Mechanistic aspects of the catalytic reduction of dioxygen by cofacial metalloporphyrins

Durand, Richard R.; Bencosme, C. Susana; Collman, James P.; Anson, Fred C.

doi:10.1021/ja00347a032

Cited by 287 publications

(150 citation statements)

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“…At this point, we can conclude that P 4+ adsorbs at the interface to carry out oxygen reduction with a selectivity of 50% for the four-electron pathway whereas [P ] toward the four-electron route, the three steps of the mechanism proposed for the four-electron reduction of oxygen by synthetic Pacman cofacial porphyrins must be considered: 1,5,8,50 (i) Oxygen is held in the cavity formed between the two porphyrins. 1,5,8,50 To determine whether in the complex [P 4+ /P…”

Section: Resultsmentioning

confidence: 99%

“…5 (iii) The protonation of the μ-superoxo complex is necessary to allow reduction. 1,5,8,50 Biphasic reactions between the porphyrins, the organic acid HTB (obtained by biphasic transfer between DCE and aqueous LiTB and HCl 28 ) and TTF were performed in absence of protons in the aqueous phase. The results showed that in all cases the reaction was as slow as when the reaction is performed by TTF alone, 28 indicating that in the interfacial reaction, the protonation of the μ-superoxo complex by aqueous protons is a key step to reach the catalytic effect and provide more evidence that the reaction is interfacial.…”

Section: Comentioning

confidence: 99%

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Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

et al. 2011

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ABSTRACT:The self-assembly of the oppositely charged watersoluble porphyrins, cobalt tetramethylpyridinium porphyrin (CoTMPyP 4+ ) and cobalt tetrasulphonatophenyl porphyrin (CoTPPS 4− ), at the interface with an organic solvent to form molecular "rafts", provides an excellent catalyst to perform the interfacial four-electron reduction of oxygen by lipophilic electron donors such as tetrathiafulvalene (TTF). The catalytic activity and selectivity of the self-assembled catalyst toward the four-electron pathway was found to be as good as that of the Pacman type cofacial cobalt porphyrins. The assembly has been characterized by UV−visible spectroscopy, Surface Second Harmonic Generation, and Scanning Electron Microscopy. Density functional theory calculations confirm the possibility of formation of the catalytic CoTMPyP 4+ / CoTPPS 4− complex and its capability to bind oxygen.

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Section: Resultsmentioning

confidence: 99%

Section: Comentioning

confidence: 99%

Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

et al. 2011

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“…[13][14][15] In most cases, monomeric cobalt porphyrins catalyze the electroreduction of O 2 to hydrogen peroxide (H 2 O 2 ), whereas dimeric cofacial cobalt porphyrins demonstrate the catalysis of four-electron reduction of O 2 to water. [3,7,8,10,12,15,16,[24][25][26][27] Employing ferrocene derivatives as electron donors, O 2 reduction catalyzed by various cobalt porphyrins has been investigated by Fukuzumi et al in organic media in the presence of HClO 4 . [13][14][15] In the reaction scheme, the steps of electron coordination to form a superoxide adduct and its reduction by ferrocene derivatives to produce H 2 O 2 /H 2 O and Co III are fast, and that of reducing Co III by ferrocene derivatives is slow and rate limiting.…”

Section: Introductionmentioning

confidence: 99%

Proton Pump for O₂ Reduction Catalyzed by 5,10,15,20‐Tetraphenylporphyrinatocobalt(II)

Partovi‐Nia

et al. 2009

Chemistry A European J

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Oxygen reduction: A polarized water|1,2‐dichloroethane (DCE) interface acts as a proton pump for the [Co(tpp)] (TPP=5,10,15,20‐tetraphenylporphyrinato) catalyzed O2 reduction by ferrocene (Fc) compounds to produce H2O2 (see figure; IT=ion transfer, ET=electron transfer). This system favours the collection of H2O2 by extraction immediately after its formation in DCE to the adjacent water phase.magnified imageThe role of 5,10,15,20‐tetraphenylporphyrinatocobalt(II) ([Co(tpp)]) as a catalyst on molecular oxygen (O2) reduction by ferrocene (Fc) and its two derivatives, 1,1′‐dimethylferrocene (DFc) and decamethylferrocene (DMFc) at a polarized water|1,2‐dichloroethane (DCE) interface has been studied. The water|DCE interface essentially acts as a proton pump controlled by the Galvani potential difference across the interface, driving the proton transfer from water to DCE. [Co(tpp)] catalyzed O2 reduction by Fc, DFc and DMFc is then followed to produce hydrogen peroxide (H2O2). The catalytic mechanism is similar to that proposed by Fukuzumi et al. for bulk reactions. This interfacial system provides a platform for a very efficient collection of H2O2, by extraction immediately after its formation in DCE to the adjacent water phase, thus decreasing the possibility of degradation and further reaction with ferrocene derivatives.

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“…124 Outstanding research in this area has been carried out by Anson and co-workers along the last twenty years. [125][126][127] Collman and co-workers [128][129][130][131] have shown that the simultaneous interaction of the O 2 molecule with two CoP centers is involved in the activation by a cofacial biscobaltporphyrin. However, more recently, they found out that the change of the electrode material from pyrolytic graphite to gold can switch the mechanism from tetraelec- 6,2003 tronic to bielectronic.…”

Section: Multielectron Transfer Catalysis By Supramolecular Films Of mentioning

confidence: 99%

Molecular Materials and Devices: Developing New Functional Systems Based on the Coordination Chemistry Approach

Toma

2004

ChemInform

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Neste limiar da era nanotecnológica, o planejamento molecular dos materiais e os estudos de moléculas isoladas estão abrindo imensas possibilidades no emprego de sistemas moleculares em dispositivos eletrônicos e fotônicos, bem como em aplicações tecnológicas baseadas em propriedades de chaveamento ou reconhecimento molecular. Com esse escopo, os químicos inorgânicos em particular, podem aplicar com vantagens as estratégias proporcionadas pela química de coordenação, para construir nanomateriais funcionais que permitam a exploração das propriedades dos centros metálicos e das características dos ligantes presentes. A química de coordenação também oferece recursos eficientes na auto-montagem de nanoestruturas, baseadas na especificidade da interação metal-ligante e nas características estereoquímicas dos complexos. Diversos materiais moleculares gerados a partir de compostos inorgânicos e metal-orgânicos são focalizados neste artigo, com ênfase em novas porfirinas e porfirazinas supramoleculares, clusters e complexos metálicos. Tais sistemas também são enfocados sob o ponto de vista de suas aplicações em catálise, sensores e dispositivos moleculares.At the onset of the nanotechnology age, molecular designing of materials and single molecule studies are opening wide possibilities of using molecular systems in electronic and photonic devices, as well as in technological applications based on molecular switching or molecular recognition. In this sense, inorganic chemists are privileged by the possibility of using the basic strategies of coordination chemistry to build up functional supramolecular materials, conveying the remarkable chemical properties of the metal centers and the characteristics of the ancillary ligands. Coordination chemistry also provides effective self-assembly strategies based on specific metal-ligand affinity and stereochemistry. Several molecular based materials, derived from inorganic and metal-organic compounds are focused on this article, with emphasis on new supramolecular porphyrins and porphyrazines, metal-clusters and metal-polyimine complexes. Such systems are also discussed in terms of their applications in catalysis, sensors and molecular devices.

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Mechanistic aspects of the catalytic reduction of dioxygen by cofacial metalloporphyrins

Cited by 287 publications

References 1 publication

Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

Proton Pump for O₂ Reduction Catalyzed by 5,10,15,20‐Tetraphenylporphyrinatocobalt(II)

Molecular Materials and Devices: Developing New Functional Systems Based on the Coordination Chemistry Approach

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Mechanistic aspects of the catalytic reduction of dioxygen by cofacial metalloporphyrins

Cited by 287 publications

References 1 publication

Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

Proton Pump for O2 Reduction Catalyzed by 5,10,15,20‐Tetraphenylporphyrinatocobalt(II)

Molecular Materials and Devices: Developing New Functional Systems Based on the Coordination Chemistry Approach

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Proton Pump for O₂ Reduction Catalyzed by 5,10,15,20‐Tetraphenylporphyrinatocobalt(II)