Study of Electron Transfer Reactions Associated with Benzyl Viologen-β-Cyclodextrin Complexation in Buffer Solution of pH 7: Equilibrium and Kinetic Aspects

Abstract

In this study, complex formation of benzyl viologen dication (BzV2+) with β-cyclodextrin (β-CD), in its different oxidation states, had been studied in buffer solution of pH 7, through cyclic voltammetry. In buffer solution of pH 7, extensive deposition of benzyl viologen neutral (BzVº) has been found. Further to that first redox process of BzV2+ was found reversible in buffer solution of pH 7. Benzyl viologen mono-cation (BzV+•) was found to interact with β-CD reversibly according to EC mechanism. Equilibrium constant of BzV+•-nβ-CD complex in buffer solution of pH 7, has been calculated as 5.49 M-n. The value of n was found to be 0.2. The bimolecular rate constant for the complex formation of BzV+• with β-CD was found to be 6.44 M-ns− in buffer solution of pH 7. This study is based upon an electrochemical approach to obtain the bonding equilibrium constant, the rate constants of formation and the association numbers of the complex formed between reduced forms of viologen and β-CD. This study explore the electron transfer reaction mechanism of benzyl viologen with β-CD to extend their applications at neutral pH.