Abstract
Dibromomalonic acid (Br2MA) oxidizes the photoexcited state of the Ru(bpy)3 2+ complex, producing Br2. Br2MA also reduces Ru(bpy)3 3+, yielding Br-. The first of these reactions has a rate proportional to [H+] and plays an important part in the mechanism of photoinhibition of the Belousov−Zhabotinsky reaction. We propose a reaction mechanism that gives good agreement with the experimental data.