Role of dibromomalonic acid in the photosensitivity of the Ru(bpy)32+-catalyzed Belousov-Zhabotinsky reaction

Dibromomalonic acid (Br(2)MA) oxidizes the photoexcited state of the Ru(bpy)(3)(2+) complex, producing Br-2. Br(2)MA 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.