Strong Guest Binding by Cyclodextrin Hosts in Competing Nonpolar Solvents and the Unique Crystalline Structure

6-O-Modified beta-cyclodextrins, such as heptakis(6-O-triisopropylsilyl)-beta-cyclodextrin (TIPS-beta-CD) and heptakis(6-O-tert-butyldimethylsilyl)-beta-cyclodextrin (TBDMS-beta-CD), formed 2:1 Inclusion complexes with pyrene in benzene and cyclohexane with high association constants. The X-ray crystalline structure of the TIPS-beta-CD-pyrene complex obtained from the benzene solution showed that one pyrene molecule was incorporated in the form of a sandwich-type complex with two benzene molecules within the cavity of the dimer formed by two TIPS-beta-CD molecules.