The photochemistry of Ru(bpy)₃²⁺ in basic medium

Abstract

Ru(bpy)32+ is photodecomposed in 0.3 M NaOH with [Formula: see text]. With methyl viologen also present, electron transfer quenching of the luminescence is accompanied by formation of the one electron reduction product of methyl viologen, MV+. The Ru(bpy)33+ formed in the corresponding oxidation is rapidly reduced by either OH− or MV+ to Ru(II).

Quantum yield of formation of methylviologen radical cation in the photolysis of the Ru(bpy)32+/methylviologen/EDTA system

“…In this study, no MV"1"• was formed at any pH in the absence of EDTA; it should be noted that the photosensitized formation of MV"1"• in highly alkaline solution in the absence of EDTA has been reported. 19,33 The competition between reactions 3 and 4 for the removal of Ru(bpy)33+ lies at the core of the generation of MV"1"•, There appears to be no controversy over the nature of reaction 3; the value of k¡ has been well established3,34 to be (2.6 ± 0.2) X 109 M'1 s'1, independent of pH. However, published values of fc4, and reports of the behavior of the system relative to the competition between reactions 3 and 4, show very large variations even for experiments performed under very similar conditions at the same pH.…”