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Acid-induced mechanism change and overpotential decrease in dioxygen reduction catalysis with a dinuclear copper complex

Title
Acid-induced mechanism change and overpotential decrease in dioxygen reduction catalysis with a dinuclear copper complex
Authors
Das D.Lee Y.-M.Ohkubo K.Nam W.Karlin K.D.Fukuzumi S.
Ewha Authors
남원우Shunichi Fukuzumi이용민Kenneth D. Karlin
SCOPUS Author ID
남원우scopus; Shunichi Fukuzumiscopus; 이용민scopusscopus
Issue Date
2013
Journal Title
Journal of the American Chemical Society
ISSN
0002-7863JCR Link
Citation
Journal of the American Chemical Society vol. 135, no. 10, pp. 4018 - 4026
Indexed
SCI; SCIE; SCOPUS WOS scopus
Document Type
Article
Abstract
Catalytic four-electron reduction of O2 by ferrocene (Fc) and 1,1′-dimethylferrocene (Me2Fc) occurs efficiently with a dinuclear copper(II) complex [CuII 2(XYLO)(OH)] 2+ (1), where XYLO is a m-xylene-linked bis[(2-(2-pyridyl)ethyl) amine] dinucleating ligand with copper-bridging phenolate moiety], in the presence of perchloric acid (HClO4) in acetone at 298 K. The hydroxide and phenoxo group in [CuII 2(XYLO)(OH)] 2+ (1) undergo protonation with HClO4 to produce [Cu II 2(XYLOH)]4+ (2) where the two copper centers become independent and the reduction potential shifts from -0.68 V vs SCE in the absence of HClO4 to 0.47 V; this makes possible the use of relatively weak one-electron reductants such as Fc and Me2Fc, significantly reducing the effective overpotential in the catalytic O 2-reduction reaction. The mechanism of the reaction has been clarified on the basis of kinetic studies on the overall catalytic reaction as well as each step in the catalytic cycle and also by low-temperature detection of intermediates. The O2-binding to the fully reduced complex [CuI 2(XYLOH)]2+ (3) results in the reversible formation of the hydroperoxo complex ([CuII 2(XYLO)(OOH)] 2+) (4), followed by proton-coupled electron-transfer (PCET) reduction to complete the overall O2-to-2H2O catalytic conversion. © 2013 American Chemical Society.
DOI
10.1021/ja312256u
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자연과학대학 > 화학·나노과학전공 > Journal papers
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