AB INITIO CHARACTERIZATION OF THE STABLE CONFORMERS OF C4 SUGARS: ERYTHROSEERYTHROSE,

ERYTHRULOSE AND THREOSEJuan 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, France60th OSU International Symposium on Molecular Spectroscopy

June 20-24, 2005

ContentContent MotivationsMotivations

Short bibliography on CShort bibliography on Cnn sugars: experimental sugars: experimental

and and ab initioab initio studies studies

This work: This work: ErythroseErythrose

Ab initio calculationsAb initio calculations

Spectroscopy propertiesSpectroscopy properties

Theoretical spectrum in the MW regionTheoretical spectrum in the MW region

Conclusions and outlookConclusions and outlook

Main role :- biological activity- charges tranfer- neurotransmission- molecular recognition : chirality, proteins

Building blocks :- amino acids- neurotransmitors- nucleic basis- sugars

Why studying biomolecules ? Why in the gas phase ?

Motivations

Physico-chemical approach: Physico-chemical approach: studying isolated molecules in the gas phase.studying isolated molecules in the gas phase.

Goals:Goals:To perform ab initio calculations on To perform ab initio calculations on CCnnHH2n2nOOnn To evidence the spectra of CTo evidence the spectra of CnnHH2n2nOOnn

This work: n=4 This work: n=4

Carbohydrates: introductionSUGARS CSUGARS CnnHH2n2nOOnn

n=2n=2 GlycolaldehydeGlycolaldehydeCC22HH44OO22

n=3n=3 GlyceraldehydeGlyceraldehyde CC33HH66OO33

n=4n=4 ErythoseErythose, erythrulose, threose, erythrulose, threose CC44HH88OO44

n=5n=5 RiboseRibose, arabinose, xylose, lyxose, arabinose, xylose, lyxose CC55HH1010OO55

n=6n=6 Glucose, galactose, mannose, Glucose, galactose, mannose, fructosefructose...... CC66HH1212OO66

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 Series134:319-321 (2001)1 conformation found. 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 structures4 stable structuresGeometry optimized at the Geometry optimized at the MP2/cc-pVQZ and MP4(SDTQ)/cc-pVQZ MP2/cc-pVQZ and MP4(SDTQ)/cc-pVQZ levels of theory.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 the5 stable structures calculated at theMP2/ 6-311++G** level of theoryMP2/ 6-311++G** level of theory 3 conformations detected in the 10-20 GHz range by 3 conformations detected in the 10-20 GHz range by FTMWSFTMWS1 E=0.0 kJ/mol

2.07

Å 2.4 Å

Our workErythrose

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)

Ab initio calculations on C4 sugars

CC44HH88OO44

Aldehydes:•ErythroseErythrose•ThreoseThreose

Ketone:•ErythruloseErythrulose

ErythroseErythrose ThreoseThreose

From From ab initio ab initio calculationscalculations

Rotational constantsRotational constantsA, B et CA, B et C

Electric dipole momentElectric dipole momentLines intensitiesLines intensities

Relative energies of differentRelative energies of differentconformationsconformations

Theoretical spectrumMost stableMost stablestructuresstructures

To the best of our knowledge, there is no experimental To the best of our knowledge, there is no experimental characterization of Ccharacterization of C44 sugars in the gas phase sugars in the gas phase

Ab initioAb initio calculations on calculations on ErythroseErythrose: :

•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 constants0.5% for rotational constants1kJ/mol for relative energies of different conformations1kJ/mol for relative energies of different conformations

Finally we have found Finally we have found 14 stable structures14 stable structures Relation between H-bond and relative energyRelation between H-bond and relative energy

Ab initio calculations on C4 sugars

The most stable conformers

Energies G3MP2B3Energies 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 Å3 E=2.2 kJ/mol

2.05 Å

2.24 Å

4 E=3.2 kJ/mol

2.02 Å

2.26 Å5 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)

Relative energy of the conformersRelative Energy G3MP2B3 for Erythrose

Conformation kJ/mol kcal/mol1b1b 00 004a4a 1.51.5 0.40.43a3a 2.22.2 0.50.52c2c 3.13.1 0.70.72b2b 4.14.1 1.01.01a1a 5.35.3 1.31.32a 7.2 1.7

3c 7.6 1.8

1c 8.1 1.9

3b 10.4 2.5

4b 10.5 2.5

5a 11.4 2.7

5b 15.0 3.6

5c 18.1 4.3

•Many structures under 5 kJ / mol•Theoretical spectrum from A, B, C and μ•Strong electric dipole moment:

The spectrum can be detectedThe spectrum can be detected in the MW regionin the MW region

Erythrose 1bErythrose 1b

A=2891.5 MHzB=1695.3 MHzC=1339.3 MHzμa=1.1D μb=1.2D μc= 2.0D

Erythrose 4aErythrose 4a

A=3743.8 MHzB=1340.8 MHzC=1106.7 MHzμa= 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

Simulation for the detection by molecular beam microwave Fourier transform spectroscopy

MP2/ 6-311++G(2df,p)

Jmax = 20Trot = 3K

Horizontal axis in MHzVertical axis in arbitrary units in linear scale

Erythrose 1bErythrose 1b

A=2891.5 GHzB=1695.3 GHzC=1339.3 GHzμa=1.1D μb=1.2D μc= 2.0D1 E=0.0 kJ/mol

a

b

MP2/ 6-311++G(2df,p)

Jmax = 20Trot = 3K

Horizontal axis in MHzVertical axis in arbitrary units in linear scale

Erythrose 4aErythrose 4a

A=3743.8 GHzB=1340.8 GHzC=1106.7 GHzμa= 3.6D μb= 0.2D μc= 0.3D2 E=1.5 kJ/mol

a

b

Simulation for the detection by molecular beam microwave Fourier transform spectroscopy

MWFT spectrometer coupled to a molecular beam expansion

• Heated nozzle : biomimetics-water complexes, small carbohydrates (CnH2nOn, 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 /C6H12O6

rod

…in the cavity

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 ofthe spectra of the C4 series with the LA-MB-MWFT spectrometer…Thanks: Jean DEMAISON for his precious help

IDRIS, Contract 51715

Energies MP2/6-311++G**Energies MP2/6-311++G**

1 E=0.0 kJ/mol 2 E=5.7 kJ/mol 3 E=8.8 kJ/mol

4 E=9.8 kJ/mol5 E=11.7 kJ/mol

t

detectionsource

polar gas

t0

Molecules

2

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 pulseSource of microwave pulse (2-20 GHz)(2-20 GHz)

Matter-light interactionMatter-light interactionInside a Pérot-Fabry resonatorInside a Pérot-Fabry resonator

Polarization of the polar molecules ;Polarization of the polar molecules ;Rotational coolingRotational cooling

Detection and recording of the signalDetection and recording of the signalEmitted by the molecules Emitted by the molecules

As a function of timeAs a function of timeFourier transform of the transient signal Fourier transform of the transient signal

Frequency analysis Frequency analysis

Experimental set-up: MB-MWFTS

Resonant cavity and pulsed supersonic

beam Spectral range :

6 – 20 GHzSensitivity :

10-11 cm-1

Resolution : 10 kHzPrecision : 2.4 kHzRot. temp. : 4 KPressures :Carrier gas: 1-3 barsMolecules: 10-2 bar

Secondary pumpingLabview interfaceScan : 1GHz/12h

Experimental set-up: MB-MWFTS

Heated nozzle 363 K

Benzamide powder

1.5 bar ArCarrier

gaz Cavity

Gas mixture

Vacuum-tightrotation transitionand step by step motor

Gaussian envelop(Ws= 42 mm at 12 GHz)

MW pulse

detection

pump

600 mm<d< 650 mm

R=800 mm

s

Interrupteurrapide

t

Impulsion microonde de 1 à 2 s

Synthétiseur2-20 GHz

Cavité PF

Amplificateur

A/D

FI = 30 MHz

Synthétiseur2-20 GHz

Mélangeur

Filtre passe-bande

Amplificateur RF

Convertisseur A/D

s+30 MHz

•Transition rotationnelle•Dédoublement Doppler