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Catalytic two-electron reduction of dioxygen catalysed by metal-free [14]triphyrin(2.1.1)

Title
Catalytic two-electron reduction of dioxygen catalysed by metal-free [14]triphyrin(2.1.1)
Authors
Mase, KentaroOhkubo, KeiXue, ZhaoliYamada, HirokoFukuzumi, Shunichi
Ewha Authors
Shunichi FukuzumiKei Okubo
SCOPUS Author ID
Shunichi Fukuzumiscopus; Kei Okuboscopus
Issue Date
2015
Journal Title
CHEMICAL SCIENCE
ISSN
2041-6520JCR Link2041-6539JCR Link
Citation
vol. 6, no. 11, pp. 6496 - 6504
Publisher
ROYAL SOC CHEMISTRY
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
The catalytic two-electron reduction of dioxygen (O-2) by octamethylferrocene (Me(8)Fc) occurs with a metal-free triphyrin (HTrip) in the presence of perchloric acid (HClO4) in benzonitrile (PhCN) at 298 K to yield Me(8)Fc(+) and H2O2. Detailed kinetic analysis has revealed that the catalytic two-electron reduction of O-2 by Me(8)Fc with HTrip proceeds via proton-coupled electron transfer from Me(8)Fc to HTrip to produce H(3)Tripc(center dot+), followed by a second electron transfer from Me(8)Fc to H(3)Tripc(center dot+) to produce H(3)Trip, which is oxidized by O-2 via formation of the H(3)Trip/O-2 complex to yield H2O2. The rate-determining step in the catalytic cycle is hydrogen atom transfer from H(3)Trip to O-2 in the H(3)Trip/O-2 complex to produce the radical pair (H(3)Tripc(center dot+) HO(2)c) as an intermediate, which was detected as a triplet EPR signal with fine-structure by the EPR measurements at low temperature. The distance between the two unpaired electrons in the radical pair was determined to be 4.9 angstrom from the zero-field splitting constant (D).
DOI
10.1039/c5sc02465j
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자연과학대학 > 화학·나노과학전공 > Journal papers
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