Excited states of six-membered aza-aromatic rings. Part VIII. Photochemical reactions, fluorescence, and protolytic equilibria in N-alkylated phenazinium ion–phenazyl free radical systems

Abstract

Electronic fluorescence spectra of the N-methylphenazyl free radical and its protonated form are reported. The protolytic pK values for the ground and first excited states of the species have been determined and compared with data on a series of related compounds. A hitherto obscure difference in the reduction mechanism of N-methyl and N-ethyl-phenazinium ions is explained by steric inhibition of the reaction path leading to dealkylation.