Mononuclear Copper Complex-Catalyzed Four-Electron Reduction of Oxygen

Fukuzumi, Shunichi; Kotani, Hiroaki; Lucas, Heather R.; Doi, Kaoru; Suenobu, Tomoyoshi; Peterson, Ryan L.; Karlin, Kenneth D.

doi:10.1021/ja100538x

Cited by 132 publications

(131 citation statements)

References 27 publications

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“…2b). 35 The removal of potential oxidants (O 2 ˙− and H 2 O 2 ) by [(tmpa)Cu II ] 2+ led to improvement of the durability of the photocatalyst (Acr + –Mes) as shown in Figs 3 and 4.…”

Section: Resultsmentioning

confidence: 91%

Improvement of durability of an organic photocatalyst in p-xylene oxygenation by addition of a Cu(ii) complex

Yamada

Maeda

Ohkubo

et al. 2012

Phys. Chem. Chem. Phys.

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The catalytic durability of an organic photocatalyst, 9-mesityl-10-methyl acridinium ion (Acr+–Mes), has been dramatically improved by the addition of [{tris(2-pyridylmethyl)amine}-CuII](ClO4)2 ([(tmpa)CuII]2+) in the photocatalytic oxygenation of p-xylene by molecular oxygen in acetonitrile. Such an improvement is not observed by the addition of Cu(ClO4)2 in the absence of organic ligands. The addition of [(tmpa)Cu]2+ in the reaction solution resulted in more than an 11 times higher turnover number (TON) compared with the TON obtained without [(tmpa)CuII]2+. In the photocatalytic oxygenation, a stoichiometric amount of H2O2 formation was observed in the absence of [(tmpa)CuII]2+, however, much less H2O2 formation was observed in the presence of [(tmpa)CuII]2+. The photocatalytic mechanism was investigated by laser flash photolysis measurements in order to detect intermediates. The reaction of O2˙− with [(tmpa)CuII]2+ monitored by UV-vis spectroscopy in propionitrile at 203 K suggested formation of [{(tmpa)CuII}2O2]2+, a transformation which is crucial for the overall 4-electron reduction of molecular O2 to water, and a key in the observed improvement in the catalytic durability of Acr+–Mes.

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“…2b). 35 The removal of potential oxidants (O 2 ˙− and H 2 O 2 ) by [(tmpa)Cu II ] 2+ led to improvement of the durability of the photocatalyst (Acr + –Mes) as shown in Figs 3 and 4.…”

Section: Resultsmentioning

confidence: 91%

Improvement of durability of an organic photocatalyst in p-xylene oxygenation by addition of a Cu(ii) complex

Yamada

Maeda

Ohkubo

et al. 2012

Phys. Chem. Chem. Phys.

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“…The second-order rate constant ( k et ) of electron transfer from Fc* to [(L H )Cu II ] 2+ is 1.1 × 10 5 M −1 s −1 at 298 K [22]. The λ value is 1.29 eV by using Eqns.…”

Section: Kinetics and Thermodynamics Of Formation Of Cu-o2 Complexesmentioning

confidence: 99%

Kinetics and thermodynamics of formation and electron-transfer reactions of Cu–O2 and Cu2–O2 complexes

Fukuzumi

Karlin

2013

Coordination Chemistry Reviews

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The kinetics and thermodynamics of formation of Cu(II)-superoxo (Cu-O2) complexes by the reaction of Cu(I) complexes with dioxygen (O2) and the reduction of Cu(II)-superoxo complexes to dinuclear Cu-peroxo complexes are discussed. In the former case, electron transfer from a Cu(I) complex to O2 occurs concomitantly with binding of O2•− to the corresponding Cu(II) species. This is defined as an inner-sphere Cu(II) ion-coupled electron transfer process. Electron transfer from another Cu(I) complex to preformed Cu(II)-superoxo complexes also occurs concomitantly with binding of the the Cu(II)-peroxo species with the Cu(II) species to produce the dinuclear Cu-peroxo (Cu2-O2) complexes. The kinetics and thermodynamics of outer-sphere electron-transfer reduction of Cu2-O2 complexes are also been discussed in light of the Marcus theory of outer-sphere electron transfer.

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“…9,10 However, there are few studies in which intermediates formed during the reductive process have been characterized. The identity of reaction intermediates is often sought because they are helpful in elucidating the mechanisms and understanding the factors required for efficient and complete reduction of O 2 to H 2 O.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Reduction of Dioxygen to Water with a Monomeric Manganese Complex at Room Temperature

et al. 2011

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There have been numerous efforts to incorporate dioxygen into chemical processes because of its economic and environmental benefits. The conversion of dioxygen to water is one such example, having importance in both biology and fuel cell technology. Metals or metal complexes are usually necessary to promote this type of reaction and several systems have been reported. However, mechanistic insights into this conversion are still lacking, especially the detection of intermediates. Reported herein is the first example of a monomeric manganese(II) complex that can catalytically convert dioxygen to water. The complex contains a tripodal ligand with two urea groups and one carboxyamidopyridyl unit—this ligand creates an intramolecular hydrogen-bonding network within the secondary coordination sphere that aids in the observed chemistry. The manganese(II) complex is five-coordinate with an N4O primary coordination sphere; the oxygen donor comes from the deprotonated carboxyamido moiety. Two key intermediates were detected and characterized: a peroxo-manganese(III) species (1). The formulation of 1 was based on spectroscopic and analytical data, including an X-ray diffraction analysis. Reactivity studies showed dioxygen was catalytically converted to water in the presence of reductants, such as diphenylhydrazine and hydrazine. Water was confirmed as a product in greater than 90% yield. A mechanism was proposed that is consistent with the spectroscopy and product distribution, in which the carboxyamido group switches between a coordinated ligand and a basic site to scavenge protons produced during the catalytic cycle. These results highlight the importance of incorporating intramolecular functional groups within the secondary coordination sphere of metal-containing catalysts.

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Mononuclear Copper Complex-Catalyzed Four-Electron Reduction of Oxygen

Cited by 132 publications

References 27 publications

Improvement of durability of an organic photocatalyst in p-xylene oxygenation by addition of a Cu(ii) complex

Improvement of durability of an organic photocatalyst in p-xylene oxygenation by addition of a Cu(ii) complex

Kinetics and thermodynamics of formation and electron-transfer reactions of Cu–O2 and Cu2–O2 complexes

Catalytic Reduction of Dioxygen to Water with a Monomeric Manganese Complex at Room Temperature

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