Spectroscopic properties of p/p and o/o type iron(III)-metal-free porphyrin dimers and their catalysis as Cytochrome P450 model
✍ Scribed by Qi-Zhi Ren; Jin-Wang Huang; Zhi-Ang Zhu; Liang-Nian Ji; Yun-Ti Chen
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 132 KB
- Volume
- 05
- Category
- Article
- ISSN
- 1088-4246
- DOI
- 10.1002/jpp.337
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✦ Synopsis
Two series of p/p and o/o type iron(III)-metal-free porphyrin dimers were synthesized and characterized. The dimers consist of a ferric porphyrin and a free-base porphyrin, covalently linked with an alkoxy chain - O ( CH ~2~)~n~ O -(n = 2–10) at the para and ortho position of two phenyl rings. The ferric paramagnetic effect and ring current effect on these dimers were discussed by ^1^ H NMR study; vibration modes sensitive to the conformations of the dimers were investigated from IR spectra; the electron density and spin state of ferric ion were examined using XPS and EPR spectroscopy. The catalytic activities of p/p and o/o type dimers on the hydroxylation of cyclohexane were studied under mild conditions. As a chemical mimic model of Cyto. P450, these porphyrins exhibit higher catalytic activities than the corresponding monomer FeTPPCl . With increase of the carbon numbers of alkoxy chain, the catalytic activity order of p/p dimers is C 2 < C 3 < C 4 < C 5 < C 6 > C 8 > C 10, the corresponding order of o/o dimers is C 2 > C 4 > C 6 > C 8 > C 10. Catalytic results of dimers are shown to strongly depend on their special conformation equilibrium, which affect the steric hindrance and electron transfer between two porphyrin rings.