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Iron Porphyrins as Models of Cytochrome c Oxidase

Abstract : A series of iron porphyrins has been synthesized as models of cytochrome c oxidase; their activity as 4 e-catalysts in the reduction of dioxygen has been studied at pH 7. These compounds have been obtained by grafting very different residues onto the same iron complex, namely tripodal tetraamines, pickets, and straps, in order to change the environment of the metal center. In the case of porphyrins bearing a tripodal cap, the secondary amines have been alkylated with different substituents so as to modify the electronic environment of the distal pocket. Surprisingly, when the iron porphyrin is functionalized with four identical acrylamido pickets, the resulting complex exhibits biomimetic activity in that it catalyzes oxygen reduction with almost no production of hydrogen peroxide. The crystal structure of the redox-inactive zinc(ii) analogue is reported; this shows how the metal influences the spatial arrangement of the four pickets through axial coordination and hydrogen bonding. Even a bis-strapped iron porphyrin, for which no dimerization or self-aggregation can occur at the electrode surface, acts as a 4 eÿ catalyst for O2 reduction. It is thus demonstrated that at pH close to physiological values, the iron porphyrin is an intrinsically efficient catalyst for the reduction of oxygen to water.
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https://hal-univ-rennes1.archives-ouvertes.fr/hal-01469557
Contributor : Bernard Boitrel <>
Submitted on : Thursday, February 16, 2017 - 3:26:13 PM
Last modification on : Thursday, November 29, 2018 - 4:09:19 PM

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  • HAL Id : hal-01469557, version 1

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Bernard Boitrel, David Ricard, Philippe Richard, Maurice l'Her. Iron Porphyrins as Models of Cytochrome c Oxidase. Chemistry - A European Journal, Wiley-VCH Verlag, 2001, 7 (15), pp.3291-3297. ⟨hal-01469557⟩

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