Selective fluorescent molecular sensing by bis dansyl-modified gamma-cyclodextrin dimer

gamma-Cyclodextrin dimer linked with ethylenediamine has been synthesized a nd then modified with dansyl moiety in the presence of N,N'-dicyclohexylcar bodiimide. The sensing ability and binding property of the titled compound are investigated for bile acids. The fluorescence intensity of the cyclodex trin dimer is decreased when a host-guest complex was formed. The value Del ta I/I-0, where I and I-0 are fluorescence intensities in the presence and absence of a guest and Delta I is I-0-I, was used as a parameter of sensiti vity. This host exhibits highly sensitive and selective molecular recogniti on ability for ursodeoxycholic acid, lithocholic acid and chenodeoxycholic acid. The behaviors of appended moieties of the host when a host-guest comp lexation is occurring were studied by induced circular dichroism (ICD) and fluorescence spectra. The ICD spectra patterns of the titled dimer were opp osite to those of bis dansyl-modified gamma-CyD reported previously. The gu est-induced variations in the fluorescence and ICD intensity suggest that t he appended moieties work as a hydrophobic cap.