Spectroscopic and calorimetric studies of interactions between mitoxantrone and cucurbituril Q7 in aqueous solutions

Abstract

Fluorimetric, DOSY NMR and calorimetric studies indicate that the mitoxantrone (L) molecule is complexed by cucurbituril Q7 (Q) in diluted aqueous hydrochloric acid solutions (pH = 4–5). The process of creating a supramolecular complex with a 1: 2 stoichiometry (Q2L) is thermodynamically spontaneous (∆G < 0), strongly exothermic (∆H < 0) and is accompanied by an increasing order of reagents (T∆S < 0). The calculated equilibrium constant logK > 3 indicates that the resulting supramolecular complex is thermodynamically stable. The increase in electrolyte concentration (10 mM formate buffer with 140 mM NaCl) impedes the interaction of mitoxantrone with cucurbituril Q7 in an aqueous environment.