Cyclodextrin Inclusion Complexes. Molecular Mechanics Calculations on the Modification of π-Face Selectivity†

Cyclodextrins (CDs) are cyclic oligosaccharides formed by R(1f4) linked D-glucose units.1,2 They are named R-, â-, and γ-CD depending on the number of glucose units in the macrocycle (six, seven, or eight, respectively). CDs are one of the most widely used systems in supramolecular chemistry,3 since they include a large variety of organic compounds inside their hydrophobic, torusshaped cavity. The structural study of CDs and of their complexes has been carried out by different techniques such as X-ray analysis,4 NMR spectroscopy,5 EPR,6 and electrochemical methods.7 Chemical shifts5-7 and kinetic and thermodynamic studies,8 as well as computational methods (CNDO,9,10 MD,11,12 and MM13-18 ), have been used to study the complexation process. CDs can be considered as models for enzyme-substrate interactions19 or as standards for molecular recognition.20