Physique des Lasers Atomes et Molcules UMR 8523

Physique des Lasers, Atomes et Molécules UMR 8523 CNRS – Université Lille 1, 59655 Villeneuve d’Ascq Cedex, France 60 th OSU International Symposium on Molecular Spectroscopy June 20 -24, 2005 AB INITIO CHARACTERIZATION OF THE STABLE CONFORMERS OF C 4 SUGARS: ERYTHROSE, ERYTHROSE ERYTHRULOSE AND THREOSE Juan Ramon AVILES MORENO, D. PETITPREZ and T. R. HUET

Content Ø Motivations Ø Short bibliography on Cn sugars: experimental and ab initio studies Ø This work: Erythrose Ø Ab initio calculations Ø Spectroscopy properties Ø Theoretical spectrum in the MW region Ø Conclusions and outlook

Motivations Why studying biomolecules ? Why in the gas phase ? Main role : - biological activity - charges tranfer - neurotransmission - molecular recognition : chirality, proteins Building blocks : - amino acids - neurotransmitors - nucleic basis - sugars

Carbohydrates: introduction SUGARS Cn. H 2 n. On Physico-chemical approach: studying isolated molecules in the gas phase. Goals: To perform ab initio calculations on Cn. H 2 n. On To evidence the spectra of Cn. H 2 n. On This work: n=4

Carbohydrates: introduction n=2 Glycolaldehyde C 2 H 4 O 2 2. 09 Å Experimental detection in the MW range in 1970: • K. M. Marstokk and H. Mollendal et al. J. Mol. Struct. 5(1970) 205 n=3 Glyceraldehyde • H. Mollendal et al. J. Mol. Struct. 16(1973) 259 C 3 H 6 O 3 • R. A. H. Butler et al. Astrophys. J. Supplement Series 7Å 134: 319 -321 (2001) 1 conformation found. initio calculations and microwave Some other studies on Ab bigger sugars: 2. 4 Detection in the interstellar cloud Sgr B 2(N) in 2000: Å spectroscopy in 2003: 2. 0 n=4 Erythose, erythrulose threose. J. Suppl. Ser. 554: L 81 -L 85 (2001) • J. M. Hollis et al. , Astrophys. 1 E=0. 0 k. J/mol • F. J. Lovas, R. D. Suenram, D. Plusquellic, an H. Mollendal, J. C H O 4 8 4 Ab initio calculations in 2004: α- and β-phenylxyloside and their Erythrose Mol. Spect. 222 mono-hydrated (2003), 263 -272. complexes: • T. Ratajczyk et al. J. Phys. Chem. A 108, 2758 (2004) • Susanna L. Widicus et al. J. Mol. (2005) Spect. 224 (2004), 101 -106. Isabel Hünig et al. Phys. Chem. 2474 • M. L. Senent. Chem. J. Phys. Chem. Phys. A 108, 7, 6286 (2004) 5 stable structures calculated Our at the work β-D-glucopyranoside: 4 stable structures Ab initio study of Fructose: MP 2/ 6 -311++G** level of theory n=5 Ribose , arabinose, xylose, lyxose Geometry optimized at the Chem. MP 2/cc-p. VQZ MP 4(SDTQ)/ F. O. Talbot and J. P. Simons Phys. Chem. Phys. and 4, 3562 (2002) cc-p. VQZ Chem. 3 conformations detected in the 10 -20 GHz range by C 5 H 10 Oet 5 al. Alice Chung-Philips J. Phys. A 103, 953 (1999) levels of theory. 1 E=0. 0 k. J/mol FTMWS Conformation of Furanose rings: n=6 Glucose, galactose, mannose, . . . Soc. 123, 8811 (2001) Justin B. Houseknecht et al. fructose J. Am. Chem. C 6 H 12 O 6

Ab initio calculations on C 4 sugars C 4 H 8 O 4 From ab initio calculations Aldehydes: • Erythrose Rotational constants • Threose A, B et C Erythrose Electric dipole moment Lines intensities Relative energies of different conformations Threose Ketone: • Erythrulose Theoretical spectrum Most stable structures

Ab initio calculations on C 4 sugars To the best of our knowledge, there is no experimental characterization of C 4 sugars in the gas phase Ab initio calculations on Erythrose: • Scan of the potential energy surface (HF/3 -21 G* et 6 -311++G**): 15 minima were found • Geometry optimization (B 3 LYP et MP 2/ 6 -311++G(2 df, p)): • Coupled-Cluster methods : no! (big computational cost) • Relative energy of different conformations (G 3 MP 2 B 3) Expected accuracy: 0. 5% for rotational constants 1 k. J/mol for relative energies of different conformations Finally we have found 14 stable structures Relation between H-bond and relative energy

The most stable conformers 2. 05 Å Å 5Å 2. 0 26 2. 2 2. 0 Å 4Å 3. 2 4 2 2. 2. 18 Å 3 E=2. 2 k. J/mol 2 E=1. 5 k. J/mol 1 E=0. 0 k. J/mol 2. 02 Å Å. 09 2 Å 2. 01 Å 2. 31 26 2. 29 Å Å Å 5 E=4. 2 k. J/mol H-bond lenght from B 3 LYP/6 -311++G(2 df, p) 2. 30 Å 2. 33 Å 4 E=3. 2 k. J/mol 6 E= 5. 3 k. J/mol Energies G 3 MP 2 B 3

Relative energy of the conformers Relative Energy G 3 MP 2 B 3 for Erythrose Conformation k. J/mol kcal/mol 1 b 0 0 4 a 1. 5 0. 4 3 a 2. 2 0. 5 2 c 3. 1 0. 7 2 b 4. 1 1. 0 1 a 5. 3 1. 3 2 a 7. 2 1. 7 3 c 7. 6 1. 8 1 c 8. 1 1. 9 10. 4 2. 5 • Many 3 bstructures under 5 k. J / mol 4 b 2. 5 • Theoretical spectrum from 10. 5 A, B, C and μ 5 a electric dipole moment: 11. 4 2. 7 • Strong 5 b spectrum can be detected 15. 0 3. 6 The in the MW region 5 c 18. 1 4. 3

Spectroscopic properties Å 2. 02 Å 20 2. 9 1. 9 Å 4 2. 2 Å 2. 14 Å 1 E=0. 0 k. J/mol 2 E=1. 5 k. J/mol Erythrose 1 b Erythrose 4 a A=2891. 5 MHz B=1695. 3 MHz C=1339. 3 MHz μa=1. 1 D μb=1. 2 D μc= 2. 0 D A=3743. 8 MHz B=1340. 8 MHz C=1106. 7 MHz μa= 3. 6 D μb= 0. 2 D μc= 0. 3 D MP 2/ 6 -311++G(2 df, p)

Simulation for the detection by molecular beam microwave Fourier transform spectroscopy MP 2/ 6 -311++G(2 df, p) a b 1 E=0. 0 k. J/mol Erythrose 1 b A=2891. 5 GHz B=1695. 3 GHz C=1339. 3 GHz μa=1. 1 D μb=1. 2 D μc= 2. 0 D Jmax = 20 Trot = 3 K Horizontal axis in MHz Vertical axis in arbitrary units in linear scale

Simulation for the detection by molecular beam microwave Fourier transform spectroscopy MP 2/ 6 -311++G(2 df, p) a b 2 E=1. 5 k. J/mol Erythrose 4 a A=3743. 8 GHz B=1340. 8 GHz C=1106. 7 GHz μa= 3. 6 D μb= 0. 2 D μc= 0. 3 D Jmax = 20 Trot = 3 K Horizontal axis in MHz Vertical axis in arbitrary units in linear scale

Possible detection by LA-MB-MWFTS MWFT spectrometer coupled to a molecular beam expansion • Heated nozzle : biomimetics-water complexes, small carbohydrates (Cn. H 2 n. On, n < 4) • Laser desorption technique : carbohydrates (n > 3) (in progress) Heated nozzle of the pulsed molecular beam Nd: YAG laser (532 nm, 25 m. J, 1 -15 Hz) fiber Mirror J. -R. Aviles Moreno (on the left, chemist), A. Cuisset (on the right, physicist) Neon …in the cavity Carbon /C 6 H 12 O 6 rod

Conclusions and outlook • Quantum chemistry is a main tool for studying the structure of biomolecules, for example sugars. • A conformational study of erythrose has been made, especially for the most stable conformations. • Rotational constants, electric dipole moments and relative energies of conformation have been obtained for the 14 stable structures of erythrose • To finish calculations for threose and erythrulose (in progress) • In the future, to use these calculations for the detection of Thanks: Jean DEMAISON for his precious help the spectra of the C 4 series with the LA-MB-MWFT IDRIS, Contract 51715 spectrometer…

1 E=0. 0 k. J/mol 2 E=5. 7 k. J/mol 3 E=8. 8 k. J/mol 5 E=11. 7 k. J/mol 4 E=9. 8 k. J/mol Energies MP 2/6 -311++G**

Experimental set-up: MB-MWFTS e n n 0 0 t Molecules polar gas t t source detection Source of microwave pulse (2 -20 GHz) Fourier transform of the transient signal Frequency analysis Physical parameters : m : permanent electric dipole moment e : amplitude of the microwave field t : length of the microwave pulse t n 0 n Matter-light interaction Inside a Pérot-Fabry resonator Þ Polarization of the polar molecules ; Rotational cooling Detection and recording of the signal Emitted by the molecules As a function of time Application rule : maximum polarization for a p/2 pulse, i. e.

Experimental set-up: MB-MWFTS Gas mixture Resonant cavity and pulsed supersonic beam Gaussian envelop (Ws= 42 mm at 12 GHz) R=800 mm Spectral range : 6 – 20 GHz MW pulse detection 600 mm<d< 650 mm Vacuum-tight rotation transition and step by step motor Carrier gaz 1. 5 bar Ar Resolution : 10 k. Hz Precision : 2. 4 k. Hz pump Heated nozzle 363 K Sensitivity : 10 -11 cm-1 Benzamide powder Cavity Rot. temp. : 4 K Pressures : Carrier gas: 1 -3 bars Molecules: 10 -2 bar Secondary pumping Labview interface Scan : 1 GHz/12 h

Synthétiseur 2 -20 GHz Cavité PF Interrupteur rapide Synthétiseur 2 -20 GHz ns+30 MHz ns Mélangeur t Amplificateur FI = 30 MHz Filtre passe-bande Impulsion microonde de 1 à 2 ms • Transition rotationnelle • Dédoublement Doppler Amplificateur RF A/D Convertisseur A/D