Inclusion Complexation of Benzyl Viologen by β-Cyclodextrin in DMF-H2O Mixed Solution

Complex formation between benzyl viologen and β-Cyclodextrin (βCD) in 9:1(v/v) DMF-H2O mixed solution was studied by cyclic voltammetry. In order to examine the probable mechanism of the reaction of benzyl viologen dication (BzV2+) and its reduced forms with βCD, cyclic voltammograms were digitally simulated. Detailed analysis of the mechanism by digital simulation revealed that in 9:1(v/v) DMF-H2O mixed solution, benzyl viologen mono-cation (BzV+∙) formed inclusion complex with βCD according to EC mechanism, while its fully reduced form (BzV°), could not form inclusion complex with βCD. Bonding equilibrium constant, Keq, pertaining to the bonding of BzV+∙ with βCD was estimated as 10.6 M-n. The second order rate constant for the reaction of BzV+∙ with βCD was determined as 4.93 M-nS-. By the use of this solvent system (9:1(v/v) DMF- H2O mixed solution) the comprehensive study of non-alkyl group substituted viologens and long alkyl chain viologens with βCD is possible