The Mechanism of Electron Transfer Reaction for Xanthene Dye-Sensitized Formation of Methy Viologen Radical

Article abstract of DOI:10.1246/bcsj.60.1573

Sensitized reduction of methyl viologen, MV²⁺, occurs efficiently through electron transfer from triplet xanthene dyes to MV²⁺ followed by electron transfer to the resulting semioxidized dyes from a reductant like triethanolamine.Unreactive ion pair complexes between these dyes and MV²⁺ are formed (formation constant: 1.2E3 M^-1 for Eosine Y and MV²⁺ in 50 percent aqueous ethanol solution).The quantum yield for the reduced methyl viologen radical depends on the concentrations of MV²⁺ and the amine and on the ionic strength of solution.The efficiency of electron transfer from triplet dyes to MV²⁺ is increased by addition of alcohol, and solvent effects on the reaction mechanism are discussed.