Proton Pump for O₂ Reduction Catalyzed by 5,10,15,20‐Tetraphenylporphyrinatocobalt(II)

Abstract

The role of 5,10,15,20-tetraphenylporphyrinatocobalt(II) ([Co(tpp)]) as a catalyst on molecular oxygen (O(2)) reduction by ferrocene (Fc) and its two derivatives, 1,1'-dimethylferrocene (DFc) and decamethylferrocene (DMFc) at a polarized water|1,2-dichloroethane (DCE) interface has been studied. The water|DCE interface essentially acts as a proton pump controlled by the Galvani potential difference across the interface, driving the proton transfer from water to DCE. [Co(tpp)] catalyzed O(2) reduction by Fc, DFc and DMFc is then followed to produce hydrogen peroxide (H(2)O(2)). The catalytic mechanism is similar to that proposed by Fukuzumi et al. for bulk reactions. This interfacial system provides a platform for a very efficient collection of H(2)O(2), by extraction immediately after its formation in DCE to the adjacent water phase, thus decreasing the possibility of degradation and further reaction with ferrocene derivatives.