PHOTOREDUCTION OF DOUBLE-BRIDGED VIOLOGEN POLYMER MATRIX FILM

Abstract

Photoreduction of double- bridged viologen 1b in polymermatrix film under UV-irradiation goes through two stages. In the first, 1b was reduced to its single cation radical 1b′ and its polymer films become green (λ_max=628nm) not blue the color for benzyl viologen (λ_max=600nm), because of the strong intramolecular interaction between the reduced bipyridinium cation radical unit and the unreduced bipyridinium cation unit in 1b′. Then, 1b′ is further reduced to the double cation radical 1b" and the polymerfilm turns to violet (λ_max=532nm) because of intramolecular pimerization of the two cation radical in 1b".