1. Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex Juan-Ramon Aviles-Moreno, Jean Demaison and Thérèse R. Huet Laboratoire de Physique des Lasers, Atomes et Molécules UMR 8523 CNRS – Université Lille 1, 59655 Villeneuve d’Ascq Cedex, France OSU International Symposium on Molecular Spectroscopy meeting, June 19-23, in Columbus, Ohio, USA CC-W-1 0+0+ 0-0- CC-W-2 CC-W-1 CC-W-2 CC-W-1

2. Glycolaldehyde: the simplest sugar structural formula : CH 2 OHCHO Marstokk, K.-M.; Møllendal, H. J. Mol. Struct. 1970, 5, 205-213. Butler, R. A. H.; De Lucia, F. C. ; Petkie, D. T.; Møllendal, H. ; Horn, A. ; Herbst, E. Ap. J. Supp. Ser. 2001, 134, 319-321. Weaver, S. L. W.; Butler, R. A. H.; Drouin, B. J.; Petkie, D. T.; Dyl, K. A.; De Lucia, F. C. ; Blake G. A. Ap. J. Supp. Ser. 2005, 158, 188-192. Ratajczyk, T.; Pecul, M.; Sadlej, J.; Helgaker, T. J. Phys. Chem. A 2004, 108, 2758-2769. Senent, M. L. J. Phys. Chem. A 2004, 108, 6286-6293. Experimental : micro-wave and millimeter-wave datas Ab initio calculations : structure + energy of 4 conformers (MP2/aug-cc-pVTZ and MP4/cc-pVQZ) A=18.474 GHz B=6.548 GHz C=4.984 GHz μ a =0.4D μ b =2.3D μ c =0.0D Glycolaldehyde 1 CC (C 2v ) (E = 0.0 kJ/mol) 2 TT E = 14.63 kJ/mol 3 TG E = 15.39 kJ/mol 4 CT E = 21.72 kJ/mol Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet

3. Hydrated glycolaldehyde (GA-W) Structures optimized at the B3LYP/6-311++G(2df,p) level of theory Energies: the Gaussian-3 (G3) compound method was used in its G3MP2B3 version as implemented in Gaussian 03 The two lowest experimentally accessible energy structures were also optimized using the B3LYP/aug-cc-pVTZ level of theory. CC-W-1 (0 kJ/mol) 197.5 186.4 CC-W-2 (2.12 kJ/mol) 186.0 197.4 CC-W-3 (4.03 kJ/mol) 194.4 209.6 CC-W-4 (5.83 kJ/mol) 200.0 214.2 Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet

4. Conformers CC-W-1 and CC-W-2 CC-W-1CC-W-2 GA skeleton: 4 O- 7 H/pm97.697.5 3 C- 4 O- 7 H/deg110.88111.49 1 O- 2 C- 3 C- 4 O/deg- 10.510.8 7 H- 4 O- 3 C- 2 C/deg46.944.1 Water skeleton: 9 H- 10 O/pm97.297.1 11 H- 10 O/pm96.296.1 9 H- 10 O- 11 H/deg106.42106.57 GA-W: 7 H- 10 O/pm186.5186.6 9 H- 1 O/pm195.4195.2 10 O- 9 H- 3 C- 2 C/deg161.1169.6 11 H- 10 O- 1 O- 2 C/deg135.5255.5 CC-W-1 (0 kJ/mol) 197.5 186.4 Principal Bond Lengths, Bond Angles, and Dihedral Angles (B3LYP/aug-cc-pVTZ ) CC-W-2 (2.12 kJ/mol) 186.0 197.4 Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet

5. The experimental setup Microwave Fourier transform spectrometer (6-20 GHz) coupled to a supersonic molecular jet * GA dimer: crystalline mixture of stereoisomers (Sigma Aldrich, purity 98%) Heated nozzle T= 363 K Mirror Inside the cavity… Glycolaldehyde * Carrier gas P= 3 bars (Ne) Carrier gas + H 2 O H2OH2O cavity Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet

6. GA-W: (J KaKc )’-(J KaKc )’’ The microwave spectrum of GA-W Signals: GA (red dots), water dimer (blue circles), GA-W (assigned lines)  Decomposition products: Acetic acid, formic acid and formaldehyde (high T). Methyl formate was not detected Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet

7. GA-W: the molecular parameters Constants 0+0+ 0-0- A/MHz 5616.5972(13)5616.6051(13) B/MHz 3483.4258(14)3483.4321(14) C/MHz 2285.7921(8)2285.7929(8)  J /kHz 6.45(4)6.47(4)  JK /kHz -14.24(14)-14.50(14)  K /kHz 21.94(11)21.31(11)  J /kHz 1.958(20)1.934(20)  K /kHz 5.16(25)6.00(25) Std/kHz 4.14.3  /amu.Å 2 -13.9648(2)-13.9645(2) The Doppler components are splitted (30 kHz): Semirigid rotor: I r representation, A reduction.  = -0.28. Large amplitude motion associated with two equivalent structures ? Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet

8. Conformational assignment Exp.CC-W-1CC-W-2CC-W-3CC-W-4 VTZ(2df,p)VTZ(2df,p) A/MHz5616.65551.85545.0.5577.85559.29883.417731.3 B/MHz3483.43595.63592.43553.63562.51887.41675.5 C/MHz2285.82309.42309.12277.12283.41877.91545.3  /amu.Å 2 -13.96-12.75-12.96-10.88-11.44-49.78-3.09  a /D strong-1.2-1.1-1.6-1.5-0.50.1  b /D medium0.60.71.21.31.50.6  c /D -0.2 2.42.51.40.0 The identity of the experimentally detected conformer is CC-W-1 CC-W-1 (0 kJ/mol) 197.5 186.4 Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet

9. Tunneling effect Structure of the transition state TS 1 (17.72 kJ/mol): Simple model: « Mirror » TS 1 CC-W-1 The conformational flexibility was investigated through a two dimensional potential energy surface calculated along the hydroxyl group (i. e. the 7 H- 4 O- 3 C- 2 C dihedral angle) and the free OH water group (i. e. the 11 H- 10 O- 1 O- 2 C dihedral angle) coordinates, and associated with the two most stable conformers (CC-W-1 and CC-W-2). Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet

10. Conformational flexibility The grid was built by steps of 5 degrees, as a function of the energy by optimizing the structure of the 1440 grid points at the B3LYP/6-31G* level of the theory. The structure of all the maxima and minima was also optimized at the B3LYP/6-311++G(2df,p) level. Finally the energy of the maxima and minima was calculated at the MP2/cc-pVQZ level of theory.  Results: TS1: 17.72 kJ/mol TS2: 4.36 kJ/mol TS3: 4.98 kJ/mol CC-W-1: 0 kJ/mol CC-W-2: 2.36 kJ/mol CC-W-1 CC-W-2 TS 1 TS 3 TS 2 Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet

11. Conformational flexibility The splitting of the lines is due to a tunneling effect between two equivalent structures of the CC-W-1 conformers. The energetically favourable path involves TS2, CC-W-2, and TS3. CC-W-1 CC-W-2 TS2 TS3 TS2 TS3 TS1 CC-W-1 CC-W-2 CC-W-1 TS1 CC-W-1 Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet

12. Acknowledgment The Institut du Développement des Ressources en Informatique Scientifique (contract IDRIS 51715, France) The Programme National de Physico-Chimie du Milieu Interstellaire (PCMI, France) CC-W-1 0+0+ 0-0- CC-W-2 CC-W-1 CC-W-2 CC-W-1 Manuscript submitted to the J. Am. Chem. Soc. Conformational Flexibility in Hydrated Sugars: The Glycolaldehyde-Water Complex J.-R. Aviles-Moreno, J Demaison and T. R. Huet