Analysis of the conformational behaviour of perfunctionalized β-cyclodextrins. Part 1. Evidence for insertion of one of the rim substituents into the cyclodextrin cavity in organic solvents

Several functionalized β-cyclodextrins have been shown to exhibit conformational isomerism. The analysis of the conformational behaviour of several derivatives strongly suggests that a slow exchange occurs between C7 and C1 conformers, the C1 probably involving insertion of one of the primary rim substituents in the cyclodextrin cavity. The significance of the structural features of cyclodextrin substituents for the occurrence of conformational isomerism is examined. The relevance of the use of cyclodextrins for the design of molecular devices is discussed.