Stereoselective and driving-force-dependent photoinduced electron-transfer reactions of zinc myoglobin with optically active N,N'-dimethylcinchoninium and N,N'-dimethylcinchonidinium ions.

In order to understand the detailed mechanism of the stereoselective photoinduced electron-transfer (ET) reactions of zinc-substituted myoglobin (ZnMb) with optically active molecules by flash photolysis, we designed and prepared new optically active agents, such as N,N'-dimethylcinchoninium diiodide ([MCN]I2) and N,N'-dimethylcinchonidinium diiodide ([MCD]I2). The photoexcited triplet state of ZnMb, 3(ZnMb)*, was successfully quenched by [MCN]2+ and [MCD]2+ ions to form the radical pair of ZnMb cation (ZnMb.+) and reduced [MCN].