Spectroscopic anatomy of molecular-imprinting of cyclodextrin. Evidence for preferential formation of ordered cyclodextrin assemblies.

The processes of molecular-imprinting of beta-cyclodextrin (beta-CyD) with cholesterol and stigmasterol (cross-linking agent = diisocyanate) have been analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy. These templates enormously promote the formation of dimers and trimers of beta-CyD, which are only inefficiently formed in their absence. These ordered assemblies are the guest-binding sites, in which two or three beta-CyD molecules cooperate to bind large steroids. Ordered assemblies are also formed when 2,6-di-O-methyl-beta-cyclodextrin is used in place of beta-CyD. Direct spectroscopic evidence for molecular-imprinting effect has been obtained. Molecular imprinting of CyDs is potent for tailor-made preparation of synthetic receptors for nanometer-scaled guests.