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The effects of perfluorination on carbohydrate-pi interactions: computational studies of the interaction of benzene and hexafluorobenzene with fucose and cyclodextrin

Authors
Journal
Physical Chemistry Chemical Physics
1463-9076
Publisher
The Royal Society of Chemistry
Publication Date
Keywords
  • Density-Functional Theory
  • Galactose-Specific Proteins
  • Der-Waals Interactions
  • Molecular Recognition
  • Aromatic Interactions
  • Noncovalent Interactions
  • Thermochemical Kinetics
  • Dispersion Corrections
  • Crystal-Structures
  • Analog Complexes
Disciplines
  • Chemistry
  • Computer Science

Abstract

The effect of benzene fluorination on C-H center dot center dot center dot pi p 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.

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