Journal Article10.1021/ACS.JPCB.7B06443
Influence of Proton Acceptors on the Proton-Coupled Electron Transfer Reaction Kinetics of a Ruthenium–Tyrosine Complex
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TL;DR: Comprehensive kinetics modeling allowed for deconvolution of complex kinetics and determination of rate constants for each elementary step, highlighting the influence that proton transfer driving force exerts on PCET reaction kinetics.
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Abstract: A polypyridyl ruthenium complex with fluorinated bipyridine ligands and a covalently bound tyrosine moiety was synthesized, and its photo-induced proton-coupled electron transfer (PCET) reactivity in acetonitrile was investigated with transient absorption spectroscopy. Using flash–quench methodology with methyl viologen as an oxidative quencher, a Ru3+ species is generated that is capable of initiating the intramolecular PCET oxidation of the tyrosine moiety. Using a series of substituted pyridine bases, the reaction kinetics were found to vary as a function of proton acceptor concentration and identity, with no significant H/D kinetic isotope effect. Through analysis of the kinetics traces and comparison to a control complex without the tyrosine moiety, PCET reactivity was found to proceed through an equilibrium electron transfer followed by proton transfer (ET-PT) pathway in which irreversible deprotonation of the tyrosine radical cation shifts the ET equilibrium, conferring a base dependence on the rea...
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Citations
Molecular Cobalt Catalysts for O2 Reduction to H2O2: Benchmarking Catalyst Performance via Rate–Overpotential Correlations
TL;DR: In this paper, a homogeneous ORR catalyzed by cobalt macrocycles typically leads to selective 2e/2H+ reduction of O2 to H2O2; however, variations in the reaction conditions make it difficult to compare the performa...
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Photochemical tyrosine oxidation with a hydrogen-bonded proton acceptor by bidirectional proton-coupled electron transfer
Arturo A. Pizano,Jay L. Yang,Daniel G. Nocera +2 more
- 01 May 2012
TL;DR: Time-resolved studies establish that excited-state quenching occurs by a combination of static and dynamic mechanisms, consistent with a proton-coupled electron transfer (PCET) quenched mechanism.
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Visible-Light-Mediated Iminyl Radical Generation from Benzyl Oxime Ether: Synthesis of Pyrroline via Hydroimination Cyclization.
TL;DR: Mechanistic studies indicate that iminyl radical generation mainly proceeds by hydrogen abstraction of the photocatalyst from the benzyl position of the oxime.
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Recent advances in bioinspired proton-coupled electron transfer
Andrea Pannwitz,Oliver S. Wenger +1 more
TL;DR: 16 mechanistic PCET studies published over the past 5 years that contributed significantly to understanding and controlling PCET in artificial systems are discussed, including bio-inspired work on tyrosine-Z mimics, reactions involving the transfer of multiple protons, de novo designed proteins with very long-lived tyrosyl radicals, and PCETIn artificial DNA systems.
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Tuning Radical Relay Residues by Proton Management Rescues Protein Electron Hopping.
TL;DR: This work probes the redox properties of CcP Y191 by non-natural amino acid substitution, altering the ET driving force, and manipulating the protic environment of Y191 to find implications for the YZ/YD radicals of PS II, hole-hopping in RNR and cryptochrome, and engineering proteins for long-range ET reactions.
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TL;DR: Proton-coupled electron transfer is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues and several are reviewed.
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Thermochemistry of Proton-Coupled Electron Transfer Reagents and its Implications
TL;DR: This issue discusses proton-coupled electron transfer or PCET processes, which are central to a great many chemical and biochemical processes, from biological catalysis and energy transduction, to bulk industrial chemical processes, to new approaches to solar energy conversion.
Theoretical relations among rate constants, barriers, and Broensted slopes of chemical reactions
TL;DR: In this paper, a simple relation, ΔF* = (λ(1 + Δ/λ)^2)/4, was explored in a slightly modified version for reactions with considerable resonance splitting, such as atom transfers, proton transfers, and strong-overlap electron transfers.
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