Search for a One-Electron Reduction of the Cation Radical of an 'Extended Viologen',p-Phenylene-bis-4,4'-(1-Aryl-2,6-Diphenylpyridinium)

摘要

Electrochemical one-electron reduction of the "extended viologen" dication 1{sup}(2+) proceeds reversibly at -0.64V (vs. Ag|AgCl electrode) to yield the red cation radical 1{sup}(+·), which readily produces a dark blue dimer hindering the observation of a second one-electron reduction of 1{sup}(+·). Conventional electrochemical methods suggest that the only second reduction step occurs at -1.4V. Fast cyclic voltammetry at scan rates up to kV/s and voltammetry at micromolar concentrations eliminate the coupled bimolecular chemical reactions and permit the determination of the reduction potential of the cation radical 1{sup}(+·).