化学
铜
电子顺磁共振
二聚体
过氧化氢
金属
催化循环
结晶学
无机化学
半醌
催化作用
光化学
氧化还原
有机化学
核磁共振
物理
作者
María Rosa Mendoza-Quijano,Gerardo Ferrer‐Sueta,Marcos Flores‐Álamo,Núria Aliaga‐Alcalde,Virgínia Gómez-Vidales,Víctor M. Ugalde‐Saldívar,Laura Gasque
出处
期刊:Dalton Transactions
[The Royal Society of Chemistry]
日期:2012-01-01
卷期号:41 (16): 4985-4985
被引量:63
摘要
The catecholase activity of two dinuclear Cu(II) complexes with distant metal centers is discussed together with solid state and solution studies. The crystal structure for one of them, [Cu2(diep)(H2O)4](ClO4)4·2H2O, is described, showing the two copper ions are 7.457 Å apart and in a square pyramidal coordination. Both complexes display a weak antiferromagnetic coupling in the solid state that is manifest in the dimer EPR spectra obtained in frozen solution. The pH-potentiometric speciation performed in 1 : 1 MeOH–H2O allowed the assignment of hydrolyzed copper species as those catalytically active in the oxidation of 3,5-di-tert-butylcatechol (DTBC). The kinetic measurements led us to propose behavior consistent with Michaelis–Menten plus a linear dependence of the initial rate on [DTBC]. This can be associated with the presence of more than one catalytically active species, which is consistent with the evidence of several differently hydrolyzed species shown in the predominance diagrams. Product characterization studies led to establishing the formation of hydrogen peroxide during the catalytic cycle, while semiquinone and superoxide radicals were detected by EPR spectroscopy, supporting one-electron transference at each of the copper centers.
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