm-1
global
minimum
Ib
691 cm-1
High interconformer barriers
Ic
1002 cm-1
Preexpansion population
0.41
IIa
592 cm-1
0.12
Type II
OH···N
?
IIIαa
491cm-1
Type IIIα
NH···OH
0.27
IIb
22 cm-1
IIc
297 cm-1
IIIαb
1061 cm-1
IIIαc
1328 cm-1
PostPost-Expansion population
supersonic
expansion
Conformer 1
IIIβa
Type IIIβ
NH···OH
0.12
IIIβb
477cm-1
0.14
Population cooling
Conformer 1
Conformer 2
IIIβc
756cm-1
Conformer 2
Conformer 3
Conformer 3
MP4/6-311++G(d,p)
Supersonic jets:
jets: “Missing” conformers
Serine:
Serine: Interconversion barriers
Low interconformer barriers
Preexpansion population
High interconformer barriers
PostPost-Expansion population
Conformer 1
Conformer 2
Conformer 1
Conformer 2
2500
2000
IIc
1500
IIb
500
0
0
H
H
Conformer relaxation
IIa
1000
1
400
2000 cm-
1
∆E / cm-1
MP26-311++G(d,p)
3000
cm-
supersonic
expansion
COOH
OH
H
90
180
270
360
∠OCβCαC angle / degrees
NH2
13
Serine:
Serine: Interconversion barriers
Cysteine
Low interconformer barriers
1.2
missing
conformer
∆E / cm-1
MP2/6--311++G(d,p)
MP2/6
Observed Conformers
:
I
NH···O=C
0.3
IIIαa
II
200 cm-1
HOH2C
O
90
NH2
OH
180
IIa
1.0
527 cm-1
IIb
0 cm-1
IIc
1010 cm-1
IIIαa
848 cm-1
IIIαb
IIIαc
IIIα NH···OH
0
0
Ic
OH···N
Ia
Conformer relaxation
Ib
325 cm-1
global
minimum
1000
500
0.9
Ia
450 cm-1
270
360
IIIβa
∠NCαC=O angle / degrees
H
0.2
IIIβb 0.2
585 cm-1
IIIβ NH···OH
IIIβc
765 cm-1
MP4/6-311++G(d,p)
GABA (ácido γ-aminobutírico)
Low energy conformers
m.p. 195 C
0 cm-1
30 cm-1
216 cm-1
423 cm-1
129 cm-1
173 cm-1
One of the most important inhibitor neurotransmitters
High concentration in the Central Nervous System
365 cm-1
474 cm-1
GABA 324 conformers
506 cm-1
543 cm-1
677 cm-1
709 cm-1
MP2/6-311++G(d,p)
intramolecular interactions
F’ ← F’’=4 ←3
30,3←20,2
3←2
2←1
3←3
2←2
10238.0
MP2
A / MHz
B / MHz
C / MHz
σ / kHz
N
Experimental
4129
1835
4194.96418 (11)
1792.83867 (40)
1670
1630.69973 (35)
∆J / kHz
∆JK / kHz
∆K / kHz
δJ / kHz
δK / kHz
χaa / MHz
χbb / MHz
χcc/ MHz
10239.0
10240.0
ν/ MHz
1.3007 (84)
3.80 (16)
9.14 (30)
0.1020 (74)
[0.0]
-2.64
2.61
0.03
-2.2733 (20)
2.5532 (30)
-0.2799 (70)
2.8
54
n ··· π∗ remote delocalization
Burgi-Dunitz trajectory
NBO analysis
RHF/6-311++G(d,p)
MP2/6-311++G(d,p)
14
Glycine···H2O: Experimental setset-up
Glycine···H2O: Rotational spectrum
Once the transitions from Glycine I
and II were excluded
Parent
Rotational cons
A (MHz)
8437.979 (149)
B (MHz)
1613.41327 (71)
C (MHz)
1378.06131 (51)
F’-F’’=4-3
30,3-20,2
nuclear
quadrupole
hyperfine
components
Planar moment
Pc (u Å2)
F’-F’’=3-2
3.19871 (67)
Centrif. Distort.
DJ (kHz)
0.4296 (59)
DJK (kHz)
-1.359 (172)
DK (kHz)
[0.0]
dJ (kHz)
0.1019 (61)
dK (kHz)
[0.0]
14
χaa (MHz)
χbb (MHz)
χcc (MHz)
8950
N NQC tensor
-3.285 (27)
1.694 (67)
1.590 (67)
s (kHz)
3.1
N
30
H = HR(A) + HQ
Semirigid Rotor
Glycine···H2O: Experiment vs. theory
Experiment
Conformer
Ia
Parent
8437.979 (149)
B (MHz)
1613.41327 (71)
C (MHz)
1378.06131 (51)
Conformer
IIIa
Glycine···H2O: Isotopic species
15
Parent
Conformer Ia
7978
A (MHz)
8437.979 (149)
1614
1654
B (MHz)
1613.41327 (71)
1379
1404
C (MHz)
1378.06131 (51)
Planar moment
3.26
3.19871 (67)
N-glycine
···H2O
15
N-glycine
···H218O
8401.068 (109)
8374.89 (11)
1579.66148 (61)
1500.69207 (52)
1352.44092 (45)
1293.54511 (39)
4.47
Pc (u Å2)
3.19871 (67)
Centrif. Distort.
3.20301 (51)
N
3.20776 (51)
Centrifugal distortion constants
DJ (kHz)
0.4296 (59)
DJ (kHz)
0.4296 (59)
0.3834 (55)
-1.359 (172)
DJK (kHz)
-1.359 (172)
[0.0]
Conformer IIIa
0.3634 (47)
[0.0]
DK (kHz)
[0.0]
DK (kHz)
[0.0]
[0.0]
[0.0]
dJ (kHz)
0.1019 (61)
dJ (kHz)
0.1019 (61)
0.0777 (56)
0.0613 (18)
dK (kHz)
[0.0]
dK (kHz)
[0.0]
[0.0]
[0.0]
14
N NQC tensor
-3.285 (27)
1.694 (67)
1.590 (67)
s (kHz)
3.1
N
30
14
N quadrupole coupling tensor
-3.57
-3.95
1.69
2.14
1.88
1.80
Relative energy (kJ mol-1)
0.0
caa (MHz)
cbb (MHz)
ccc (MHz)
14
N nuclear quadrupole coupling tensor
-3.285 (27)
1.694 (67)
1.590 (67)
s (kHz)
3.1
1.8
1.6
Nc
30
11
11
4.7
Glycine···H2O: Structure
•Binding a single water molecule to Glycine proceeds through the carboxylic group
and gives rise to a closed ring structure with two simultaneous intermolecular
hydrogen bonds formed between the carbonyl group and one of the hydrogen
atoms of water (Ow-H···O=C) and between the hydroxyl group and the electron
lone pair at the oxygen atom of water (Ow···H-O-C).
Spectroscopy:
Historical Overview
LASER ABLATION COMBINED WITH
MICROWAVE SPECTROSCOPY IN A
SUPERSONIC JET MAY CONSTITUTES A
NEW TOOL WHICH CAN BE BROADLY
APPLIED TO ROTATIONAL SPECTRA OF
SOLIDS COMPOUNDS.
1.806(1) Å
Laser-ablation
MB-FTMW
MBFT-MW
Jets
161.8(1)º
Flygare
91.4(7)º
140º
O
Planar moment
DJK (kHz)
caa (MHz)
cbb (MHz)
ccc (MHz)
Conformer Ia
8440
Planar moment
Pc (u Å2)
Nuclear Quadrupole Term
MP2/6-311++G(d,p)
Rotational cons
A (MHz)
8951
ν / MHz
Solid
compounds
Flygare
FT-MW
Timedomain
126.4(5)º
112.4(1)º
2.073(2) Å
Stark modulation
Cleeton & Willians
•The structure of Glycine-Water retains the preferred conformation I of the
Glycine most stable form, with a cis-carboxylic group and a NH···O=C
bifurcated intramolecular hydrogen bond
Video mod.
MW &
MMW
Spectroscopy
NH3
15
GRUPO DE ESPECTROSCOPIA MOLECULAR
Funding:
Funding:
• Ministerio de Ciencia y Tecnología
• Junta de Castilla y León
16

Alonso_Pisa2005

Transcription

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