1. ERYTHROSE AB INITIO CHARACTERIZATION OF THE STABLE CONFORMERS OF C 4 SUGARS: ERYTHROSE, ERYTHRULOSE AND THREOSE Juan Ramon AVILES MORENO, D. PETITPREZ and T.R. HUET 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

2. Content  Motivations  Short bibliography on C n sugars: experimental and ab initio studies  This work: Erythrose  Ab initio calculations  Spectroscopy properties  Theoretical spectrum in the MW region  Conclusions and outlook

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

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

5. n=2 Glycolaldehyde C 2 H 4 O 2 n=3 Glyceraldehyde C 3 H 6 O 3 C 3 H 6 O 3 n=4 Erythose, erythrulose, threose C 4 H 8 O 4 C 4 H 8 O 4 n=5 Ribose, arabinose, xylose, lyxose C 5 H 10 O 5 C 5 H 10 O 5 n=6 Glucose, galactose, mannose, fructose... C 6 H 12 O 6 C 6 H 12 O 6 Carbohydrates: introduction Experimental detection in the MW range in 1970: K.M. Marstokk and H. Mollendal et al. J. Mol. Struct. 5(1970) 205 H. Mollendal et al. J. Mol. Struct. 16(1973) 259 R.A.H. Butler et al. Astrophys. J. Supplement Series 134:319-321 (2001)  1 conformation found. Detection in the interstellar cloud Sgr B2(N) in 2000: J.M. Hollis et al. Astrophys. J. Suppl. Ser. 554:L81-L85 (2001) Ab initio calculations in 2004: T. Ratajczyk et al. J. Phys. Chem.A 108, 2758 (2004) M.L. Senent J. Phys. Chem. A 108, 6286 (2004)  4 stable structures Geometry optimized at the MP2/cc-pVQZ and MP4(SDTQ)/cc-pVQZ levels of theory. 1 E=0.0 kJ/mol 2.09 Å Ab initio calculations and microwave spectroscopy in 2003: F.J. Lovas, R.D. Suenram, D. Plusquellic, an H. Mollendal, J. Mol. Spect. 222 (2003), 263-272. Susanna L. Widicus et al. J. Mol. Spect. 224 (2004), 101-106.  5 stable structures calculated at the MP2/ 6-311++G** level of theory  3 conformations detected in the 10-20 GHz range by FTMWS 1 E=0.0 kJ/mol 2.07 Å 2.4 Å Our work Erythrose Conformation of Furanose rings: Justin B. Houseknecht et al. J. Am. Chem. Soc. 123, 8811 (2001) Ab initio study of Fructose: Alice Chung-Philips et al. J. Phys. Chem. A 103, 953 (1999) Some other studies on bigger sugars: α- and β-phenylxyloside and their mono-hydrated complexes: Isabel Hünig et al. Phys. Chem. Chem. Phys. 7, 2474 (2005) β-D-glucopyranoside: F.O. Talbot and J.P. Simons Phys. Chem. Chem. Phys. 4, 3562 (2002)

6. Ab initio calculations on C 4 sugars C4H8O4C4H8O4C4H8O4C4H8O4 Aldehydes: ErythroseErythrose ThreoseThreose Ketone: ErythruloseErythrulose Erythrose Threose From ab initio calculations Rotational constants A, B et C Electric dipole moment Lines intensities Relative energies of different conformations Theoretical spectrum Most stable structures

7. 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/3-21G* et 6-311++G**):  15 minima were found Geometry optimization (B3LYP et MP2/ 6-311++G(2df,p)): Coupled-Cluster methods : no! ( big computational cost) Relative energy of different conformations (G3MP2B3)  Expected accuracy: 0.5% for rotational constants 1kJ/mol for relative energies of different conformations Finally we have found 14 stable structures  Relation between H-bond and relative energy Ab initio calculations on C 4 sugars

8. The most stable conformers Energies G3MP2B3 1 E=0.0 kJ/mol 2.02 Å 2.26 Å 2.34 Å 2 E=1.5 kJ/mol 2.05 Å 2.18 Å 3 E=2.2 kJ/mol 2.05 Å 2.24 Å 4 E=3.2 kJ/mol 2.02 Å 2.26 Å 5 E=4.2 kJ/mol 2.09 Å 2.29 Å 2.33 Å 6 E= 5.3 kJ/mol 2.01 Å 2.31 Å 2.30 Å H-bond lenght from B3LYP/6-311++G(2df,p)

9. Relative energy of the conformers Relative Energy G3MP2B3 for Erythrose ConformationkJ/molkcal/mol 1b00 4a1.50.4 3a2.20.5 2c3.10.7 2b4.11.0 1a5.31.3 2a7.21.7 3c7.61.8 1c8.11.9 3b10.42.5 4b10.52.5 5a11.42.7 5b15.03.6 5c18.14.3 Many structures under 5 kJ / mol Theoretical spectrum from A, B, C and μ Strong electric dipole moment: The spectrum can be detected in the MW region

10. Erythrose 1b A=2891.5 MHz B=1695.3 MHz C=1339.3 MHz μa=1.1D μb=1.2D μc= 2.0D Erythrose 4a A=3743.8 MHz B=1340.8 MHz C=1106.7 MHz μa= 3.6D μb= 0.2D μc= 0.3D 1 E=0.0 kJ/mol 2 E=1.5 kJ/mol MP2/ 6-311++G(2df,p) 1.99 Å 2.20 Å 2.24 Å 2.02 Å 2.14 Å Spectroscopic properties

11. Simulation for the detection by molecular beam microwave Fourier transform spectroscopy MP2/ 6-311++G(2df,p) J max = 20 T rot = 3K Horizontal axis in MHz Vertical axis in arbitrary units in linear scale Erythrose 1b A=2891.5 GHz B=1695.3 GHz C=1339.3 GHz μ a =1.1D μ b =1.2D μ c = 2.0D 1 E=0.0 kJ/mol a b

12. MP2/ 6-311++G(2df,p) J max = 20 T rot = 3K Horizontal axis in MHz Vertical axis in arbitrary units in linear scale Erythrose 4a A=3743.8 GHz B=1340.8 GHz C=1106.7 GHz μa= 3.6D μb= 0.2D μc= 0.3D 2 E=1.5 kJ/mol a b Simulation for the detection by molecular beam microwave Fourier transform spectroscopy

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

14. 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 the spectra of the C 4 series with the LA-MB-MWFT spectrometer… Thanks: Jean DEMAISON for his precious help IDRIS, Contract 51715

15. Energies MP2/6-311++G** 1 E=0.0 kJ/mol2 E=5.7 kJ/mol 3 E=8.8 kJ/mol 4 E=9.8 kJ/mol 5 E=11.7 kJ/mol

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

17. Resonant cavity and pulsed supersonic beam Spectral range : 6 – 20 GHz Sensitivity : 10 -11 cm -1 Resolution : 10 kHz Precision : 2.4 kHz Rot. temp. :  4 K Pressures : Carrier gas: 1-3 bars Molecules: 10 -2 bar Secondary pumping Labview interface Scan : 1GHz/12h Experimental set-up: MB-MWFTS Heated nozzle 363 K Benzamide powder 1.5 bar Ar Carrier gaz Cavity Gas mixture Vacuum-tight rotation transition and step by step motor Gaussian envelop (W s = 42 mm at 12 GHz) MW pulse detection pump 600 mm<d< 650 mm R=800 mm

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