Spectral properties and supramolecular inclusion complexes of beta-cyclodextrin with flexible amphiphilic and rigid compounds

摘要

Spectral properties and inclusion complexes of beta-cyclodextrin (beta-CD) with nonionic amphiphiles and rigid 1-bronionaphthalene (BrN) was investigated in detail. Fluorescence and H-1 NMR measurements give new insights into inclusion of the hydrophobic moiety of amphiphiles into the cavity of beta-CD. Their apparent stability constants were well con-elated with the structure of the hydrophobic moiety of amphiphiles. The long and flexible hydrophobic moiety may occupy the cavity in the compressed manner. The phosphorescence quenching and the binding strength of BrN in ternary complexes indicate that the inclusion depth and the rigidity of BrN in the cavity of beta-CD are predominant factors in determining its phosphorescence. Further inclusion of rigid BrN into the cavity drives the built-in phenyl group of amphiphiles to expose to bulk water phase to a greater extent. Comparative analyses of molecular sizes and models reveal that the flexible hydrocarbon chain of an amphiphile in supramolecular inclusion complexes was located inside the crowded cavity of beta-CD due to the filling of rigid BrN into the cavity. (c) 2005 Elsevier B.V. All rights reserved.