Picosecond photochemistry of a cofacial diporphyrin containing iron(III) and zinc(II): Mimicking electron transfer between cytochrome c and the primary electron donor in reaction centers of photosynthetic bacteria

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Abstract
Comparison of picosecond kinetic and spectroscopic data for Zn octaethylporphine and Fe(III)Cl octaethylporphine with that for Zn.sbd.Fe(III)Cl, a cofacial diporphyrin composed of a Zn porphyrin covalently bound to an Fe(III)Fe(III)Cl porphyrin with 2 chains of 5 atoms each, supports the assignment of a light-driven electron transfer (k > 1011 s-1) within Zn.sbd.Fe(III)Cl to form .**GRAPHIC**. The kinetics (k .apprxeq. 1010 s-1) and thermodynamics of the reverse electron transfer are compared to those of a similar electron transfer in bacterial photosynthesis, the reduction of an oxidized bacteriochlorophyll dimer, .**GRAPHIC**. by Fe(II)cytochrome c.