Oxidation of copper(II) hydroxyporphyrin (oxophlorin); oxidative ring opening and formation of an ester-linked, dinuclear copper complex
2001; NRC Research Press; Volume: 79; Issue: 5-6 Linguagem: Inglês
10.1139/v01-042
ISSN1480-3291
AutoresShane L. Phillips, B.C. Noll, Marilyn M. Olmstead, Alan L. Balch,
Tópico(s)Hemoglobin structure and function
ResumoAddition of copper(II) acetate to octaethyl(meso-hydroxy)porphyrin (H 2 OEPOH) in THF under a dinitrogen atmosphere produces Cu II (OEPOH), which has been isolated as red crystals and shown to have a meso-hydroxyporphyrin structure by UV-vis and EPR spectroscopy. Cu II (OEPOH) undergoes oxidation by dioxygen to form a novel dinuclear copper complex {Cu II (OEPOC(O)OEB)Cu II }. This dinuclear complex is composed of a copper(II) meso-substituted porphyrin portion (with a planar CuN 4 unit), which is attached through an ester linkage to a helical copper(II) tetrapyrrole that has been ring-opened through oxidative cleavage of a second molecule of Cu II (OEPOH). The oxidative ring-opening reaction resembles that of natural heme catabolism but is arrested at a stage where the oxidized meso-carbon is still appended to the helical open tetrapyrrole. A mechanism is suggested for this process.Key words: copper porphyrin, crystal structure, porphyrin oxidation, linear tetrapyrrole, hydroxy-porphyrin, oxophlorin.
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