Molecular Recognition Studies on Supramolecular Systems. Part 38. Inclusion Complexation of Organic Dyes by Organoselenium Bridged Bis(β-cyclodextrin)s with a Short Linker

Abstract

In order to further explore the inclusion complexation behavior with β-cyclodextrin dimers, the binding constants (KS) of three organoselenium bridged bis(β-cyclodextrin)s (2ndash;4) tethered with a short linker were determined with some representative dye molecules in aqueous phosphate buffer solution (pH 7.20) at 25 °C by fluorescence and UV-vis spectrometry. As compared with the parent β-cyclodextrin (1), the bridged bis(β-cyclodextrin)s (2ndash;4) can not only significantly enhance the original binding affinity of the parent β-cyclodextrin by the cooperative binding of one guest molecule in the closely located two β-cyclodextrin cavities but also remarkably extend its molecular recognition abilities towards the different size/shape or substituent of model substrates. The higher binding ability and selectivity of dye molecules by bridged bis(β-cyclodextrin)s (2ndash;4) are discussed from the viewpointof the size/shape-fit concept and multiple recognition mechanism.