Further studies of one electron reduction of 1,10-phenanthroline-5,6-quinone in aqueous solutions

Abstract

One-electron reduction of 1,10-phenanthroline-5,6-quinone (PQ) in aqueous solutions was studied by pulse radiolysis. It was found that the initial transient species formed by the reaction of e aq − with PQ at neutral pH has an absorption spectrum with maxima at 365 nm and 480 nm. The decay of the species follows a first order kinetics to form a subsequent transient species with an absorption maximum at 490 nm. Similar changes were also observed at pH 4.1. The formation and decay kinetics of both initial and subsequent transients at various pHs were investigated. The ionic strength has no effect on the decay of the subsequent transient at 4.1. On the other hand, the decay at neutral pHs was accelerated dramatically with increasing ionic strength. The plot according to Bronsted Bjerrum equation gives a slope of ∼4.