Selective Fluorescent Molecular Sensing by Bis Dansyl-Modified [gamma]-Cyclodextrin Dimer

γ-Cyclodextrin dimer linked with ethylenediamine has been synthesized and then modified with dansyl moiety in the presence of N, N'-dicyclohexylcarbodiimide. The sensing ability and binding property of the titled compound are investigated for bile acids. The fluorescence intensity of the cyclodextrin dimer is decreased when a host-guest complex was formed. The value δΙ/Ι0 , where Ι and Ι0 are fluorescence intensities in the presence and absence of a guest and δΙ is Ι0-Ι, was used as a parameter of sensitivity. This host exhibits highly sensitive and selective molecular recognition ability for ursodeoxycholic acid, lithocholic acid and chenodeoxycholic acid. The behaviors of appended moieties of the host when a host-guest complexation is occurring were studied by induced circular dichroism (ICD) and fluorescence spectra. The ICD spectra patterns of the titled dimer were opposite to those of bis dansyl-modified γ-CyD reported previously. The guest-induced variations in the fluorescence and ICD intensity suggest that the appended moieties work as a hydrophobic cap.