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

摘要

In order to further explore the inclusion complexation behavior with #beta#-cyclodextrin dimers, the binding constants (K_S) of three organoselenium bridged bis(#beta#-cyclodextrin)s (2-4) tethered with a short linker were determined with some representative dye molecules in aqueous phosphate buffer solution (pH 7.20) at 25 deg C by fluorescence and UV-vis spectrometry. As compared with the parent #beta#-cyclodextrin (1), the bridged bis(#beta#-cyclodextrin) (2-4) can not only significantly enhance the original binding affinity of the parent #beta#-cyclodextrin by the cooperative binding of one guest molecule in the closely located two #beta#-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(#beta#-cyclodextrin)s (2-4) are discussed from the viewpoint of the size/shape-fit concept and multiple recognition mechanism.