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Homogeneous catalytic O 2 reduction to water by a cytochrome c oxidase model with trapping of intermediates and mechanistic insights

Title
Homogeneous catalytic O 2 reduction to water by a cytochrome c oxidase model with trapping of intermediates and mechanistic insights
Authors
Halime Z.Kotani H.Li Y.Fukuzumi S.Karlin K.D.
Ewha Authors
Shunichi FukuzumiKenneth D. Karlin
SCOPUS Author ID
Shunichi Fukuzumiscopus
Issue Date
2011
Journal Title
Proceedings of the National Academy of Sciences of the United States of America
ISSN
0027-8424JCR Link
Citation
vol. 108, no. 34, pp. 13990 - 13994
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
An efficient and selective four-electron plus four-proton (4e -?4H +) reduction of O 2 to water by decamethylferrocene and trifluoroacetic acid can be catalyzed by a synthetic analog of the heme a 3?Cu B site in cytochrome c oxidase ( 6LFeCu) or its Cu-free version ( 6LFe) in acetone. A detailed mechanistic-kinetic study on the homogeneous catalytic system reveals spectroscopically detectable intermediates and that the rate-determining step changes from the O 2-binding process at 25 °C room temperature (RT) to the O-O bond cleavage of a newly observed Fe III-OOH species at lower temperature (-60 °C). At RT, the rate of O 2-binding to 6LFeCu is significantly faster than that for 6LFe, whereas the rates of the O-O bond cleavage of the Fe III-OOH species observed (-60 ° C) with either the 6LFeCu or 6LFe catalyst are nearly the same. Thus, the role of the Cu ion is to assist the heme and lead to faster O 2-binding at RT. However, the proximate Cu ion has no effect on the O-O bond cleavage of the Fe III-OOH species at low temperature.
DOI
10.1073/pnas.1104698108
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자연과학대학 > 화학·나노과학전공 > Journal papers
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