| Abstract;Flexible hosts, 6A,6B-; 6A,6C-; 6A,6D-; and 6A,6E-bis dansylglycine-modified .GAMMA.-Cyclodextrins (.GAMMA.-1, .GAMMA.-2, .GAMMA.-3, and .GAMMA.-4, respectively) have been synthesized as a sensing molecular for organic guests including terpenoids and bile acids. These host compounds show a pure monomer fluorescence whose intensity is decreased or enhanced upon addition of guest species. The value .DELTA.I/I0, where I and I0 are fluorescence intensities in the presence and absence of a guest and .DELTA.I is I0-I, was used as a parameter of sensitivity. These hosts exhibit highly sensitive and selective molecular recognition ability, particularly, for lithochoic acid, chenodeoxycholic acid, and ursodeoxycholic acid. The behaviors of the appended moieties of those hosts when a host-guest complexation occurs are studied by induced circular dichroism(ICD) spectra and fluorescence spectra change in accommodation of a guest. The ICD pattern of these hosts alone or in accommodation of a guest is very similar, which means that the behaviors of the appended moieties are going very similar way. The guest-induced variations in the fluorescence or ICD intensity suggest that the appended moieties act as a hydrophobic cap that enables the cyclodextrin to form 1:1 host-guest complexes. (author abst.) |
