Theoretical studies on the binding affinities of β-cyclodextrin to small molecules and monosaccharides

Equilibrium geometries and electronic structures of complexes between beta-cyclodextrin (beta-CD) and some small molecules as well as monosaccharides were investigated by Austin Model 1 (AM1) to obtain binding energy of the complexes. It was indicated that beta-CD could bind the structurally similar solvent molecules and monosaccharides because of the negative binding energy of the complexes, and especially could show the chiral binding ability to monosaccharides with more hydroxyl groups, due to its chiral characteristics. The complexes were stabilized by the hydrogen bonding between beta-CD and guests. Based on the AM1 optimized geometries, the IR spectra were calculated by AM1 method. Vibration frequencies of O-H bonds in the guests were red-shifted owing to the weakening of the O-H bonds with the formation of the complexes. (C) Versita Warsaw and Springer-Verlag Berlin Heidelberg. All rights reserved.