The effects of perfluorination on carbohydrate-pi interactions: computational studies of the interaction of benzene and hexafluorobenzene with fucose and cyclodextrin.
The effect of benzene fluorination on C-H...pi interactions is studied using a number of computational methods applied to a range of intermolecular complexes. High level wavefunction methods (CCSD(T)) predict a slightly greater interaction energy for complexes of benzene with methane or fucose, compared to corresponding complexes involving hexafluorobenzene. A number of more approximate treatments, DFT with the M06-2X functional, PM3-D* and MM methods, give interaction energies within 1 kcal mol(-1) of the high level values, and also correctly predict that the interaction energy is slightly greater for benzene compared to hexafluorobenzene. However, the DFT-D model used here predicts that the interaction energy is slightly greater for hexafluorobenzene. Molecular dynamics simulations, employing the GLYCAM-06 force field, validated here, are used to model the complexes of benzene and hexafluorobenzene with beta-cyclodextrin in aqueous solution. We predict the binding free energies of the complexes to be within 0.5 kcal mol(-1), and suggest that the different chemical shifts of the H5 protons observed in the two complexes arise from their slightly different structures, rather than from different binding energies.
School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Rajesh K
RK
Raju
Ian H
IH
Hillier
Neil A
NA
Burton
Mark A
MA
Vincent
Slimane
S
Doudou
Richard A
RA
Bryce
D001554:Benzene / Q000737:chemistry*; D005466:Fluorocarbons / Q000737:chemistry*; D005643:Fucose / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory; D013816:Thermodynamics; D047392:beta-Cyclodextrins / Q000737:chemistry*
D005466:Fluorocarbons; D047392:beta-Cyclodextrins; D005643:Fucose; C003005:hexafluorobenzene; D001554:Benzene; C031215:betadex