Fluorescence Studied of Dissociation Constant of Cyclodextrin With Phenol Derivatives

摘要

α-and β-cyclodextrins consisting of six and seven glucose residues respectively, have lipophilic cavities with different inner diameters. They form host-guest inclusion complexes with hydrophobic organic and organometallic guest molecules in aqueous solution. These host-guest complexes have proved to be excellent model systems for studying the nature of noncovalent bonding forces in aqueous media. They have provided valuable insights into the hydrophobic effect and London dispersion forces and are good model for understanding the specificity of enzyme substrate interactions [1] Evidence for the formation of inclusion complexes have been provided from calovimetric titration [2] NMR[33], circular dichroism[4], U V[1] and fluorescence spectra[5] and conductometric method[6] etc. H ere we report a new fluorimetric method for a study on the reaction of the host-guest inclusion complexes of cyclodextrin with phenols. Dissociation constants (Kd) of the inclusion complexes of some phenols with α-β-cyclodextrin are estimated based on the variation of the fluorescent intensity and modified Harad' equations.