Catalytic Formation of Hydrogen Peroxide from Coenzyme NADH and Dioxygen with a Water-Soluble Iridium Complex and a Ubiquinone Coenzyme Analogue

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• 作者：Tomoyoshi Suenobu ; Satoshi Shibata ; Shunichi Fukuzumi
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：August 1, 2016
• 年：2016
• 卷：55
• 期：15
• 页码：7747-7754
• 全文大小：619K
• 年卷期：0
• ISSN：1520-510X

文摘

A ubiquinone coenzyme analogue (Q₀: 2,3-dimethoxy-5-methyl-1,4-benzoquinone) was reduced by coenzyme NADH to yield the corresponding reduced form of Q₀ (Q₀H₂) in the presence of a catalytic amount of a [C,N] cyclometalated organoiridium complex (1: [Ir^III(Cp*)(4-(1H-pyrazol-1-yl-κN²)benzoic acid-κC³)(H₂O)]₂SO₄) in water at ambient temperature as observed in the respiratory chain complex I (Complex I). In the catalytic cycle, the reduction of 1 by NADH produces the corresponding iridium hydride complex that in turn reduces Q₀ to produce Q₀H₂. Q₀H₂ reduced dioxygen to yield hydrogen peroxide (H₂O₂) under slightly basic conditions. Catalytic generation of H₂O₂ was made possible in the reaction of O₂ with NADH as the functional expression of NADH oxidase in white blood cells utilizing the redox cycle of Q₀ as well as 1 for the first time in a nonenzymatic homogeneous reaction system.