Inorganic Chemistry, Vol.45, No.26, 10750-10757, 2006
Built-in axial base binding on phenanthroline-strapped zinc(II) and iron(III) porphyrins
In addition to the need for functional models of cytochrome c oxidase, structural models are still required for a better understanding of the small reorganizations occurring during the catalytic cycle. An efficient synthetic approach has been designed to prepare several phenanthroline-strapped porphyrins, two of them bearing two pendant imidazoles. These built-in bases are both potentially able to act as axial bases for the metalloporphyrin and as complementary ligands for copper if necessary. Diamagnetic zinc(II) was used to demonstrate that the distal/proximal selectivity demonstrated by exogenic bases binding studies can be extended to the coordination of iron(III). Combination of EPR and paramagnetic H-1 NMR shows that the imidazole binding on the zinc species can be further extended to the iron(III) species in dilute conditions.