Fluorescent Chemo-Sensor for Organic Guests Based on Regioselectively Modified 6^A,6^B-, 6^A,6^C-, and 6^A,6^D-Bisdansylglycine-Modified β-Cyclodextrins

Abstract

Flexible hosts, 6^A,6^B-, 6^A,6^C-, and 6^A,6^D-bis-dansylglycine-modified β-cyclodextrins (β-1, β-2, and β-3, respectively) have been synthesized as a fluorescent chemo-sensor for organic guests including terpenoids and bile acids. Molecular sensing abilities obtained as fluorescence spectral changes of these hosts on accommodation of guests were almost twice those of γ-analogues. The sequence of binding ability of β-analogues is β-2> β-1> β-3. The molecular recognition behaviors of dansyl moieties of the title compounds are studied by induced circular dichroism (ICD), fluorescence, and absorption spectra without and with the guest. These spectral variations suggest that the appended moieties move out far from the cavity of β-cyclodextrin when host-guest complexation occurs.