Study on the inclusion and solubilization processes of inclusion complex of carboxymethyl-β-cyclodextrin with CDOTP

The inclusion and solubilization processes of the inclusion complex between carboxymethyl-p-cyclodextrin and chloro1,4-dibenzyl-1, 4-dinitrogen diheterocycly [2,2,2] octane tungstic peroxide were investigated using ultraviolet spectrophotometry characterization. Association constant K-CD.Q = 1.07 x 10(6) L/mol and the inclusion ratio n = 3 were determined by means of competitive inclusion method with phenolphthalein. Moreover, based on solubilization experiment of inclusion complex, it can be found that the solubility is improved vastly compared with the guest without inclusion, especially in the condition of normal atmospheric temperature and weak alkaline solutions. Additionally, thermodynamic analysis of this inclusion process and relevant evaluation of thermodynamic parameters, such as Delta S, Delta K and Delta G have been investigated, which indicates that this process is unprompted, thermodynamically sustained and driven by both enthalpy and entropy, and especially depends on entropy. The possible prediction of inclusion structure has also been investigated. (C) 2013 Elsevier B.V. All rights reserved.