Functional analogues of the so‐called Fea3–CuB active site of cytochrome  c oxidase were synthesized to elucidate the mechanism of the reduction of O2 to H2O. The role of each individual structural component, especially the CuB center, for catalytic activity was investigated. These quinolinoyl picket iron porphyrins (see picture) were shown to be efficient catalysts for the 4 e− reduction of dioxygen to water with or without a Cu ion in their distal site, clearly demonstrating that the Cu center is not essential for the catalytic activity.

The condensation of 3‐(chloromethyl)benzoyl chloride with different atropisomers of meso‐(tetra‐o‐aminophenyl)porphyrin (TAPP), followed by the reaction of a series of nucleophilic reagents leads, among others, to precursors of biomimetic models of heme proteins such as cytochrome c oxidase (CcO). This synthesis can also be applied as an efficient two‐step reaction to obtain highly functionalized porphyrin derivatives potentially useful for cation binding.

Tris(2-aminoethylamine) (tren)-capped porphyrins bearing electron donating or withdrawing groups on the amino functions of their tripod have been synthesised and the catalytic activity of each complex was carefully studied both as the iron and the iron-copper complexes: only one of our iron-copper complexes was shown to be active and selective towards the reduction of dioxygen to water.