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.
Raju
Rajesh K
RK
School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Hillier
Ian H
IH
Burton
Neil A
NA
Vincent
Mark A
MA
Doudou
Slimane
S
Bryce
Richard A
RA
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