Structural investigations of pyridin-4-yl indolizine modified β-cyclodextrin derivatives as fluorescent chemosensors for organic guest molecules

In order to investigate the substituent effects on their conformations and spectroscopic properties, a series of pyridin-4-ylindolizine modified beta-cyclodextrin derivatives were studied by 2D NMR (ROESY spectra) in D2O, circular dichroism, and fluorescence spectroscopy. It was found that the linked indolizin-beta-cyclodextrin compounds exhibited two types of conformations, as a function of the substituent, in which fluorescent moieties formed either an intramolecular complex or were not included in the hydrophobic cavity of the macrocycle. Under addition of organic guest species in a phosphate buffer at neutral pH, the variation of emission fluorescence intensity showed that these compounds are of significance for detection of volatile organic molecules and adamantane derivatives and might be used as molecular chemosensor. (c) 2005 Elsevier Ltd. All rights reserved.