Homogeneous catalysis of dioxygen reduction by molecular Mn complexes

Cook, Emma N.; Machan, Charles W.

doi:10.1039/d2cc04628h

Cited by 12 publications

(19 citation statements)

References 149 publications

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“…Substantial enhancement of the cathodic current was observed at this potential under 1 atm O 2 in the presence of acetic acid (AcOH) (Fig. 2B, blue trace a ), resembling studies of ORR electrocatalysis with molecular Mn complexes ( 23 – 26 ). The addition of Ph 2 S to this reaction mixture suppressed the catalytic current (Fig.…”

Section: Cathodic Monooxygenase Activitysupporting

confidence: 64%

Synthetic dioxygenase reactivity by pairing electrochemical oxygen reduction and water oxidation

Hoque,

Gerken,

Stahl

2024

Science

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The reactivity of molecular oxygen is crucial to clean energy technologies and green chemical synthesis, but kinetic barriers complicate both applications. In synthesis, dioxygen should be able to undergo oxygen atom transfer to two organic molecules with perfect atom economy, but such reactivity is rare. Monooxygenase enzymes commonly reductively activate dioxygen by sacrificing one of the oxygen atoms to generate a more reactive oxidant. Here, we used a manganese-tetraphenylporphyrin catalyst to pair electrochemical oxygen reduction and water oxidation, generating a reactive manganese-oxo at both electrodes. This process supports dioxygen atom transfer to two thioether substrate molecules, generating two equivalents of sulfoxide with a single equivalent of dioxygen. This net dioxygenase reactivity consumes no electrons but uses electrochemical energy to overcome kinetic barriers.

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Section: Cathodic Monooxygenase Activitysupporting

confidence: 64%

Synthetic dioxygenase reactivity by pairing electrochemical oxygen reduction and water oxidation

Hoque,

Gerken,

Stahl

2024

Science

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“…Structure of Mn( tbu dhbpy)Cl catalyst developed in our lab, where ( tbu dhbpy)(H) 2 is 6,6′-di(3,5-di- tert -butyl-2-hydroxybenzene)-2,2′-bipyridine, and summary of results in ref . Reproduced from ref with permission from the Royal Society of Chemistry.…”

Section: Recent Examples Of Redox Mediators In Homogeneous Co-electro...mentioning

confidence: 99%

Redox Mediators in Homogeneous Co-electrocatalysis

Reid

Machan

2023

J. Am. Chem. Soc.

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Homogeneous electrocatalysis has been well studied over the past several decades for the conversion of small molecules to useful products for green energy applications or as chemical feedstocks. However, in order for these catalyst systems to be used in industrial applications, their activity and stability must be improved. In naturally occurring enzymes, redox equivalents (electrons, often in a concerted manner with protons) are delivered to enzyme active sites by small molecules known as redox mediators (RMs). Inspired by this, co-electrocatalytic systems with homogeneous catalysts and RMs have been developed for the conversion of alcohols, nitrogen, unsaturated organic substrates, oxygen, and carbon dioxide. In these systems, the RMs have been shown to both increase the activity of the catalyst and shift selectivity to more desired products by altering catalytic cycles and/or avoiding high-energy intermediates. However, the area is currently underdeveloped and requires additional fundamental advancements in order to become a more general strategy. Here, we summarize the recent examples of homogeneous coelectrocatalysis and discuss possible future directions for the field.

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“…[ 15‐17 ] Macrocyclic complexes with the classical M‐N 4 model are an intriguing family of catalysts that show great promise in this regard. [ 18‐20 ] Therefore, diverse molecular complexes of first‐row transition metal elements, including Mn, [ 21‐23 ] Fe, [ 24‐26 ] Co, [ 27‐29 ] Ni, [ 30‐32 ] and Cu, [ 33‐35 ] have been proven to be efficient ORR electrocatalysts. Basic knowledge of the structure‐function relationships is obtained by studying these molecular catalysts.…”

Section: Background and Originality Contentmentioning

confidence: 99%

A Cobalt(III) Corrole with a Tethered Imidazole for Boosted Electrocatalytic Oxygen Reduction Reaction

Peng

Luo

2023

Chin. J. Chem.

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Comprehensive SummaryDeveloping electrocatalysts with high activity and selectivity for the oxygen reduction reaction (ORR) is vital to promote the performance of the next‐generation energy technologies, which depend on the efficiency of the catalytic reduction of dioxygen. In the structure of cytochrome c oxidases (CcOs), a histidine imidazole residue binding to the axial position of Fe plays a crucial role in facilitating the selective reduction of O2 to water. Inspired by nature, we herein report on the synthesis of CoIII corrole 1 tethered with an imidazole ligand as well as its electrocatalytic ORR and O2 binding features. As compared to the imidazolium‐free analogue, complex 1 displayed remarkably boosted activity for the selective four‐electron/four‐proton (4e‐/4H+) ORR with a half‐wave potential of E1/2 = 0.82 V versus reversible hydrogen electrode (RHE) in 0.1 mol/L KOH solutions. Importantly, we demonstrate that the tethered axial imidazole ligand improves the O2 binding ability of 1 thermodynamically and dynamically, which is crucial to boost electrocatalytic ORR performance. This work presents an example to improve electrocatalytic ORR activity and selectivity of Co corroles by introducing an axial imidazole ligand to enhance the O2 binding and activation.

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Homogeneous catalysis of dioxygen reduction by molecular Mn complexes

Abstract: Continually increasing global energy demand perpetuates the need for effective alternative energy sources and ‘green’ industrial processes. The oxygen reduction reaction (ORR) is crucial to the development of hydrogen fuel...

Cited by 12 publications

References 149 publications

Synthetic dioxygenase reactivity by pairing electrochemical oxygen reduction and water oxidation

Synthetic dioxygenase reactivity by pairing electrochemical oxygen reduction and water oxidation

Redox Mediators in Homogeneous Co-electrocatalysis

A Cobalt(III) Corrole with a Tethered Imidazole for Boosted Electrocatalytic Oxygen Reduction Reaction

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