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

Complex formation between benzyl viologen and beta-Cyclodextrin (beta CD) 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 (BzV(2+)) and its reduced forms with beta CD, 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(+center dot)) formed inclusion complex with beta CD according to EC mechanism, while its fully reduced form (BzV degrees), could not form inclusion complex with beta CD. Bonding equilibrium constant, K-eq, pertaining to the bonding of BzV(+center dot) with beta CD was estimated as 10.6 M-n. The second order rate constant for the reaction of BzV(+center dot) with beta CD 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 beta CD is possible.