Biochemistry and Theory of Proton-Coupled Electron Transfer

Chemical Reviews, Journal Year: 2014, Volume and Issue: 114(7), P. 3381 - 3465

Published: April 1, 2014

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTBiochemistry and Theory of Proton-Coupled Electron TransferAgostino Migliore*†, Nicholas F. Polizzi‡, Michael J. Therien†, David N. Beratan*†‡§View Author Information†Department Chemistry, ‡Department Biochemistry, §Department Physics, Duke University, Durham, North Carolina 27708, United States*Phone: 919-660-1556. E-mail: [email protected]*Phone: 919-660-1526. protected]Cite this: Chem. Rev. 2014, 114, 7, 3381–3465Publication Date (Web):April 1, 2014Publication History Received19 November 2013Published online1 April 2014Published inissue 9 2014https://doi.org/10.1021/cr4006654Copyright © 2014 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceArticle Views10346Altmetric-Citations308LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum full text article downloads since 2008 (both PDF HTML) across all institutions individuals. These metrics regularly updated to reflect usage leading up last few days.Citations number other articles citing this article, calculated by Crossref daily. Find more information about citation counts.The Altmetric Attention Score is a quantitative measure attention that research has received online. Clicking on donut icon will load page at altmetric.com with additional details score social media presence for given article. how calculated. Share Add toView InAdd Full Text ReferenceAdd Description ExportRISCitationCitation abstractCitation referencesMore Options onFacebookTwitterWechatLinked InReddit (14 MB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting SUBJECTS:Free energy,Charge transfer,Proton coupled electron transfer,Wave function,Solvents e-Alerts

Language: Английский

---

Thermal Hydrogen‐Atom Transfer from Methane: The Role of Radicals and Spin States in Oxo‐Cluster Chemistry

Angewandte Chemie International Edition, Journal Year: 2012, Volume and Issue: 51(23), P. 5544 - 5555

Published: March 16, 2012

Abstract Hydrogen‐atom transfer (HAT), as one of the fundamental reactions in chemistry, is investigated with state‐of‐the‐art gas‐phase experiments conjunction computational studies. The focus this Minireview concerns role that intrinsic properties gaseous oxo‐clusters play to permit HAT reactivity from saturated hydrocarbons at ambient conditions. In addition, mechanistic implications are discussed which pertain heterogeneous catalysis. From these combined experimental/computational studies, crucial unpaired spin density abstracting atom becomes clear, distinct contrast recent conclusions derived solution‐phase experiments.

Language: Английский

---

Proton-Coupled Electron Transfer in Solution, Proteins, and Electrochemistry

The Journal of Physical Chemistry B, Journal Year: 2008, Volume and Issue: 112(45), P. 14108 - 14123

Published: Oct. 9, 2008

Recent advances in the theoretical treatment of proton-coupled electron transfer (PCET) reactions are reviewed. These play an important role a wide range biological processes, as well fuel cells, solar chemical sensors, and electrochemical devices. A unified framework has been developed to describe both sequential concerted PCET, hydrogen atom (HAT). quantitative diagnostic proposed differentiate between HAT PCET terms degree electronic nonadiabaticity, where corresponds electronically adiabatic proton nonadiabatic transfer. In cases, overall reaction is typically vibronically nonadiabatic. series rate constant expressions have derived various limits by describing transitions electron−proton vibronic states. account for solvent response effects donor−acceptor vibrational motion. The protein environment can be represented dielectric continuum or described with explicit molecular dynamics. treatments applied numerous solution proteins. Expressions heterogeneous constants current densities also model systems.

Language: Английский

---

Proton-Coupled Electron Transfer: Moving Together and Charging Forward

Journal of the American Chemical Society, Journal Year: 2015, Volume and Issue: 137(28), P. 8860 - 8871

Published: June 25, 2015

Proton-coupled electron transfer (PCET) is ubiquitous throughout chemistry and biology. This Perspective discusses recent advances current challenges in the field of PCET, with an emphasis on role theory computation. The fundamental theoretical concepts are summarized, expressions for rate constants kinetic isotope effects provided. Computational methods calculating reduction potentials pKa's molecular electrocatalysts, as well insights into linear correlations non-innocent ligands, also described. In addition, computational simulating nonadiabatic dynamics photoexcited PCET discussed. Representative applications to solution, proteins, electrochemistry, photoinduced processes presented, highlighting interplay between experimental studies. suggested future directions outlined each type application, concluding overall view future.

Language: Английский

---

Electrocatalysis in Alkaline Media and Alkaline Membrane-Based Energy Technologies

Chemical Reviews, Journal Year: 2022, Volume and Issue: 122(6), P. 6117 - 6321

Published: Feb. 8, 2022

Hydrogen energy-based electrochemical energy conversion technologies offer the promise of enabling a transition global landscape from fossil fuels to renewable energy. Here, we present comprehensive review fundamentals electrocatalysis in alkaline media and applications alkaline-based technologies, particularly fuel cells water electrolyzers. Anion exchange (alkaline) membrane (AEMFCs) enable use nonprecious electrocatalysts for sluggish oxygen reduction reaction (ORR), relative proton (PEMFCs), which require Pt-based electrocatalysts. However, hydrogen oxidation (HOR) kinetics is significantly slower than acidic media. Understanding these phenomena requires applying theoretical experimental methods unravel molecular-level thermodynamics and, particularly, proton-coupled electron transfer (PCET) process that takes place proton-deficient Extensive spectroscopic studies, on single-crystal Pt metal oxides, have contributed development activity descriptors, as well identification nature active sites, rate-determining steps HOR ORR. Among these, structure reactivity interfacial serve key potential pH-dependent kinetic factors are helping elucidate origins ORR differences acids bases. Additionally, deliberately modulating controlling catalyst–support interactions provided valuable insights enhancing catalyst accessibility durability during operation. The design synthesis highly conductive durable membranes/ionomers enabled AEMFCs reach initial performance metrics equal or higher those PEMFCs. We emphasize importance using electrode assemblies (MEAs) integrate often separately pursued/optimized electrocatalyst/support membranes/ionomer components. Operando/in situ methods, at multiscales, ab initio simulations provide mechanistic understanding electron, ion, mass transport catalyst/ionomer/membrane interfaces necessary guidance achieve cell operation air over thousands hours. hope this Review will roadmap advancing scientific fundamental governing with ultimate goal achieving ultralow precious-metal-free high-performance related technologies.

Language: Английский

---

Theory of Proton-Coupled Electron Transfer in Energy Conversion Processes

Accounts of Chemical Research, Journal Year: 2009, Volume and Issue: 42(12), P. 1881 - 1889

Published: Oct. 7, 2009

Proton-coupled electron transfer (PCET) reactions play an essential role in a broad range of energy conversion processes, including photosynthesis and respiration. These also form the basis many types solar fuel cells electrochemical devices. Recent advances theory PCET enable prediction impact system properties on reaction rates. predictions may guide design more efficient catalysts for production, those based artificial conversion. This Account summarizes theoretically predicted dependence rates illustrates potential approaches tuning chemical systems. A general theoretical formulation has been developed over past decade. In this theory, are described terms nonadiabatic transitions between reactant product electron−proton vibronic states. series rate constant expressions both homogeneous have derived various well-defined limits. Recently extended to include effects solvent dynamics describe ultrafast interfacial PCET. Analysis provides insight into underlying physical principles enables system. Moreover, kinetic isotope effect, which is ratio hydrogen deuterium, useful mechanistic probe. Typically will increase as electronic coupling temperature total reorganization equilibrium proton donor−acceptor distance decrease. The driving force becomes negative, rather than exhibit turnover behavior inverted region, because excited states associated with low free barriers relatively large couplings become accessible. experimentally observed pH debated literature. When acceptor buffer species, arise from protonation buffer. It could complexity competing concerted sequential pathways. PCET, heterogeneous constants current densities depend strongly overpotential. change upon lead asymmetries Tafel plots deviations coefficient standard value one-half at zero Applications studied systems illustrate that can be utilized tune rate. For example, tuned by changing or using different species acceptors. site-specific mutagenesis biological modifications vary substituents redox Understanding these changes assist experimental efforts enhance processes.

Language: Английский

---

Recent Experimental Advances on Excited-State Intramolecular Proton Coupled Electron Transfer Reaction

Accounts of Chemical Research, Journal Year: 2010, Volume and Issue: 43(10), P. 1364 - 1374

Published: July 16, 2010

Proton-coupled electron transfer reactions form the basis of many important chemical processes including much energy conversion that occurs within living cells. However, physical chemistry underlies these reaction mechanisms remains poorly understood. In this Account, we report on recent progress in understanding excited-state intramolecular proton-coupled (PCET) reactions. The strategic design and synthesis various types PCET molecules, along with steady-state femtosecond time-resolved spectroscopy, have uncovered several solution. These experimental advancements correlate well current theoretical models, which proton has quantum motion a high probability tunneling. addition, rate is commonly incorporated rearrangement solvent molecules. As result, activation free essentially governed by reorganization because charge redistribution considered based polarity-induced barrier instead height migration barrier. accord basis, can rationalize observation for systems during relaxation time scale 1−10 ps: highly exergonic takes place before system reaches its equilibrium polarization. Also, used derivatives especially those 3-hydroxyflavone to clearly demonstrate how researchers tune dynamics through changes magnitude or direction dipole vector reaction. Subsequently, using 2-(2′-hydroxyphenyl)benzoxazole as parent model, then methods development an ideal probing Because future biomedical applications such will likely occur aqueous environments, discuss 7-azaindole analogues, requires assistance protic results provide unique contrast ubiquitous studies dynamic effects molecules undergo intrinsic motion.

Language: Английский

---

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 2017 - 2291

Published: Nov. 23, 2021

We present here a review of the photochemical and electrochemical applications multi-site proton-coupled electron transfer (MS-PCET) in organic synthesis. MS-PCETs are redox mechanisms which both an proton exchanged together, often concerted elementary step. As such, MS-PCET can function as non-classical mechanism for homolytic bond activation, providing opportunities to generate synthetically useful free radical intermediates directly from wide variety common functional groups. introduction practitioner’s guide reaction design, with emphasis on unique energetic selectivity features that characteristic this class. then chapters oxidative N–H, O–H, S–H, C–H homolysis methods, generation corresponding neutral species. Then, reductive PCET activations involving carbonyl, imine, other X═Y π-systems, heteroarenes, where ketyl, α-amino, heteroarene-derived radicals be generated. Finally, we asymmetric catalysis materials device applications. Within each chapter, subdivide by group undergoing homolysis, thereafter type transformation being promoted. Methods published prior end December 2020 presented.

Language: Английский

---

Dioxygen in Polyoxometalate Mediated Reactions

Chemical Reviews, Journal Year: 2017, Volume and Issue: 118(5), P. 2680 - 2717

Published: Dec. 1, 2017

In this review article, we consider the use of molecular oxygen in reactions mediated by polyoxometalates. Polyoxometalates are anionic metal oxide clusters a variety structures that soluble liquid phases and therefore amenable to homogeneous catalytic transformations. Often, they active for electron transfer oxidations myriad substrates upon reduction can be reoxidized oxygen. For example, phosphovanadomolybdate, H5PV2Mo10O40, oxidize Pd(0) thereby enabling aerobic catalyzed Pd H5PV2Mo10O40. similar vein, polyoxometalates stabilize nanoparticles, leading additional Furthermore, oxidation other such as halides sulfur-containing compounds is possible. More uniquely, H5PV2Mo10O40 its analogues mediate transfer-oxygen where atoms transferred from polyoxometalate substrate. This unique property has enabled correspondingly transformations involving carbon–carbon, carbon–hydrogen, carbon–metal bond activation. The pathway reoxidation vanadomolybdates with O2 appears an inner-sphere reaction, but one-electron reduced polyoxotungstates been shown through intensive research outer-sphere reaction. Beyond transfer–oxygen transformations, there few examples apparent dioxygenase activity both donated

Language: Английский

---

Hydrogen Tunneling Links Protein Dynamics to Enzyme Catalysis

Annual Review of Biochemistry, Journal Year: 2013, Volume and Issue: 82(1), P. 471 - 496

Published: June 2, 2013

The relationship between protein dynamics and function is a subject of considerable contemporary interest. Although motions are frequently observed during ligand binding release steps, the contribution to catalysis bond making/breaking processes more difficult probe verify. Here, we show how quantum mechanical hydrogen tunneling associated with enzymatic C-H cleavage provides unique window into necessity for achieving optimal catalysis. Experimental findings support hierarchy thermodynamically equilibrated that control H-donor -acceptor distance active-site electrostatics, creating an ensemble conformations suitable H-tunneling. A possible extension this view methyl transfer other catalyzed reactions also presented. impact understanding these on conceptual framework enzyme activity, inhibitor/drug design, biomimetic catalyst design likely be substantial.

Language: Английский

---