Guest-Induced Conformational Change of 6-Monosubstituted Cyclodextrin

Flexibly capped cyclodextrins 6-deoxy-6-(3-nitro-4-hydroxy-5-methylphenacylthio)-β-cyclo-dextrin, 6-deoxy-6-(4-pyridyldithio)-β-eyclodextrin, and 6-deoxy-6-(3-carboxy-4-nitrophenyl-dithio)-β-cyclodextrin were prepared in order to detect any conformational change of the host upon guest binding. The changes in the electronic, circular dichroism and/or NMR spectra of there modified cyclodextrins upon binding of several guests indicate conformational changes around the chromophoric moieties of the cyclodextrins. These conformational changes were shown to dependent on the size of the guest molecules. The present modification of β-cyclodextrin enhanced the binding ability of the cyclodextrin.