Catalytic formation of hydrogen peroxide from coenzyme NADH and dioxygen with a water-soluble iridium complex and a ubiquinone coenzyme analogue

Tomoyoshi Suenobu, Satoshi Shibata, Shunichi Fukuzumi

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Abstract

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: [IrIII(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.

Original languageEnglish
Pages (from-to)7747-7754
Number of pages8
JournalInorganic Chemistry
Volume55
Issue number15
DOIs
StatePublished - 1 Aug 2016

Bibliographical note

Funding Information:
This work was supported by ALCA and SENTAN projects from JST (to S.F.) and JSPS KAKENHI (Grant No. 16H02268 to S.F. and No. 16K05721 to T.S.), Japan.

Publisher Copyright:
© 2016 American Chemical Society.

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