Phenazine-Photosensitized Reduction of CO2 Mediated by a Cobalt-Cyclam Complex through Electron and Hydrogen Transfer

Ogata, Tomoyuki; Yamamoto, Yoshie; Wada, Yuji; Murakoshi, Kei; Kusaba, Mitsuhiro; Nakashima, Nobuaki; Ishida, Akihiro; Takamuku, Setsuo; Yanagida, Shozo

doi:10.1021/j100031a020

Cited by 99 publications

(94 citation statements)

References 8 publications

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“…Hydrogen evolution was also observed in the absence of CO 2 . The sensitization process is thought to occur via a phenazine radical anion formed by the reaction of the excited phenazine molecule in its triplet state with TEA and is able to reduce Co(III) to Co(II) [45].…”

Section: Cobalt Cyclam Porphyrin and Corrin Complexesmentioning

confidence: 99%

Catalytic hydrogen production at cobalt centres

Losse

Vos

Rau

2010

Coordination Chemistry Reviews

295

222

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Section: Cobalt Cyclam Porphyrin and Corrin Complexesmentioning

confidence: 99%

Catalytic hydrogen production at cobalt centres

Losse

Vos

Rau

2010

Coordination Chemistry Reviews

295

222

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“…Only a few photocatalysts for the selective formation of formic acid from CO 2 have been reported (3)(4)(5)(6)(7)(8). Although oligo(p-phenylenes) (3) or a mixed system of phenazine and Co cyclam (4) successfully photocatalyzed the reduction of CO 2 to formic acid, these systems cannot work with visible light.…”

mentioning

confidence: 99%

“…Although oligo(p-phenylenes) (3) or a mixed system of phenazine and Co cyclam (4) successfully photocatalyzed the reduction of CO 2 to formic acid, these systems cannot work with visible light. It has been reported that ½RuðbpyÞ 2 ðCOÞ 2 2þ (bpy ¼ 2,2′-bipyridine) acted as a catalyst for reducing CO 2 (5)(6)(7)(8).…”

mentioning

confidence: 99%

Photocatalytic CO ₂ reduction with high turnover frequency and selectivity of formic acid formation using Ru(II) multinuclear complexes

Tamaki

Morimoto

Koike

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

304

238

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Previously undescribed supramolecules constructed with various ratios of two kinds of Ru(II) complexes-a photosensitizer and a catalyst-were synthesized. These complexes can photocatalyze the reduction of CO 2 to formic acid with high selectivity and durability using a wide range of wavelengths of visible light and NADH model compounds as electron donors in a mixed solution of dimethylformamide-triethanolamine. Using a higher ratio of the photosensitizer unit to the catalyst unit led to a higher yield of formic acid. In particular, of the reported photocatalysts, a trinuclear complex with two photosensitizer units and one catalyst unit photocatalyzed CO 2 reduction (Φ HCOOH ¼ 0.061, TON HCOOH ¼ 671) with the fastest reaction rate (TOF HCOOH ¼ 11.6 min −1 ). On the other hand, photocatalyses of a mixed system containing two kinds of model mononuclear Ru(II) complexes, and supramolecules with a higher ratio of the catalyst unit were much less efficient, and black oligomers and polymers were produced from the Ru complexes during photocatalytic reactions, which reduced the yield of formic acid. The photocatalytic formation of formic acid using the supramolecules described herein proceeds via two sequential processes: the photochemical reduction of the photosensitizer unit by NADH model compounds and intramolecular electron transfer to the catalyst unit. R ecently, global warming and shortages of fossil fuels and carbon resources have become serious issues. The development of technologies to convert CO 2 into useful organic compounds using sunlight as an energy source would serve as an ideal solution to these problems.Formic acid, which is the two-electron reduction product of CO 2 , has recently attracted attention as a storage source of H 2 (1, 2). Formic acid itself is an important chemical. It has been employed as a preservative and an insecticide and is also a useful acid, reducing agent, and source of carbon in synthetic chemical industries.Only a few photocatalysts for the selective formation of formic acid from CO 2 have been reported (3-8). Although oligo(p-phenylenes) (3) or a mixed system of phenazine and Co cyclam (4) successfully photocatalyzed the reduction of CO 2 to formic acid, these systems cannot work with visible light. It has been reported that ½RuðbpyÞ 2 ðCOÞ 2 2þ (bpy ¼ 2,2′-bipyridine) acted as a catalyst for reducing CO 2 (5-8). Under basic conditions, a mixed system of this complex with ½RuðbpyÞ 3 2þ as a redox photosensitizer photocatalyzed the reduction of CO 2 to formic acid with high selectivity (6, 8). However, this photocatalytic system is limited by instability as evidenced by the fact that the catalyst decomposed following prolonged irradiation and generated black precipitates.We have recently developed a unique architecture for constructing visible-light-driven supramolecular photocatalysts, consisting of a ½RuðN ∧ NÞ 3 2þ (N ∧ N ¼ a diimine ligand)-type complex as a photosensitizer and a Re(I) diimine complex as a catalyst (9-12). These supramolecules can selectively photocatalyze ...

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“…In diesem Abschnitt werden wir zunächst Mehrkomponentensysteme aus isolierten Photosensibilisatoren und H 2 -erzeugenden Katalysatoren besprechen und dann zu supramolekularen Aggregaten übergehen, die beide Funktionen in sich vereinigen. Systeme, in denen die H 2 -Entwicklung nur als Nebenreaktion zur photochemischen CO 2 -Reduktion (oder gekoppelt mit diesem Prozess) auftritt, [111][112][113][114][115] [121,122] Cobaltkomplexe wurden in diesen Systemen ursprünglich alternativ zu Methylviologen [118,124,125] als Elektronenüberträger [123] eingesetzt. Kontrollexperimente zeigten dann aber, dass auch ohne den Pt-Katalysator Wasserstoff gebildet wurde.…”

Section: Cobalt In Der Photokatalytischen H 2 -Erzeugungunclassified

Wasserspaltung mit Cobalt

2011

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Die Energieversorgung der Zukunft kann nur durch grundlegende Neuerungen auf dem Gebiet billiger, nachhaltiger und effizienter Systeme zur Gewinnung und Speicherung von Energie aus erneuerbaren Quellen oder aus Sonnenlicht gesichert werden. Die Erzeugung von Wasserstoff, einem Brennstoff mit bemerkenswerten Eigenschaften, durch die Wasserspaltung mithilfe von Sonnenlicht ist in diesem Zusammenhang ein vielversprechender Ansatz. Während die aktiven Zentren von wasserspaltenden Enzymen – wie Hydrogenasen und Photosystem II – Eisen‐, Nickel‐ und Manganionen enthalten, hat sich Cobalt in den vergangenen fünf Jahren als vielseitigstes unedles Metall bei der Entwicklung synthetischer Katalysatoren zur H2‐ und O2‐Erzeugung durch Reduktion bzw. Oxidation von Wasser bewährt. Solche Katalysatoren lassen sich mit Photosensibilisatoren zu Systemen für die photokatalytische Wasserstofferzeugung aus Wasser koppeln.

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Phenazine-Photosensitized Reduction of CO2 Mediated by a Cobalt-Cyclam Complex through Electron and Hydrogen Transfer

Cited by 99 publications

References 8 publications

Catalytic hydrogen production at cobalt centres

Catalytic hydrogen production at cobalt centres

Photocatalytic CO ₂ reduction with high turnover frequency and selectivity of formic acid formation using Ru(II) multinuclear complexes

Wasserspaltung mit Cobalt

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Phenazine-Photosensitized Reduction of CO2 Mediated by a Cobalt-Cyclam Complex through Electron and Hydrogen Transfer

Cited by 99 publications

References 8 publications

Catalytic hydrogen production at cobalt centres

Catalytic hydrogen production at cobalt centres

Photocatalytic CO 2 reduction with high turnover frequency and selectivity of formic acid formation using Ru(II) multinuclear complexes

Wasserspaltung mit Cobalt

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Photocatalytic CO ₂ reduction with high turnover frequency and selectivity of formic acid formation using Ru(II) multinuclear complexes