Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7595132 | Food Chemistry | 2015 | 6 Pages |
Abstract
The inclusion complex of 7-hydroxy-4-methylcoumarin (7H4MC) with sulfobutyl ether-β-cyclodextrin (SBE-β-CD) was investigated by means of UV-vis, circular dichroism and 1H NMR spectroscopy in phosphate buffer solutions at different temperatures and pH values. The stoichiometric ratio of the complexation was found to be 1:1 and the stability constants (KC) were estimated from phase solubility analysis. The thermodynamic parameters of standard Gibbs free energy change, ÎGo, enthalpy change, ÎHo, and entropy change, ÎSo, for the complexation process were obtained by using the van't Hoff equation and Gibbs-Helmholtz equation. The large negative ÎHo and the small negative or positive ÎSo (|ÎHo| > |TÎSo|) demonstrated that the inclusion interaction was an enthalpy-driven process. The positive signal of circular dichroism indicated that 7H4MC penetrated the cavity in such a way that the transition moment of the guest chromophore was parallel to the long axis of SBE-β-CD cavity. Moreover, the 1H NMR spectrum showed that the entire 7H4MC molecule, except the hydroxyl group, was included in the SBE-β-CD cavity.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Min Liu, Aiju Chen, Yong Wang, Chunmei Wang, Bingquan Wang, Dezhi Sun,