Dimerization of cation radicals of N,N′-disubstituted 4,4′-dipyridylium derivatives in a polyvinyl alcohol matrix

1. It was established that the cation radicals of methyl- and heptylviologen dimerize in polyvinyl alcohol films. 2. The absorption bands were separated and the extinction coefficients were calculated for the dimeric and monomeric forms of the cation radicals in the range 30,000-9000 cm−1. 3. The dissociation constants of the dimers increase with decrease in the amount of water in the polyvinyl alcohol films. 4. The enthalpy and entropy of dimerization of the cation radicals of methyl- and heptylviologen were determined.