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Grupo de Espectroscopia Molecular, Unidad Asociada CSIC
Laboratorios de Espectroscopia y Bioespectroscopia
Edificio Quifima. Parque Científico
Universidad de Valladolid. SPAIN
EIGTH
SEVEN CONFORMERS OF PIPECOLIC
ACID IDENTIFIED IN THE GAS PHASE
CARLOS CABEZAS, ALCIDES SIMAO and JOSE L. ALONSO
International Symposium on Molecular Spectroscopy, June 20  24, 2016
Champaign-Urbana, Illinois, USA
Research in our group is devoted to :
*Rotational Spectra of Molecules of Astrophysical Interest
The combination of Lab. Data and Radioastronomy provides a power
capability for the detection and conclusive identification of molecular
species in the ISM
Frequency Domain
•
•
Stark Modulation MW: 8- 170 GHz
Millimeter and Submillimeterwave : 50- 1000 GHz
*Conformation and Structure of Biomolecules.
Rotational studies of solid biomolecules by FTMW spectroscopy in a
supersonic expansion combined with laser ablation techniques of
vaporization.
Time Domain
•
•
•
•
MB-FTMW: 5- 26 GHz
LA-MB-FTMW : 2- 10 GHz
LA-MB-FTMW : 4-26 GHz
CP-FTMW: 2- 40 GHz
Why Biomolecules in Gas Phase?
STRUCTURE
To understand the structure and
functionality of biological systems in
their native environments (in vivo
condensated phases) it is often
imperative to first understand these
properties for the isolated system in
the gas-phase.
FUNCTIONALITY
Why Amino Acids in Gas Phase?
Amino Acids in their natural condensed phases are stabilized
as by strong intermolecular interactions as zwitterions
which does not occur in the polypetide chain
The structural research of the neutral amino acids should
be conducted in gas phase where the they present an
unsolvated neutral form HN-CH(R)-COOH which represents
the best approximation of an amino acid residue in a
polipeptide chain.
Gas phase
Neutral
H2N−CH(R)−COOH
Condensed phase
Zwitterion
+ H N−CH(R)−COO3
bipolar ionized form
The 20 Natural Amino Acids
Ala
Gly
O
Val
H 2N
OH
Ser
Cys
O
O
HO
HS
OH
Thr
OH
Phe
Tyr
O
OH
Tryp
O
Asn
H 2N
OH
NH2
H 2N
O
OH
O
Arg
Gln
O
O
NH2
N
NH2
HN
Lys
OH
OH
NH2
HO
NH2
NH2
H
N
OH
NH2
OH
Hys
O
OH
S
NH2
NH2
O
O
O
HO
OH
O
Met
O
HO
NH2
NH
Glu
O
OH
NH2
NH2
Asp
O
OH
OH
NH2
NH2
NH2
NH2
O
OH
OH
OH
OH
Pro
O
O
O
O
Leu
Ile
O
H 2N
NH
OH
NH2
H 2N
O
N
H
OH
NH2
Pipecolic Acid
• Proline homologue (piperidine ring vs pyrrolidine ring)
• Can be produced from L-lysine (natural pathway envolves PIPO)
• It can be found in human physiological fluids, fungi and plants
• Constituent of various pharmaceutical compounds (ropivacaine, rapamycin...)
• Melting point : 280ºC
Pipecolic Acid
Proline
Pipecolic Acid
• Proline homologue (piperidine ring vs pyrrolidine ring)
• Can be produced from L-lysine (natural pathway envolves PIPO)
• It can be found in human physiological fluids, fungi and plants
• Constituent of various pharmaceutical compounds (ropivacaine, rapamycin...)
• Melting point : 280ºC
Pipecolic Acid
Proline
PCCP, 11,617 (2009)
Angew. Chem. 41, 4673 (2002)
Conformational Panorama of Pipecolic Acid: What Can We Expect?
L-Pipecolic Acid
H


N
H
COOH
H



C
ring configuration
H
N

COOH
H


C
N
H
COOH

Axial-equatorial
N
H
H
COOH
COOH
H
N



H


COOH
H
N

N
H
COOH



Ce
N
H
H
C
RH
H
O
C
O
I
(N-H···O=C)
and
cis-COOH
H

Ce
Ca
RH
Intramolecular
hydrogen
bonding
H
H

H
N
C
Ca
RH
O
C
O
N
H
H
C
O
C
O
H
II
(N···H-O)
H
III
(N-H···O-H)
and
cis-COOH
Conformational Panorama of Pipecolic Acid: What Can We Expect?
ΔE(cm-1)
ΔG
A
B
C
|µa|
|µb|
|µc|
Pc
138
20
3247
1094
942
1.1
1.8
0.0
40.55
-e-I
40
1
2562
1425
1166
0.3
1.1
0.3
59.24
-e-I
95
0
3264
1142
892
0.7
1.2
1.2
15.40
-a-II
0
49
2544
1447
1154
4.4
1.5
2.2
54.99
C
-e-II
181
182
3221
1123
959
5.1
1.2
0.6
39.97
C
-a-II
336
351
3199
1159
895
5.1
1.2
0.0
14.68
C
-e-III
210
102
3252
1144
897
0.8
1.4
1.2
16.88
C
-a-III
446
330
3248
1084
961
1.9
0.2
1.8
47.96
161
118
2536
1445
1177
0.3
1.1
0.3
59.82
Conformer
C
-a-I
C
C
C
C
C
-e-III
C
-e-I
C
-a-II
C
-e-I
C
-e-II
C
-a-I
C
-a-II
C
-e-III
C
-e-III
-a-III
Experimental Approach
Vaporization
Gas Phase Isolation
Supersonic Expansion
Laser Ablation
LA
Spectroscopic
Characterization
+
MB
FT-MW
+
FTMW
LA + MB-FTMW Spectroscopy
LA + CP-FTMW Spectroscopy
Experimental: CP-FTMW + Laser Ablation
Vaccum
Chamber
Picosecond
Laser
FT-MW
Spectrometer
Experimental: CP-FTMW + Laser Ablation
Jet
Diffusion
pump
Laser
Experimental: CP-FTMW + Laser Ablation
Jet
Diffusion
pump
Broadband Fourier Transform: Operation
Gas pulse
Ne
Laser pulse
Jet
Solid
sample
Diffusion
pump
Rotary
Nd:YAG laser
Laser
Broadband Fourier Transform: Operation
CP-FTMW
spectrometer
Gas pulse
Molecular emission
Ne
Laser pulse
Chirped MW
pulse
Detection
Diffusion
pump
Rotary
Broadband Fourier Transform: Operation
CP-FTMW
spectrometer
Gas pulse
Molecular emission
Ne
Laser pulse
Chirped MW
pulse
Detection
Diffusion
pump
Detection
Rotary
FT
Time-domain
Frequency-domain
Pipecolic Acid: Observed Conformers
C
C
C
-e-I
C
-a-II
C
-e-III
C
-e-I
C
-e-II
C
-a-III
-a-I
-a-II
Observation Type III
Pipecolic Acid
Alanine
Type III
Type I
< 275 cm-1
~ 450 cm-1
Grupo de Espectroscopia Molecular
Laboratorios de Espectroscopia
y Bioespectroscopia Edificio Quifima.
Universidad de Valladolid. Spain
Carlos Cabezas
Isabel Peña
Lucie Kolesnikova
Santiago Mata
Elena R. Alonso
Veronica Diez
Jose M. Rodriguez
Marta San Juan
Research Funded by: