Geometry of α-cyclodextrin inclusion-complexes with some substituted benzenes deduced from C-13 NMR chemical shifts

The geometries of inclusion complexes of -cyclodextrin (-CD) with guests, benzoic acid, p-hydroxy benzoic acid, and p-nitrophenol in aqueous solution have been determined by comparing the complexation induced C-13 shifts of guest molecules with quantum chemical predictions. In the calculations, the non-polar environmental effect produced by the -CD cavity on the C-13 shifts of included guest molecule has been formulated by the so-called solvent effect theory. The geometries of the complexes predicted theoretically were consistent with those in aqueous solution determined by H-1 NMR and those in the solid by the X-ray method.Details containing a more complete methodology and complete data will be published elsewhere.