Insight into copper coordination in O₂ reduction by water-soluble cytochrome c oxidase models

Iron-copper complexes have been extensively studied in the search for efficient cytochrome c oxidase models. Whereas most dinuclear materials usually focus on fine-tuning the coordination of heme-Fe, this work shows that the coordination of copper in cytochrome c oxidase models should be carefully taken into consideration. A β-cyclodextrin dimer was built around a bipyridine linker and combined with Fe-tetraphenylsulfonatoporphyrinate (FeTPPS) to generate a self-assembled hydrosoluble cytochrome c oxidase model. Cyclic voltammetry and rotating ring disk electrode experiments showed that this model with a tetrahedral coordination of copper(I) is efficient for the reduction of molecular oxygen with an average of 3.6 electrons indicating a preference and efficiency for the four-electron reduction to water.