The urea-water complex urea-water complex observed by jet cooled Fourier-transform microwave spectroscopy and studied by ab initio calculations. J.-R. AVILES-MORENO , A. CUISSET, T. DELEPORTE, T.R. HUET, D. PETITPREZ. Physique des Lasers, Atomes et Molécules UMR 8523 CNRS – Université Lille 1, 59655 Villeneuve d’Ascq Cedex, France 60th OSU International Symposium on Molecular Spectroscopy June 20-24, 2005
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Urea-water complex The urea-water complex observed by jet cooled Fourier-transform microwave spectroscopy and studied by ab initio calculations. J.-R.
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The urea-water complexurea-water complex observed by jet cooled Fourier-transform
microwave spectroscopy and studied by ab initio calculations.
J.-R. AVILES-MORENO, A. CUISSET, T. DELEPORTE, T.R. HUET, D. PETITPREZ.
Physique des Lasers, Atomes et Molécules
UMR 8523 CNRS – Université Lille 1, 59655 Villeneuve d’Ascq Cedex, France
60th OSU International Symposium on Molecular Spectroscopy
June 20-24, 2005
ContentContent Motivations:
Urea: history and structure
Urea-water complexUrea-water complex
Ab initio structure of the Urea-water complex
Experimental set-up: MB-MWFTS
Experimental spectrum:
Lines with H2O
Lines with D2O
Determination of a first experimental structure
Conclusions and outlook
•One of the Nature’s simplest biomolecule.
•A simplest diamide with 3 coordination sites.
•Important role in pharmaceutical chemistry
•Powerfull protein denaturing agent
•Anti-viral agent
Urea: history and structureUrea: history and structure (NH2)2C=O
b
a
• In the solid phase : planar a (C2v symmetry), intensive network of H-bonds
• In the gas phase : nonplanar and relatively floppy
microwave spectra b
ab initio calculations
MP2 / 6-311++G(d,p)
most stable conformer : anti form
a A S. Swaminathan et al, Acta Crystallogr., Sect B : struct. Sci. 40, 398, (1984)
b P. D. Godfrey, R. D. Brown and A. N. Hunter, J. Mol. Struct. 413-414, 405, (1997)
Urea: history and structureUrea: history and structure (NH2)2C=O
E/ kJ/mol
148 192180
5 kJ/mol
2
1
b
a
Conformer Plane C2v
1 Conformer Anti C2
2 Conformer Syn Cs
b
a
• To study the micro-solvation process of bio-molecules : possible bridge between the gas phase and the liquid phase
• To understand the hydrogen bond formation.
• Possible comparison between physico-chemical data
coming from experiment and ab initio calculations.
UREA - WATER COMPLEX : motivation of the workUREA - WATER COMPLEX : motivation of the work
1 Conformer H11 Anti Cs
ab
Ab initio calculations at the B3LYP / aug-cc-pVTZ level of theory
Similar to formamide-water: F.J. Lovas et al J. Chem. Phys. 88(2) 722-729(1988)
UREA - WATER COMPLEX : UREA - WATER COMPLEX : Ab initioAb initio structure structure
0
1
3
0.7
3.6
130 180 230
2
Dihedral angle H11-O10-O2-C1 / °
E/ kJ/mol
P.-O. Astrand, A. Wallqvist, G. Karlström, J. Chem. Phys. 100 (1994) 1262.
ab1.85 Å
2.09 Å
• Spectra recorded with a pulsed-nozzle MB-MWFTS in the 6-20 GHz frequency range.
• Optimization of the signal : T(K), carrier gas and pressure