Synthesis of bis dansyl-modified β-cyclodextrin liner trimer having multi-recognition sites and high hydrophobic environment

Fluorescent β-cyclodextrin (CyD) trimer linked with amine, which are (6A,6D-bis-deoxy-dansylamino-β-CyD)6-deoxy-bis-β-CyDs (β-1), has been synthesized in order to investigate their sensing ability for organic compounds such as bile acids. Host β-1 showed pure monomer fluorescence, exhibiting a decrement in fluorescence intensity on complexation of bile acid. The extent of fluorescence variation with a guest was employed to evaluate the sensing ability of β-1. The guest-induced variation in the fluorescence (ΔI) was used to describe the sensing ability of β-1. Host β-1 could detect ursodeoxycholic acid and chenodeoxycholic acid with remarkable sensitivities, although, could not detect deoxycholic acid and cholic acid. The behaviors of the appended moieties of β-1 during a host–guest complexation were studied by induced circular dichroism (ICD), fluorescence and absorption spectra and MM2-energy-minimized structure. The guest-induced variations in the absorption, fluorescence, and ICD intensity suggest that the appended moieties work as a hydrophobic cap to elevate binding ability, and this fact was supported by three-dimension MM2-minimized structure while a host–guest complexation occurred.