1. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
PABLO PINACHO
SUSANA BLANCO
JUAN CARLOS LÓPEZ
Departamento de Química Física y Química Inorgánica
Universidad de Valladolid, Valladolid
SPAIN

2. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Interactions between peptide groups and water may be modelled from the study of gas phase microsolvated clusters of simple molecules such as formamide.

3. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Interactions between peptide groups and water may be modelled from the study of gas phase microsolvated clusters of simple molecules such as formamide.
cis-peptide ~1%
trans-peptide ~99%
Ca-R
R-Ca
Ca-R
FW-1:1c
FW-1:1a
14% In proteins
R-Ca
Ca-R
R-Ca
FW-1:1b
42% in proteins

4. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Interactions between peptide groups and water may be modelled from the study of gas phase microsolvated clusters of simple molecules such as formamide.
cis-peptide ~1%
trans-peptide ~99%
Ca-R
R-Ca
Ca-R
FW-1:1c
FW-1:1a
14% In proteins
R-Ca
Ca-R
R-Ca
FW-1:1b
42% in proteins

5. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
We have analyzed the rotational spectra of formamidem-(H2O)n (m,n=1,2) clusters:
1) To characterize the different 1:1, 1:2, 2:1 conformers.
FW-1:1a
FW-1:1c
FW-2:1
FW-1:2a
FW-1:1b
S. Blanco et al., JACS 128(37) (2006)
S. Blanco et al., Ang. Chem. Int. Ed. (2016)

6. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
We have analyzed the rotational spectra of formamidem-(H2O)n (m,n=1,2) clusters:
1) To characterize the different 1:1, 1:2, 2:1 conformers.
2) To search for evidences of cooperative effects such as polarization enhanced or
resonance assisted hydrogen bonding.
1.343 Å
1.350 Å
rC-N = Å
shortening of HB lengths
r(C-N) decrease
S. Blanco et al., JACS 128(37) (2006)
S. Blanco et al., Ang. Chem. Int. Ed. (2016)

7. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
In these contest we have analyzed the rotational spectra of formamide-(H2O)3 cluster
1) To characterize the different 1:1, 1:2, 2:1 conformers.
2) To search for evidences of cooperative effects such as polarization enhanced or
resonance assisted hydrogen bonding.
1.341 Å
1.342 Å
1.343 Å
1.350 Å +
rC-N = Å
shortening of HB lengths ?
r(C-N) decrease ?
S. Blanco et al., JACS 128(37) (2006)
S. Blanco et al., Ang. Chem. Int. Ed. (2016)

8. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Formamide-(H2O)3 conformers
FW1+FW2
Parameter(a)
FW1-b ’b c
FW2a-FW1b
FW2a-FW1c
FW2b-FW1a
E/ cm-1
E/ kJmol-1
A/MHz
B/MHz
C/MHz

9. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Formamide-(H2O)3 conformers
Cloud
Parameter(a)
C-top-u
C-top-d
C-back
C-front
E/ cm-1
E/ kJmol-1
A/MHz
B/MHz
C/MHz

10. supersonic jet - sample
A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Spectrum
A/D
D/A
I/O
GP-IB
Control
pulso
molecular
generador
pulsos
10 MHz
ordenador PC n
- 160
MHz
160 MHz
FTMW spectrometer
Fabry-Pérot cavity
supersonic jet - sample
MB-FTMW (4-16 GHz)
Chem. Phys (1997);
Chem. Phys (2003)

11. Liquid sample of formamide
A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Spectrum
Heated Nozzle
Heater
50ºC
(F)m ··· (H2O)n
Carrier gas Ne
12 bar
Ne + H2O
H2O
Liquid sample of formamide
b.p. 210ºC

12. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Spectrum
Gas pulse
Diff.
pump
Rotatory
Fabry-Pérot
resonator
Molecular beam
MW pulse
Polarization
Detection
MW field FT
Time-domain
Frequency domain

13. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Spectrum
6500 MHz
11500 MHz
9000 MHz
FW-1:1c
FW-1:2a
FW-2:1 F
FW-1:1a
FW-1:1b

14. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Spectrum
6000 MHz
12000 MHz
9000 MHz

15. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Spectrum: inversion large amplitude motion or
11 kJ mol-1
16 kJ mol-1

16. rHf···Ow = 1.886 Å / rHw···Of = 1.810 Å
A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Evidences of cooperative effects such as polarization enhanced or
resonance assisted hydrogen bonding. -
rHf···Ow = Å
rHw···Of = Å
rHw···Ow = Å
rHf···Ow = Å / rHw···Of = Å -
rOw···Of = Å
rOw···Ow = Å
rOw···Of = Å
shortening of HB lengths
S. Blanco et al., JACS 128(37) (2006)
S. Blanco et al., Ang. Chem. Int. Ed. (2016)

17. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
Evidences of cooperative effects such as polarization enhanced or
resonance assisted hydrogen bonding.
rC-N = Å
1.350 Å
1.343 Å
r(C-N) decrease
S. Blanco et al., JACS 128(37) (2006)
S. Blanco et al., Ang. Chem. Int. Ed. (2016)

18. A STUDY OF THE FORMAMIDE-(H2O)3 COMPLEX BY MICROWAVE SPECTROSCOPY
PABLO PINACHO
SUSANA BLANCO
JUAN CARLOS LÓPEZ
Departamento de Química Física y Química Inorgánica
Universidad de Valladolid, Valladolid
SPAIN