CAGE ESCAPE YIELDS IN THE QUENCHING OF STAR-RU(BPY)3(2+) BY METHYLVIOLOGEN - PRESENCE OF TRIETHANOLAMINE AS A SACRIFICIAL ELECTRON-DONOR

Continuous and pulsed laser flash photolysis techniques have been used to determine the efficiency (eta-ce) with which the redox products are released into the bulk upon the oxidative quenching of *Ru(bpy)3(2+) by MV2+ in the absence and presence of TEOA as a sacrificial electron donor in aqueous solution. The value of eta-ce is diminished as the ionic strength (mu) of the solution increases, although the extent of the effect depends on whether or not TEOA is present: in the absence of TEOA, eta-ce = (3.8 + 4.8-mu-1/2)-1; in the presence of 0.1 M TEOA in alkaline solution, eta-ce = (3.8 + 9.0-mu-1/2)-1. TEOA is an effective scavenger of Ru(bpy)3(3+) at concentrations greater-than-or-equal-to 0.05 M and in the pH 8.5-11.5 range. In less alkaline solution, its protonation diminishes its reducing ability; in more alkaline solution, reactions between its degradation products and MV2+ yield additional equivalents of MV.+. The value of eta-ce is also a function of [Ru(bpy)3(2+)] with a transition at 20-50-mu-M between upper and lower plateau values.