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Depenbrock F, Limpke T, Bill E, SantaLucia DJ, van Gastel M, Walleck S, Oldengott J, Stammler A, Bögge H, Glaser T. Reactivities and Electronic Structures of μ-1,2-Peroxo and μ-1,2-Superoxo Co IIICo III Complexes: Electrophilic Reactivity and O 2 Release Induced by Oxidation. Inorg Chem 2023; 62:17913-17930. [PMID: 37838986 DOI: 10.1021/acs.inorgchem.3c02782] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2023]
Abstract
Peroxo complexes are key intermediates in water oxidation catalysis (WOC). Cobalt plays an important role in WOC, either as oxides CoOx or as {CoIII(μ-1,2-peroxo)CoIII} complexes, which are the oldest peroxo complexes known. The oxidation of {CoIII(μ-1,2-peroxo)CoIII} complexes had usually been described to form {CoIII(μ-1,2-superoxo)CoIII} complexes; however, recently the formation of {CoIV(μ-1,2-peroxo)CoIII} species were suggested. Using a bis(tetradentate) dinucleating ligand, we present here the synthesis and characterization of {CoIII(μ-1,2-peroxo)(μ-OH)CoIII} and {CoIII(μ-OH)2CoIII} complexes. Oxidation of {CoIII(μ-1,2-peroxo)(μ-OH)CoIII} at -40 °C in CH3CN provides the stable {CoIII(μ-1,2-superoxo)(μ-OH)CoIII} species and activates electrophilic reactivity. Moreover, {CoIII(μ-1,2-peroxo)(μ-OH)CoIII} catalyzes water oxidation, not molecularly but rather via CoOx films. While {CoIII(μ-1,2-peroxo)(μ-OH)CoIII} can be reversibly deprotonated with DBU at -40 °C in CH3CN, {CoIII(μ-1,2-superoxo)(μ-OH)CoIII} undergoes irreversible conversions upon reaction with bases to a new intermediate that is also the decay product of {CoIII(μ-1,2-superoxo)(μ-OH)CoIII} in aqueous solution at pH > 2. Based on a combination of experimental methods, the new intermediate is proposed to have a {CoII(μ-OH)CoIII} core formed by the release of O2 from {CoIII(μ-1,2-superoxo)(μ-OH)CoIII} confirmed by a 100% yield of O2 upon photocatalytic oxidation of {CoIII(μ-1,2-peroxo)(μ-OH)CoIII}. This release of O2 by oxidation of a peroxo intermediate corresponds to the last step in molecular WOC.
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Affiliation(s)
- Felix Depenbrock
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Thomas Limpke
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, Mülheim an der Ruhr D-45470, Germany
| | - Daniel J SantaLucia
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr D-45470, Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr D-45470, Germany
| | - Stephan Walleck
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Jan Oldengott
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Anja Stammler
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Hartmut Bögge
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Thorsten Glaser
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
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52
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Montgomery CL, Amtawong J, Jordan AM, Kurtz DA, Dempsey JL. Proton transfer kinetics of transition metal hydride complexes and implications for fuel-forming reactions. Chem Soc Rev 2023; 52:7137-7169. [PMID: 37750006 DOI: 10.1039/d3cs00355h] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Proton transfer reactions involving transition metal hydride complexes are prevalent in a number of catalytic fuel-forming reactions, where the proton transfer kinetics to or from the metal center can have significant impacts on the efficiency, selectivity, and stability associated with the catalytic cycle. This review correlates the often slow proton transfer rate constants of transition metal hydride complexes to their electronic and structural descriptors and provides perspective on how to exploit these parameters to control proton transfer kinetics to and from the metal center. A toolbox of techniques for experimental determination of proton transfer rate constants is discussed, and case studies where proton transfer rate constant determination informs fuel-forming reactions are highlighted. Opportunities for extending proton transfer kinetic measurements to additional systems are presented, and the importance of synergizing the thermodynamics and kinetics of proton transfer involving transition metal hydride complexes is emphasized.
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Affiliation(s)
- Charlotte L Montgomery
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
| | - Jaruwan Amtawong
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
| | - Aldo M Jordan
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
| | - Daniel A Kurtz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
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53
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Hashemi A, Khakpour R, Mahdian A, Busch M, Peljo P, Laasonen K. Density functional theory and machine learning for electrochemical square-scheme prediction: an application to quinone-type molecules relevant to redox flow batteries. DIGITAL DISCOVERY 2023; 2:1565-1576. [PMID: 38013904 PMCID: PMC10561546 DOI: 10.1039/d3dd00091e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 09/11/2023] [Indexed: 11/29/2023]
Abstract
Proton-electron transfer (PET) reactions are rather common in chemistry and crucial in energy storage applications. How electrons and protons are involved or which mechanism dominates is strongly molecule and pH dependent. Quantum chemical methods can be used to assess redox potential (Ered.) and acidity constant (pKa) values but the computations are rather time consuming. In this work, supervised machine learning (ML) models are used to predict PET reactions and analyze molecular space. The data for ML have been created by density functional theory (DFT) calculations. Random forest regression models are trained and tested on a dataset that we created. The dataset contains more than 8200 quinone-type organic molecules that each underwent two proton and two electron transfer reactions. Both structural and chemical descriptors are used. The HOMO of the reactant and LUMO of the product participating in the oxidation reaction appeared to be strongly associated with Ered.. Trained models using a SMILES-based structural descriptor can efficiently predict the pKa and Ered. with a mean absolute error of less than 1 and 66 mV, respectively. Good prediction accuracy of R2 > 0.76 and >0.90 was also obtained on the external test set for Ered. and pKa, respectively. This hybrid DFT-ML study can be applied to speed up the screening of quinone-type molecules for energy storage and other applications.
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Affiliation(s)
- Arsalan Hashemi
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
| | - Reza Khakpour
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
| | - Amir Mahdian
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
| | - Michael Busch
- Institute of Theoretical Chemistry, Ulm University Albert-Einstein Allee 11 89069 Ulm Germany
| | - Pekka Peljo
- Research Group of Battery Materials and Technologies, Department of Mechanical and Materials Engineering, Faculty of Technology, University of Turku 20014 Turun Yliopisto Finland
| | - Kari Laasonen
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
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54
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Matsumoto A, Maeda N, Maruoka K. Bidirectional Elongation Strategy Using Ambiphilic Radical Linchpin for Modular Access to 1,4-Dicarbonyls via Sequential Photocatalysis. J Am Chem Soc 2023; 145:20344-20354. [PMID: 37490759 DOI: 10.1021/jacs.3c05337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Organic molecules that can be connected to multiple substrates by sequential C-C bond formations can be utilized as linchpins in multicomponent processes. While they are useful for rapidly increasing molecular complexity, most of the reported linchpin coupling methods rely on the use of organometallic species as strong carbon nucleophiles to form C-C bonds, which narrows the functional group compatibility. Here, we describe a metal-free, radical-mediated coupling approach using a formyl-stabilized phosphonium ylide as a multifunctional linchpin under visible-light photoredox conditions. The present method uses the ambiphilic character of the phosphonium ylide, which serves as both a nucleophilic and an electrophilic carbon-centered radical source. The stepwise and controllable generation of these radical intermediates allows sequential photocatalysis involving two mechanistically distinct radical additions, both of which are initiated by the same photocatalyst in one pot with high functional group tolerance. The methodology enables a bidirectional assembly of the linchpin with two electronically differentiated alkene fragments and thus offers rapid and modular access to 1,4-dicarbonyl compounds as versatile synthetic intermediates.
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Affiliation(s)
- Akira Matsumoto
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Natsumi Maeda
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Keiji Maruoka
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China
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55
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Dumont R, Dowdell J, Song J, Li J, Wang S, Kang W, Li B. Control of charge transport in electronically active systems towards integrated biomolecular circuits (IbC). J Mater Chem B 2023; 11:8302-8314. [PMID: 37464922 DOI: 10.1039/d3tb00701d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
The miniaturization of traditional silicon-based electronics will soon reach its limitation as quantum tunneling and heat become serious problems at the several-nanometer scale. Crafting integrated circuits via self-assembly of electronically active molecules using a "bottom-up" paradigm provides a potential solution to these technological challenges. In particular, integrated biomolecular circuits (IbC) offer promising advantages to achieve this goal, as nature offers countless examples of functionalities entailed by self-assembly and examples of controlling charge transport at the molecular level within the self-assembled structures. To this end, the review summarizes the progress in understanding how charge transport is regulated in biosystems and the key redox-active amino acids that enable the charge transport. In addition, charge transport mechanisms at different length scales are also reviewed, offering key insights for controlling charge transport in IbC in the future.
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Affiliation(s)
- Ryan Dumont
- Department of Mechanical Engineering, Kennesaw State University, Marietta, GA, USA.
| | - Juwaan Dowdell
- Department of Mechanical Engineering, Kennesaw State University, Marietta, GA, USA.
| | - Jisoo Song
- Department of Mechanical Engineering, Kennesaw State University, Marietta, GA, USA.
| | - Jiani Li
- State Key Laboratory of Fine Chemicals, Frontiers Science Centre for Smart Materials Oriented Chemical Engineering, School of Bioengineering, Dalian University of Technology, Dalian, China.
| | - Suwan Wang
- State Key Laboratory of Fine Chemicals, Frontiers Science Centre for Smart Materials Oriented Chemical Engineering, School of Bioengineering, Dalian University of Technology, Dalian, China.
| | - Wei Kang
- State Key Laboratory of Fine Chemicals, Frontiers Science Centre for Smart Materials Oriented Chemical Engineering, School of Bioengineering, Dalian University of Technology, Dalian, China.
- Ningbo Institute of Dalian University of Technology, Ningbo, China
| | - Bo Li
- Department of Mechanical Engineering, Kennesaw State University, Marietta, GA, USA.
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56
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Abstract
In attempts to simulate the protonation of proteins, a major challenge is that the number of protonation states grows rapidly as a function (2N) of the number of protonation sites (N). Expression on the free energy of the protonation state as an N-site Ising model ─ using an empirical Generalized-Born model ─ allows a quantum computer to efficiently determine the important states at a given pH value and subsequently reconstruct the pH titration process at all sites. Compared with the exact results painstakingly obtained with classical computers, the results obtained using quantum computers show good agreement for staphylococcal nuclease and excellent agreement for α-lactalbumin. This work illustrates the effectiveness of quantum computers in sampling important physical states, which may be useful in attacking challenging biomolecular problems.
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Affiliation(s)
- Hao Hu
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
- Polaris Quantum Biotech Inc., Suite 205, 201 W Main St., Durham, North Carolina 27701, United States
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57
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Abstract
Endogenous photosensitizers play a critical role in both beneficial and harmful light-induced transformations in biological systems. Understanding their mode of action is essential for advancing fields such as photomedicine, photoredox catalysis, environmental science, and the development of sun care products. This review offers a comprehensive analysis of endogenous photosensitizers in human skin, investigating the connections between their electronic excitation and the subsequent activation or damage of organic biomolecules. We gather the physicochemical and photochemical properties of key endogenous photosensitizers and examine the relationships between their chemical reactivity, location within the skin, and the primary biochemical events following solar radiation exposure, along with their influence on skin physiology and pathology. An important take-home message of this review is that photosensitization allows visible light and UV-A radiation to have large effects on skin. The analysis presented here unveils potential causes for the continuous increase in global skin cancer cases and emphasizes the limitations of current sun protection approaches.
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Affiliation(s)
- Erick L Bastos
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
| | - Frank H Quina
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
- Department of Chemical Engineering, Polytechnic School, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
| | - Maurício S Baptista
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, 05508-000 São Paulo, São Paulo, Brazil
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58
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Radtke V, Priester D, Heering A, Müller C, Koslowski T, Leito I, Krossing I. The Unified Redox Scale for All Solvents: Consistency and Gibbs Transfer Energies of Electrolytes from their Constituent Single Ions. Chemistry 2023; 29:e202300609. [PMID: 37191477 DOI: 10.1002/chem.202300609] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/28/2023] [Accepted: 05/11/2023] [Indexed: 05/17/2023]
Abstract
We have devised the unified redox scale Eabs H2O , which is valid for all solvents. The necessary single ion Gibbs transfer energy between two different solvents, which only can be determined with extra-thermodynamic assumptions so far, must clearly satisfy two essential conditions: First, the sum of the independent cation and anion values must give the Gibbs transfer energy of the salt they form. The latter is an observable and measurable without extra-thermodynamic assumptions. Second, the values must be consistent for different solvent combinations. With this work, potentiometric measurements on silver ions and on chloride ions show that both conditions are fulfilled using a salt bridge filled with the ionic liquid [N2225 ][NTf2 ]: if compared to the values resulting from known pKL values, the silver and chloride single ion magnitudes combine within a uncertainty of 1.5 kJ mol-1 to the directly measurable transfer magnitudes of the salt AgCl from water to the solvents acetonitrile, propylene carbonate, dimethylformamide, ethanol, and methanol. The resulting values are used to further develop the consistent unified redox potential scale Eabs H2O that now allows to assess and compare redox potentials in and over six different solvents. We elaborate on its implications.
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Affiliation(s)
- Valentin Radtke
- Institut für Anorganische und, Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Denis Priester
- Institut für Anorganische und, Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Agnes Heering
- Institute of Chemistry, University of Tartu, Ravila 14a Str, 50411, Tartu, Estonia
| | - Carina Müller
- Institut für Anorganische und, Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Thorsten Koslowski
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Ivo Leito
- Institute of Chemistry, University of Tartu, Ravila 14a Str, 50411, Tartu, Estonia
| | - Ingo Krossing
- Institut für Anorganische und, Analytische Chemie and Freiburger Materialforschungszentrum (FMF), Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
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59
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Moore SM, Sun C, Steele JL, Laaker EM, Rheingold AL, Doerrer LH. HAA by the first {Mn(iii)OH} complex with all O-donor ligands. Chem Sci 2023; 14:8187-8195. [PMID: 37538819 PMCID: PMC10395311 DOI: 10.1039/d3sc01971c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 07/05/2023] [Indexed: 08/05/2023] Open
Abstract
There is considerable interest in MnOHx moieties, particularly in the stepwise changes in those O-H bonds in tandem with Mn oxidation state changes. The reactivity of aquo-derived ligands, {MOHx}, is also heavily influenced by the electronic character of the other ligands. Despite the prevalence of oxygen coordination in biological systems, preparation of mononuclear Mn complexes of this type with all O-donors is rare. Herein, we report several Mn complexes with perfluoropinacolate (pinF)2- including the first example of a crystallographically characterized mononuclear {Mn(iii)OH} with all O-donors, K2[Mn(OH)(pinF)2], 3. Complex 3 is prepared via deprotonation of K[Mn(OH2)(pinF)2], 1, the pKa of which is estimated to be 18.3 ± 0.3. Cyclic voltammetry reveals quasi-reversible redox behavior for both 1 and 3 with an unusually large ΔEp, assigned to the Mn(iii/ii) couple. Using the Bordwell method, the bond dissociation free energy (BDFE) of the O-H bond in {Mn(ii)-OH2} is estimated to be 67-70 kcal mol-1. Complex 3 abstracts H-atoms from 1,2-diphenylhydrazine, 2,4,6-TTBP, and TEMPOH, the latter of which supports a PCET mechanism. Under basic conditions in air, the synthesis of 1 results in K2[Mn(OAc)(pinF)2], 2, proposed to result from the oxidation of Et2O to EtOAc by a reactive Mn species, followed by ester hydrolysis. Complex 3 alone does not react with Et2O, but addition of O2 at low temperature effects the formation of a new chromophore proposed to be a Mn(iv) species. The related complexes K(18C6)[Mn(iii)(pinF)2], 4, and (Me4N)2[Mn(ii)(pinF)2], 5, have also been prepared and their properties discussed in relation to complexes 1-3.
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Affiliation(s)
- Shawn M Moore
- Boston University, Chemistry Department 590 Commonwealth Avenue Boston Massachusetts 02215 USA
| | - Chen Sun
- Boston University, Chemistry Department 590 Commonwealth Avenue Boston Massachusetts 02215 USA
| | - Jennifer L Steele
- Boston University, Chemistry Department 590 Commonwealth Avenue Boston Massachusetts 02215 USA
| | - Ellen M Laaker
- Boston University, Chemistry Department 590 Commonwealth Avenue Boston Massachusetts 02215 USA
| | - Arnold L Rheingold
- University of California, San Diego Department of Chemistry and Biochemistry 9500 Gilman Drive La Jolla California 92093 USA
| | - Linda H Doerrer
- Boston University, Chemistry Department 590 Commonwealth Avenue Boston Massachusetts 02215 USA
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60
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Cheng L, Li D, Mai BK, Bo Z, Cheng L, Liu P, Yang Y. Stereoselective amino acid synthesis by synergistic photoredox-pyridoxal radical biocatalysis. Science 2023; 381:444-451. [PMID: 37499030 PMCID: PMC10444520 DOI: 10.1126/science.adg2420] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 06/20/2023] [Indexed: 07/29/2023]
Abstract
Developing synthetically useful enzymatic reactions that are not known in biochemistry and organic chemistry is an important challenge in biocatalysis. Through the synergistic merger of photoredox catalysis and pyridoxal 5'-phosphate (PLP) biocatalysis, we developed a pyridoxal radical biocatalysis approach to prepare valuable noncanonical amino acids, including those bearing a stereochemical dyad or triad, without the need for protecting groups. Using engineered PLP enzymes, either enantiomeric product could be produced in a biocatalyst-controlled fashion. Synergistic photoredox-pyridoxal radical biocatalysis represents a powerful platform with which to discover previously unknown catalytic reactions and to tame radical intermediates for asymmetric catalysis.
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Affiliation(s)
- Lei Cheng
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Dian Li
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Binh Khanh Mai
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Zhiyu Bo
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Lida Cheng
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Yang Yang
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
- Biomolecular Science and Engineering (BMSE) Program, University of California Santa Barbara, Santa Barbara, California 93106, USA
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61
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Koone JC, Simmang M, Saenger DL, Hunsicker-Wang LM, Shaw BF. Charge Regulation in a Rieske Proton Pump Pinpoints Zero, One, and Two Proton-Coupled Electron Transfer. J Am Chem Soc 2023. [PMID: 37486967 PMCID: PMC10402712 DOI: 10.1021/jacs.3c03006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
The degree to which redox-driven proton pumps regulate net charge during electron transfer (ΔZET) remains undetermined due to difficulties in measuring the net charge of solvated proteins. Values of ΔZET can reflect reorganization energies or redox potentials associated with ET and can be used to distinguish ET from proton(s)-coupled electron transfer (PCET). Here, we synthesized protein "charge ladders" of a Rieske [2Fe-2S] subunit from Thermus thermophilus (truncTtRp) and made 120 electrostatic measurements of ΔZET across pH. Across pH 5-10, truncTtRp is suspected of transitioning from ET to PCET, and then to two proton-coupled ET (2PCET). Upon reduction, we found that truncTtRp became more negative at pH 6.0 by one unit (ΔZET = -1.01 ± 0.14), consistent with single ET; was isoelectric at pH 8.8 (ΔZET = -0.01 ± 0.45), consistent with PCET; and became more positive at pH 10.6 (ΔZET = +1.37 ± 0.60), consistent with 2PCET. These ΔZET values are attributed to protonation of H154 and H134. Across pH, redox potentials of TtRp (measured previously) correlated with protonation energies of H154 and H134 and ΔZET for truncTtRp, supporting a discrete proton pumping mechanism for Rieske proteins at the Fe-coordinating histidines.
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Affiliation(s)
- Jordan C Koone
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76706, United States
| | - Mikaela Simmang
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Devin L Saenger
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | | | - Bryan F Shaw
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76706, United States
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62
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Peters JC. Advancing electrocatalytic nitrogen fixation: insights from molecular systems. Faraday Discuss 2023; 243:450-472. [PMID: 37021388 PMCID: PMC10524484 DOI: 10.1039/d3fd00017f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
Abstract
Nitrogen fixation has a rich history within the inorganic chemistry community. In recent years attention has (re)focused on developing electrocatalytic systems capable of mediating the nitrogen reduction reaction (N2RR). Well-defined molecular catalyst systems have much to offer in this context. This personal perspective summarizes recent progress from our laboratory at Caltech, pulling together lessons learned from a number of studies we have conducted, placing them within the broader context of thermodynamic efficiency and selectivity for the N2RR. In particular, proton-coupled electron transfer (PCET) provides an attractive strategy to achieve enhanced efficiency for the multi-electron/proton reduction of N2 to produce NH3 (or NH4+), and electrocatalytic PCET (ePCET) via an ePCET mediator affords a promising means of mitigating HER such that the N2RR can be achieved in a catalytic fashion.
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Affiliation(s)
- Jonas C Peters
- California Institute of Technology, Pasadena, CA 91125, USA.
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63
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Groff BD, Cattaneo M, Coste SC, Pressley CA, Mercado BQ, Mayer JM. Independent Tuning of the p Ka or the E1/2 in a Family of Ruthenium Pyridine-Imidazole Complexes. Inorg Chem 2023; 62:10031-10038. [PMID: 37326619 PMCID: PMC10734561 DOI: 10.1021/acs.inorgchem.3c01241] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Two series of RuII(acac)2(py-imH) complexes have been prepared, one with changes to the acac ligands and the other with substitutions to the imidazole. The proton-coupled electron transfer (PCET) thermochemistry of the complexes has been studied in acetonitrile, revealing that the acac substitutions almost exclusively affect the redox potentials of the complex (|ΔE1/2| ≫ |ΔpKa|·0.059 V) while the changes to the imidazole primarily affect its acidity (|ΔpKa|·0.059 V ≫ |ΔE1/2|). This decoupling is supported by DFT calculations, which show that the acac substitutions primarily affect the Ru-centered t2g orbitals, while changes to the py-imH ligand primarily affect the ligand-centered π orbitals. More broadly, the decoupling stems from the physical separation of the electron and proton within the complex and highlights a clear design strategy to separately tune the redox and acid/base properties of H atom donor/acceptor molecules.
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Affiliation(s)
- Benjamin D Groff
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Mauricio Cattaneo
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Scott C Coste
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Chloe A Pressley
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Brandon Q Mercado
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - James M Mayer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
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64
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Zhang J, Mück-Lichtenfeld C, Studer A. Photocatalytic phosphine-mediated water activation for radical hydrogenation. Nature 2023; 619:506-513. [PMID: 37380779 PMCID: PMC10356606 DOI: 10.1038/s41586-023-06141-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 04/27/2023] [Indexed: 06/30/2023]
Abstract
The chemical activation of water would allow this earth-abundant resource to be transferred into value-added compounds, and is a topic of keen interest in energy research1,2. Here, we demonstrate water activation with a photocatalytic phosphine-mediated radical process under mild conditions. This reaction generates a metal-free PR3-H2O radical cation intermediate, in which both hydrogen atoms are used in the subsequent chemical transformation through sequential heterolytic (H+) and homolytic (H•) cleavage of the two O-H bonds. The PR3-OH radical intermediate provides an ideal platform that mimics the reactivity of a 'free' hydrogen atom, and which can be directly transferred to closed-shell π systems, such as activated alkenes, unactivated alkenes, naphthalenes and quinoline derivatives. The resulting H adduct C radicals are eventually reduced by a thiol co-catalyst, leading to overall transfer hydrogenation of the π system, with the two H atoms of water ending up in the product. The thermodynamic driving force is the strong P=O bond formed in the phosphine oxide by-product. Experimental mechanistic studies and density functional theory calculations support the hydrogen atom transfer of the PR3-OH intermediate as a key step in the radical hydrogenation process.
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Affiliation(s)
- Jingjing Zhang
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Münster, Germany
| | - Christian Mück-Lichtenfeld
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Münster, Germany
- Center for Multiscale Theory and Computation, Westfälische Wilhelms-Universität, Münster, Germany
| | - Armido Studer
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Münster, Germany.
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65
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Dey A, Ghorai N, Das A, Ghosh HN. Effects of hydrogen bonding on intramolecular/intermolecular proton-coupled electron transfer using a Ruthenium-anthraquinone dyad in ultrafast time domain. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2023.114709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
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66
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Boyd EA, Peters JC. Highly Selective Fe-Catalyzed Nitrogen Fixation to Hydrazine Enabled by Sm(II) Reagents with Tailored Redox Potential and p Ka. J Am Chem Soc 2023. [PMID: 37376713 DOI: 10.1021/jacs.3c03352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Controlling product selectivity in multiproton, multielectron reductions of unsaturated small molecules is of fundamental interest in catalysis. For the N2 reduction reaction (N2RR) in particular, parameters that dictate selectivity for either the 6H+/6e- product ammonia (NH3) or the 4H+/4e- product hydrazine (N2H4) are poorly understood. To probe this issue, we have developed conditions to invert the selectivity of a tris(phosphino)borane iron catalyst (Fe), with which NH3 is typically the major product of N2R, to instead favor N2H4 as the sole observed fixed-N product (>99:1). This dramatic shift is achieved by replacing moderate reductants and strong acids with a very strongly reducing but weakly acidic SmII-(2-pyrrolidone) core supported by a hexadentate dianionic macrocyclic ligand (SmII-PH) as the net hydrogen-atom donor. The activity and efficiency of the catalyst with this reagent remain high (up to 69 equiv of N2H4 per Fe and 67% fixed-N yield per H+). However, by generating N2H4 as the kinetic product, the overpotential of this Sm-driven reaction is 700 mV lower than that of the mildest reported set of NH3-selective conditions with Fe. Mechanistic data support assignment of iron hydrazido(2-) species FeNNH2 as selectivity-determining: we infer that protonation of FeNNH2 at Nβ, favored by strong acids, releases NH3, whereas one-electron reduction to FeNNH2-, favored by strong reductants such as SmII-PH, produces N2H4 via reactivity initiated at Nα. Spectroscopic data also implicate a role for SmIII-binding to anionic FeN2- (via an Fe-N2- -SmIII species) with respect to catalytic efficacy.
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Affiliation(s)
- Emily A Boyd
- Division of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), Pasadena, California 91125, United States
| | - Jonas C Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), Pasadena, California 91125, United States
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67
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VanderWeide A, Prokopchuk DE. Cyclopentadienyl ring activation in organometallic chemistry and catalysis. Nat Rev Chem 2023:10.1038/s41570-023-00501-1. [PMID: 37258685 DOI: 10.1038/s41570-023-00501-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2023] [Indexed: 06/02/2023]
Abstract
The cyclopentadienyl (Cp) ligand is a cornerstone of modern organometallic chemistry. Since the discovery of ferrocene, the Cp ligand and its various derivatives have become foundational motifs in catalysis, medicine and materials science. Although largely considered an ancillary ligand for altering the stereoelectronic properties of transition metal centres, there is mounting evidence that the core Cp ring structure also serves as a reservoir for reactive protons (H+), hydrides (H-) or radical hydrogen (H•) atoms. This Review chronicles the field of Cp ring activation, highlighting the pivotal role that Cp ligands can have in electrocatalytic H2 production, N2 reduction, hydride transfer reactions and proton-coupled electron transfer.
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68
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Mo X, Deng Y, Lai SKM, Gao X, Yu HL, Low KH, Guo Z, Wu HL, Au-Yeung HY, Tse ECM. Mechanical Interlocking Enhances the Electrocatalytic Oxygen Reduction Activity and Selectivity of Molecular Copper Complexes. J Am Chem Soc 2023; 145:6087-6099. [PMID: 36853653 DOI: 10.1021/jacs.2c10988] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Efficient O2 reduction reaction (ORR) for selective H2O generation enables advanced fuel cell technology. Nonprecious metal catalysts are viable and attractive alternatives to state-of-the-art Pt-based materials that are expensive. Cu complexes inspired by Cu-containing O2 reduction enzymes in nature are yet to reach their desired ORR catalytic performance. Here, the concept of mechanical interlocking is introduced to the ligand architecture to enforce dynamic spatial restriction on the Cu coordination site. Interlocked catenane ligands could govern O2 binding mode, promote electron transfer, and facilitate product elimination. Our results show that ligand interlocking as a catenane steers the ORR selectivity to H2O as the major product via the 4e- pathway, rivaling the selectivity of Pt, and boosts the onset potential by 130 mV, the mass activity by 1.8 times, and the turnover frequency by 1.5 fold as compared to the noninterlocked counterpart. Our Cu catenane complex represents one of the first examples to take advantage of mechanical interlocking to afford electrocatalysts with enhanced activity and selectivity. The mechanistic insights gained through this integrated experimental and theoretical study are envisioned to be valuable not just to the area of ORR energy catalysis but also with broad implications on interlocked metal complexes that are of critical importance to the general fields in redox reactions involving proton-coupled electron transfer steps.
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Affiliation(s)
- Xiaoyong Mo
- Department of Chemistry, HKU-CAS Joint Laboratory of New Materials, University of Hong Kong, Hong Kong, China
| | - Yulin Deng
- Department of Chemistry, HKU-CAS Joint Laboratory of New Materials, University of Hong Kong, Hong Kong, China
| | - Samuel Kin-Man Lai
- Department of Chemistry, HKU-CAS Joint Laboratory of New Materials, University of Hong Kong, Hong Kong, China
| | - Xutao Gao
- Department of Chemistry, HKU-CAS Joint Laboratory of New Materials, University of Hong Kong, Hong Kong, China
| | - Hung-Ling Yu
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
- Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 10617, Taiwan
| | - Kam-Hung Low
- Department of Chemistry, HKU-CAS Joint Laboratory of New Materials, University of Hong Kong, Hong Kong, China
| | - Zhengxiao Guo
- Department of Chemistry, HKU-CAS Joint Laboratory of New Materials, University of Hong Kong, Hong Kong, China
- HKU Zhejiang Institute of Research and Innovation, Hangzhou 311305, People's Republic of China
| | - Heng-Liang Wu
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
- Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 10617, Taiwan
| | - Ho Yu Au-Yeung
- Department of Chemistry, HKU-CAS Joint Laboratory of New Materials, University of Hong Kong, Hong Kong, China
- State Key Laboratory of Synthetic Chemistry, University of Hong Kong, Hong Kong, China
| | - Edmund C M Tse
- Department of Chemistry, HKU-CAS Joint Laboratory of New Materials, University of Hong Kong, Hong Kong, China
- HKU Zhejiang Institute of Research and Innovation, Hangzhou 311305, People's Republic of China
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69
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Mayer JM. Bonds over Electrons: Proton Coupled Electron Transfer at Solid-Solution Interfaces. J Am Chem Soc 2023; 145:7050-7064. [PMID: 36943755 PMCID: PMC10080693 DOI: 10.1021/jacs.2c10212] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
This Perspective argues that most redox reactions of materials at an interface with a protic solution involve net proton-coupled electron transfer (PCET) (or other cation-coupled ET). This view contrasts with the traditional electron-transfer-focused view of redox reactions at semiconductors, but redox processes at metal surfaces are often described as PCET. Taking a thermodynamic perspective, transfer of an electron is typically accompanied by a stoichiometric proton, much as the chemistry of lithium-ion batteries involves coupled transfers of e- and Li+. The PCET viewpoint implicates the surface-H bond dissociation free energy (BDFE) as the preeminent energetic parameter and its conceptual equivalents, the electrochemical ne-/nH+ potential versus the reversible hydrogen electrode (RHE) and the free energy of hydrogenation, ΔG°H. These parameters capture the thermochemistry of PCET at interfaces better than electronic parameters such as Fermi energies, electron chemical potentials, flat-band potentials, or band-edge energies. A unified picture of PCET at metal and semiconductor surfaces is presented. Exceptions, limitations, implications, and future directions motivated by this approach are described.
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Affiliation(s)
- James M Mayer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
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70
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Zhao N, Goetz MK, Schneider JE, Anderson JS. Testing the Limits of Imbalanced CPET Reactivity: Mechanistic Crossover in H-Atom Abstraction by Co(III)-Oxo Complexes. J Am Chem Soc 2023; 145:5664-5673. [PMID: 36867838 PMCID: PMC10023487 DOI: 10.1021/jacs.2c10553] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Transition metal-oxo complexes are key intermediates in a variety of oxidative transformations, notably C-H bond activation. The relative rate of C-H bond activation mediated by transition metal-oxo complexes is typically predicated on substrate bond dissociation free energy in cases with a concerted proton-electron transfer (CPET). However, recent work has demonstrated that alternative stepwise thermodynamic contributions such as acidity/basicity or redox potentials of the substrate/metal-oxo may dominate in some cases. In this context, we have found basicity-governed concerted activation of C-H bonds with the terminal CoIII-oxo complex PhB(tBuIm)3CoIIIO. We have been interested in testing the limits of such basicity-dependent reactivity and have synthesized an analogous, more basic complex, PhB(AdIm)3CoIIIO, and studied its reactivity with H-atom donors. This complex displays a higher degree of imbalanced CPET reactivity than PhB(tBuIm)3CoIIIO with C-H substrates, and O-H activation of phenol substrates displays mechanistic crossover to stepwise proton transfer-electron transfer (PTET) reactivity. Analysis of the thermodynamics of proton transfer (PT) and electron transfer (ET) reveals a distinct thermodynamic crossing point between concerted and stepwise reactivity. Furthermore, the relative rates of stepwise and concerted reactivity suggest that maximally imbalanced systems provide the fastest CPET rates up to the point of mechanistic crossover, which results in slower product formation.
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Affiliation(s)
- Norman Zhao
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | | | - Joseph E. Schneider
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | - John S. Anderson
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
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71
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Yang Y, Volpato GA, Rossin E, Peruffo N, Tumbarello F, Nicoletti C, Bonetto R, Paoloni L, Umari P, Colusso E, Dell'Amico L, Berardi S, Collini E, Caramori S, Agnoli S, Sartorel A. Photoelectrochemical C-H Activation Through a Quinacridone Dye Enabling Proton-Coupled Electron Transfer. CHEMSUSCHEM 2023; 16:e202201980. [PMID: 36507568 DOI: 10.1002/cssc.202201980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/30/2022] [Indexed: 06/17/2023]
Abstract
Dye-sensitized photoanodes for C-H activation in organic substrates are assembled by vacuum sublimation of a commercially available quinacridone (QNC) dye in the form of nanosized rods onto fluorine-doped tin oxide (FTO), TiO2 , and SnO2 slides. The photoanodes display extended absorption in the visible range (450-600 nm) and ultrafast photoinduced electron injection (<1 ps, as revealed by transient absorption spectroscopy) of the QNC dye into the semiconductor. The proton-coupled electron-transfer reactivity of QNC is exploited for generating a nitrogen-based radical as its oxidized form, which is competent in C-H bond activation. The key reactivity parameter is the bond-dissociation free energy (BDFE) associated with the N⋅/N-H couple in QNC of 80.5±2.3 kcal mol-1 , which enables hydrogen atom abstraction from allylic or benzylic C-H moieties. A photoelectrochemical response is indeed observed for organic substrates characterized by C-H bonds with BDFE below the 80.5 kcal mol-1 threshold, such as γ-terpinene, xanthene, or dihydroanthracene. This work provides a rational, mechanistically oriented route to the design of dye-sensitized photoelectrodes for selective organic transformations.
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Affiliation(s)
- Yunshuo Yang
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Giulia Alice Volpato
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Elena Rossin
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Nicola Peruffo
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Francesco Tumbarello
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Catia Nicoletti
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Ruggero Bonetto
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Lorenzo Paoloni
- Department of Physics and Astronomy, University of Padova, via F. Marzolo 8, 35131, Padova, Italy
| | - Paolo Umari
- Department of Physics and Astronomy, University of Padova, via F. Marzolo 8, 35131, Padova, Italy
| | - Elena Colusso
- Department of Industrial Engineering and INSTM, University of Padova, F. Marzolo 9, 35131, Padova, Italy
| | - Luca Dell'Amico
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Serena Berardi
- Department of Chemical and Pharmaceutical Sciences, Centro Interuniversitario per la Conversione Chimica dell'Energia Solare (SolarChem), Sez. di Ferrara, University of Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy
| | - Elisabetta Collini
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Stefano Caramori
- Department of Chemical and Pharmaceutical Sciences, Centro Interuniversitario per la Conversione Chimica dell'Energia Solare (SolarChem), Sez. di Ferrara, University of Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy
| | - Stefano Agnoli
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
| | - Andrea Sartorel
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131, Padova, Italy
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72
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Renzi P, Azzi E, Ascensio S, Parisotto S, Sordello F, Pellegrino F, Ghigo G, Deagostino A. Inexpensive and bench stable diarylmethylium tetrafluoroborates as organocatalysts in the light mediated hydrosulfonylation of unactivated alkenes. Chem Sci 2023; 14:2721-2734. [PMID: 36908942 PMCID: PMC9993860 DOI: 10.1039/d3sc00182b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 02/10/2023] [Indexed: 02/12/2023] Open
Abstract
In this paper, we present the synthetic potential of diarylmethylium tetrafluoroborates as catalysts for the visible light promoted hydrosulfonylation of unactivated alkenes. For the first time, these salts, which are bench stable and easily preparable on a multi-gram scale, were employed as organocatalysts. Interestingly, a catalyst loading of only 1 mol% allowed sulfone products to be efficiently obtained from good-to-excellent yields with high functional-group tolerance and scalability up to 15 mmol of alkene. The mechanistic study, both experimental and computational, presented here, revealed an alternative mechanism for the formation of the key sulfonyl radical. Indeed, the photoactive species was proved not to be the diarylcarbenium salt itself, but two intermediates, a stable S-C adduct and an ion couple, that were formed after its interaction with sodium benzenesulfinate. Upon absorbing light, the ion couple could reach an excited state with a charge-transfer character which gave the fundamental sulfonyl radical. A PCET (proton-coupled electron transfer) closes the catalytic cycle reforming the diarylcarbenium salt.
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Affiliation(s)
- Polyssena Renzi
- Department of Chemistry, University of Torino Via Pietro Giuria, 7 10125 Torino Italy
| | - Emanuele Azzi
- Department of Chemistry, University of Torino Via Pietro Giuria, 7 10125 Torino Italy
| | - Sylvain Ascensio
- Department of Chemistry, University of Torino Via Pietro Giuria, 7 10125 Torino Italy
| | - Stefano Parisotto
- Department of Chemistry, University of Torino Via Pietro Giuria, 7 10125 Torino Italy
| | - Fabrizio Sordello
- Department of Chemistry, University of Torino Via Pietro Giuria, 7 10125 Torino Italy
| | - Francesco Pellegrino
- Department of Chemistry, University of Torino Via Pietro Giuria, 7 10125 Torino Italy
| | - Giovanni Ghigo
- Department of Chemistry, University of Torino Via Pietro Giuria, 7 10125 Torino Italy
| | - Annamaria Deagostino
- Department of Chemistry, University of Torino Via Pietro Giuria, 7 10125 Torino Italy
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73
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Sonea A, Branch KL, Warren JJ. The Pattern of Hydroxyphenyl-Substitution Influences CO 2 Reduction More Strongly than the Number of Hydroxyphenyl Groups in Iron-Porphyrin Electrocatalysts. ACS Catal 2023. [DOI: 10.1021/acscatal.2c06275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Affiliation(s)
- Ana Sonea
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Kaitlin L. Branch
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Jeffrey J. Warren
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
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74
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Chen J, Zhang W, Wang L, Yu G. Recent Research Progress of Organic Small-Molecule Semiconductors with High Electron Mobilities. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2210772. [PMID: 36519670 DOI: 10.1002/adma.202210772] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 12/13/2022] [Indexed: 06/17/2023]
Abstract
Organic electronics has made great progress in the past decades, which is inseparable from the innovative development of organic electronic devices and the diversity of organic semiconductor materials. It is worth mentioning that both of these great advances are inextricably linked to the development of organic high-performance semiconductor materials, especially the representative n-type organic small-molecule semiconductor materials with high electron mobilities. The n-type organic small molecules have the advantages of simple synthesis process, strong intermolecular stacking, tunable molecular structure, and easy to functionalize structures. Furthermore, the n-type semiconductor is a remarkable and important component for constructing complementary logic circuits and p-n heterojunction structures. Therefore, n-type organic semiconductors play an extremely important role in the field of organic electronic materials and are the basis for the industrialization of organic electronic functional devices. This review focuses on the modification strategies of organic small molecules with high electron mobility at molecular level, and discusses in detail the applications of n-type small-molecule semiconductor materials with high mobility in organic field-effect transistors, organic light-emitting transistors, organic photodetectors, and gas sensors.
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Affiliation(s)
- Jiadi Chen
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Weifeng Zhang
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Liping Wang
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Gui Yu
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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75
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Franceschi P, Rossin E, Goti G, Scopano A, Vega-Peñaloza A, Natali M, Singh D, Sartorel A, Dell'Amico L. A Proton-Coupled Electron Transfer Strategy to the Redox-Neutral Photocatalytic CO 2 Fixation. J Org Chem 2023; 88:6454-6464. [PMID: 36760023 DOI: 10.1021/acs.joc.2c02952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Herein, we report our study on the design and development of a novel photocarboxylation method. We have used an organic photoredox catalyst (PC, 4CzIPN) and differently substituted dihydropyridines (DHPs) in combination with an organic base (1,5,7-triazabicyclodec-5-ene, TBD) to access a proton-coupled electron transfer (PCET) based manifold. In depth mechanistic investigations merging experimental analysis (NMR, IR, cyclic voltammetry) and density-functional theory (DFT) calculations reveal the key activity of a H-bonding complex between the DHP and the base. The thermodynamic and kinetic benefits of the PCET mechanism allowed the implementation of a redox-neutral fixation process leading to synthetically relevant carboxylic acids (18 examples with isolated yields up to 75%) under very mild reaction conditions. Finally, diverse product manipulations were performed to demonstrate the synthetic versatility of the obtained products.
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Affiliation(s)
- Pietro Franceschi
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Elena Rossin
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Giulio Goti
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Angelo Scopano
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Alberto Vega-Peñaloza
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Mirco Natali
- Department of Chemical, Pharmaceutical, and Agricultural Sciences, University of Ferrara, Via L. Borsari 46, 44121 Ferrara, Italy
| | - Deepak Singh
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Andrea Sartorel
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Luca Dell'Amico
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
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76
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Prather KV, Tsui EY. Photoinduced Ligand-to-Metal Charge Transfer of Cobaltocene: Radical Release and Catalytic Cyclotrimerization. Inorg Chem 2023; 62:2128-2134. [PMID: 36701811 DOI: 10.1021/acs.inorgchem.2c03779] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Irradiation of cobalt metallocenes at the ligand-to-metal charge transfer energies results in the labilization of the cyclopentadienyl-cobalt bond and radical release. The cyclopentadienyl radical is detected by electron paramagnetic resonance (EPR) spectroscopy using a spin trap and can also be chemically trapped using hydrogen-atom-donating reagents. This reaction presents a new photochemical method of generating new cobalt complexes or of forming cyclopentadienyl cobalt(I) species that are active for catalytic [2 + 2 + 2] cyclotrimerization reactions. More importantly, these results also show that cobaltocene should not be considered as a photostable redox reagent under many conditions, including those relevant to photovoltaics or photocatalysis.
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Affiliation(s)
- Keaton V Prather
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Emily Y Tsui
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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77
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Inverse kinetic isotope effects in the oxygen reduction reaction at platinum single crystals. Nat Chem 2023; 15:271-277. [PMID: 36357789 DOI: 10.1038/s41557-022-01084-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 10/03/2022] [Indexed: 11/12/2022]
Abstract
Although the oxygen reduction reaction (ORR) involves multiple proton-coupled electron transfer processes, early studies reported the absence of kinetic isotope effects (KIEs) on polycrystalline platinum, probably due to the use of unpurified D2O. Here we developed a methodology to prepare ultra-pure D2O, which is indispensable for reliably investigating extremely surface-sensitive platinum single crystals. We find that Pt(111) exhibits much higher ORR activity in D2O than in H2O, with potential-dependent inverse KIEs of ~0.5, whereas Pt(100) and Pt(110) exhibit potential-independent inverse KIEs of ~0.8. Such inverse KIEs are closely correlated to the lower *OD coverage and weakened *OD binding strength relative to *OH, which, based on theoretical calculations, are attributed to the differences in their zero-point energies. This study suggests that the competing adsorption between *OH/*OD and *O2 probably plays an important role in the ORR rate-determining steps that involve a chemical step preceding an electrochemical step (CE mechanism).
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78
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Matsubara Y, Ishitani O. Photochemical formation of hydride using transition metal complexes and its application to photocatalytic reduction of the coenzyme NAD(P)+ and its model compounds. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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79
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Abstract
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 co-electrocatalysis and discuss possible future directions for the field.
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Affiliation(s)
- Amelia G Reid
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States
| | - Charles W Machan
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States
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80
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Bower JK, Reese MS, Mazin IM, Zarnitsa LM, Cypcar AD, Moore CE, Sokolov AY, Zhang S. C(sp 3)-H cyanation by a formal copper(iii) cyanide complex. Chem Sci 2023; 14:1301-1307. [PMID: 36756315 PMCID: PMC9891353 DOI: 10.1039/d2sc06573h] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 01/05/2023] [Indexed: 01/18/2023] Open
Abstract
High-valent metal oxo complexes are prototypical intermediates for the activation and hydroxylation of alkyl C-H bonds. Substituting the oxo ligand with other functional groups offers the opportunity for additional C-H functionalization beyond C-O bond formation. However, few species aside from metal oxo complexes have been reported to both activate and functionalize alkyl C-H bonds. We herein report the first example of an isolated copper(iii) cyanide complex (LCuIIICN) and its C-H cyanation reactivity. We found that the redox potential (E ox) of substrates, instead of C-H bond dissociation energy, is a key determinant of the rate of PCET, suggesting an oxidative asynchronous CPET or ETPT mechanism. Among substrates with the same BDEs, those with low redox potentials transfer H atoms up to a million-fold faster. Capitalizing on this mechanistic insight, we found that LCuIIICN is highly selective for cyanation of amines, which is predisposed to oxidative asynchronous or stepwise transfer of H+/e-. Our study demonstrates that the asynchronous effect of PCET is an appealing tool for controlling the selectivity of C-H functionalization.
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Affiliation(s)
- Jamey K. Bower
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Maxwell S. Reese
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Ilia M. Mazin
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Lina M. Zarnitsa
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Andrew D. Cypcar
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Curtis E. Moore
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Alexander Yu. Sokolov
- Department of Chemistry and Biochemistry, The Ohio State University100 W. 18 AveColumbusOH43210USA
| | - Shiyu Zhang
- Department of Chemistry and Biochemistry, The Ohio State University 100 W. 18th Ave Columbus OH 43210 USA
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81
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Kang S, Park BY, Moon D, Han MS. High-Throughput Approach for Facile Access to Hetero-Dinuclear Synergistic Metal Complex for H 2O 2 Activation and Its Implications. ACS APPLIED MATERIALS & INTERFACES 2023; 15:4175-4183. [PMID: 36622965 DOI: 10.1021/acsami.2c21955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Hetero-dinuclear synergic catalysis is a promising approach for improving catalytic performance. However, employing it is challenging because the design principles for the metal complex are still not well understood. Further, these complexes have a broader set of possibilities than mononuclear or homometallic systems, increasing the time and effort required to understand them. In this study, we explored a high-throughput approach to obtain a new hetero-dinuclear synergistic metal complex for H2O2 activation. From the 1152 combinations of metal complex candidates obtained by changing three variables (metal ions, unsymmetrical dinucleating ligands, and pH), the lead complex (L3-(Ni, Co)), which has the highest peroxidase activity, was derived using colorimetric parallel analysis. A series of control experiments revealed that L3 plays a crucial role in the formation of active L3-(Ni, Co) complexes, Co2+ acts as a catalytic center, and Ni2+ serves as an assistant catalytic site within L3-(Ni, Co). In addition, the catalytic efficiency of L3-(Ni, Co), which was 125 times that of the homo-bimetallic complex (L3-(Co, Co)), revealed clear hetero-bimetallic synergism in the buffer. The ultraviolet-visible study and electron paramagnetic resonance-based spin-trap experiment provided mechanistic insight into H2O2 activation by the intermediate, which was found to be induced by the reaction of L3-(Ni, Co) and H2O2. Moreover, the intermediate could act as a donor of the hydroperoxyl radical (•OOH) in the buffer. Furthermore, L3-(Ni, Co) demonstrated potential for application as a signal transducer for H2O2 in an enzyme-coupled cascade assay that can be used for the colorimetric detection of glucose.
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Affiliation(s)
- Seungyoon Kang
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Byoung Yong Park
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - Dohyun Moon
- Beamline Department, Pohang Accelerator Laboratory, Pohang 37673, Republic of Korea
| | - Min Su Han
- Department of Chemistry, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
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82
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Abstract
The emergence of modern photocatalysis, characterized by mildness and selectivity, has significantly spurred innovative late-stage C-H functionalization approaches that make use of low energy photons as a controllable energy source. Compared to traditional late-stage functionalization strategies, photocatalysis paves the way toward complementary and/or previously unattainable regio- and chemoselectivities. Merging the compelling benefits of photocatalysis with the late-stage functionalization workflow offers a potentially unmatched arsenal to tackle drug development campaigns and beyond. This Review highlights the photocatalytic late-stage C-H functionalization strategies of small-molecule drugs, agrochemicals, and natural products, classified according to the targeted C-H bond and the newly formed one. Emphasis is devoted to identifying, describing, and comparing the main mechanistic scenarios. The Review draws a critical comparison between established ionic chemistry and photocatalyzed radical-based manifolds. The Review aims to establish the current state-of-the-art and illustrate the key unsolved challenges to be addressed in the future. The authors aim to introduce the general readership to the main approaches toward photocatalytic late-stage C-H functionalization, and specialist practitioners to the critical evaluation of the current methodologies, potential for improvement, and future uncharted directions.
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Affiliation(s)
- Peter Bellotti
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149Münster, Germany
| | - Huan-Ming Huang
- School of Physical Science and Technology, ShanghaiTech University, 201210Shanghai, China
| | - Teresa Faber
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149Münster, Germany
| | - Frank Glorius
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149Münster, Germany
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83
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Tyson K, Tangtartharakul CB, Zeug M, Findling N, Haddy A, Hvastkovs E, Choe JY, Kim JE, Offenbacher AR. Electrochemical and Structural Study of the Buried Tryptophan in Azurin: Effects of Hydration and Polarity on the Redox Potential of W48. J Phys Chem B 2023; 127:133-143. [PMID: 36542812 PMCID: PMC9841983 DOI: 10.1021/acs.jpcb.2c06677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 11/16/2022] [Indexed: 12/24/2022]
Abstract
Tryptophan serves as an important redox-active amino acid in mediating electron transfer and mitigating oxidative damage in proteins. We previously showed a difference in electrochemical potentials for two tryptophan residues in azurin with distinct hydrogen-bonding environments. Here, we test whether reducing the side chain bulk at position Phe110 to Leu, Ser, or Ala impacts the electrochemical potentials (E°) for tryptophan at position 48. X-ray diffraction confirmed the influx of crystallographically resolved water molecules for both the F110A and F110L tyrosine free azurin mutants. The local environments of W48 in all azurin mutants were further evaluated by UV resonance Raman (UVRR) spectroscopy to probe the impact of mutations on hydrogen bonding and polarity. A correlation between the frequency of the ω17 mode─considered a vibrational marker for hydrogen bonding─and E° is proposed. However, the trend is opposite to the expectation from a previous study on small molecules. Density functional theory calculations suggest that the ω17 mode reflects hydrogen bonding as well as local polarity. Further, the UVRR data reveal different intensity/frequency shifts of the ω9/ω10 vibrational modes that characterize the local H-bonding environments of tryptophan. The cumulative data support that the presence of water increases E° and reveal properties of the protein microenvironment surrounding tryptophan.
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Affiliation(s)
- Kristin Tyson
- Department
of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
| | - Chanin B. Tangtartharakul
- Department
of Chemistry and Biochemistry, University
of California at San Diego, La Jolla, California 92093, United States
| | - Matthias Zeug
- Department
of Chemistry, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville North Carolina, 27858, United States
| | - Nathan Findling
- Department
of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
| | - Alice Haddy
- Department
of Chemistry and Biochemistry, University
of North Carolina at Greensboro, Greensboro, North Carolina 27402, United States
| | - Eli Hvastkovs
- Department
of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
| | - Jun-yong Choe
- Department
of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
- Department
of Chemistry, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville North Carolina, 27858, United States
| | - Judy E. Kim
- Department
of Chemistry and Biochemistry, University
of California at San Diego, La Jolla, California 92093, United States
| | - Adam R. Offenbacher
- Department
of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
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84
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Dantignana V, Pérez-Segura MC, Besalú-Sala P, Delgado-Pinar E, Martínez-Camarena Á, Serrano-Plana J, Álvarez-Núñez A, Castillo CE, García-España E, Luis JM, Basallote MG, Costas M, Company A. Characterization of a Ferryl Flip in Electronically Tuned Nonheme Complexes. Consequences in Hydrogen Atom Transfer Reactivity. Angew Chem Int Ed Engl 2023; 62:e202211361. [PMID: 36305539 PMCID: PMC10107328 DOI: 10.1002/anie.202211361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Indexed: 12/04/2022]
Abstract
Two oxoiron(IV) isomers (R 2a and R 2b) of general formula [FeIV (O)(R PyNMe3 )(CH3 CN)]2+ are obtained by reaction of their iron(II) precursor with NBu4 IO4 . The two isomers differ in the position of the oxo ligand, cis and trans to the pyridine donor. The mechanism of isomerization between R 2a and R 2b has been determined by kinetic and computational analyses uncovering an unprecedented path for interconversion of geometrical oxoiron(IV) isomers. The activity of the two oxoiron(IV) isomers in hydrogen atom transfer (HAT) reactions shows that R 2a reacts one order of magnitude faster than R 2b, which is explained by a repulsive noncovalent interaction between the ligand and the substrate in R 2b. Interestingly, the electronic properties of the R substituent in the ligand pyridine ring do not have a significant effect on reaction rates. Overall, the intrinsic structural aspects of each isomer define their relative HAT reactivity, overcoming changes in electronic properties of the ligand.
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Affiliation(s)
- Valeria Dantignana
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - M Carmen Pérez-Segura
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Instituto de Biomoléculas (INBIO), Universidad de Cádiz, Puerto Real, 11510, Cádiz, Spain
| | - Pau Besalú-Sala
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Estefanía Delgado-Pinar
- Departamento de Química Inorgánica, Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático José Beltrán, Paterna, 46980, Valencia 2, Spain
| | - Álvaro Martínez-Camarena
- Departamento de Química Inorgánica, Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático José Beltrán, Paterna, 46980, Valencia 2, Spain
| | - Joan Serrano-Plana
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Andrea Álvarez-Núñez
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Carmen E Castillo
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Instituto de Biomoléculas (INBIO), Universidad de Cádiz, Puerto Real, 11510, Cádiz, Spain
| | - Enrique García-España
- Departamento de Química Inorgánica, Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático José Beltrán, Paterna, 46980, Valencia 2, Spain
| | - Josep M Luis
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Manuel G Basallote
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Instituto de Biomoléculas (INBIO), Universidad de Cádiz, Puerto Real, 11510, Cádiz, Spain
| | - Miquel Costas
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
| | - Anna Company
- Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, C/Mª Aurèlia Capmany 69, 17003, Girona, Catalonia, Spain
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85
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Ohmatsu K, Suzuki R, Fujita H, Ooi T. Zwitterionic Diphenylphosphinyl Amidate as a Powerful Photoinduced Hydrogen-Atom-Transfer Catalyst for C-H Alkylation of Simple Alkanes. J Org Chem 2023; 88:6553-6556. [PMID: 36606526 DOI: 10.1021/acs.joc.2c02362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The chemical and physical properties of amides change substantially when the electron-withdrawing groups attached to the nitrogen are varied. Herein, we report the superior performance of N-diphenylphosphinyl 1,2,3-triazolium amidate as a photoinduced hydrogen-atom transfer catalyst compared to its N-benzoyl analog. A binary catalyst system of the phosphinyl amidate and an Ir-based photocatalyst enables the alkylation of unbiased C-H bonds.
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Affiliation(s)
- Kohsuke Ohmatsu
- Institute of Transformative Bio-Molecules (WPI-ITbM), and Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - Ryuhei Suzuki
- Institute of Transformative Bio-Molecules (WPI-ITbM), and Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - Hiroki Fujita
- Institute of Transformative Bio-Molecules (WPI-ITbM), and Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan
| | - Takashi Ooi
- Institute of Transformative Bio-Molecules (WPI-ITbM), and Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan
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86
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Bortolato T, Simionato G, Vayer M, Rosso C, Paoloni L, Benetti EM, Sartorel A, Lebœuf D, Dell’Amico L. The Rational Design of Reducing Organophotoredox Catalysts Unlocks Proton-Coupled Electron-Transfer and Atom Transfer Radical Polymerization Mechanisms. J Am Chem Soc 2023; 145:1835-1846. [PMID: 36608266 PMCID: PMC9881005 DOI: 10.1021/jacs.2c11364] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Photocatalysis has become a prominent tool in the arsenal of organic chemists to develop and (re)imagine transformations. However, only a handful of versatile organic photocatalysts (PCs) are available, hampering the discovery of new reactivities. Here, we report the design and complete physicochemical characterization of 9-aryl dihydroacridines (9ADA) and 12-aryl dihydrobenzoacridines (12ADBA) as strong reducing organic PCs. Punctual structural variations modulate their molecular orbital distributions and unlock locally or charge-transfer (CT) excited states. The PCs presenting a locally excited state showed better performances in photoredox defunctionalization processes (yields up to 92%), whereas the PCs featuring a CT excited state produced promising results in atom transfer radical polymerization under visible light (up to 1.21 Đ, and 98% I*). Unlike all the PC classes reported so far, 9ADA and 12ADBA feature a free NH group that enables a catalytic multisite proton-coupled electron transfer (MS-PCET) mechanism. This manifold allows the reduction of redox-inert substrates including aryl, alkyl halides, azides, phosphate and ammonium salts (Ered up to -2.83 vs SCE) under single-photon excitation. We anticipate that these new PCs will open new mechanistic manifolds in the field of photocatalysis by allowing access to previously inaccessible radical intermediates under one-photon excitation.
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Affiliation(s)
- Tommaso Bortolato
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Gianluca Simionato
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Marie Vayer
- Institut
de Science et d’Ingénierie Supramoléculaires
(ISIS), CNRS UMR 7006, Université
de Strasbourg, 8 allée Gaspard Monge, 67000Strasbourg, France
| | - Cristian Rosso
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Lorenzo Paoloni
- Dipartimento
di Fisica e Astronomia G. Galilei, University
of Padova, Via Marzolo
8, 35131, Padova, Italy
| | - Edmondo M. Benetti
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Andrea Sartorel
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - David Lebœuf
- Institut
de Science et d’Ingénierie Supramoléculaires
(ISIS), CNRS UMR 7006, Université
de Strasbourg, 8 allée Gaspard Monge, 67000Strasbourg, France,E-mail:
| | - Luca Dell’Amico
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy,E-mail:
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87
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Stephens DN, Szilagyi RK, Roehling PN, Arulsamy N, Mock MT. Catalytic Ammonia Oxidation to Dinitrogen by a Nickel Complex. Angew Chem Int Ed Engl 2023; 62:e202213462. [PMID: 36279321 DOI: 10.1002/anie.202213462] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Indexed: 11/07/2022]
Abstract
We report a nickel complex for catalytic oxidation of ammonia to dinitrogen under ambient conditions. Using the aryloxyl radical 2,4,6-tri-tert-butylphenoxyl (t Bu3 ArO⋅) as a H atom acceptor to cleave the N-H bond of a coordinated NH3 ligand up to 56 equiv of N2 per Ni center can be generated. Employing the N-oxyl radical 2,2,6,6-(tetramethylpiperidin-1-yl)oxyl (TEMPO⋅) as the H-atom acceptor, up to 15 equiv of N2 per Ni center are formed. A bridging Ni-hydrazine product identified by isotopic nitrogen (15 N) studies and supported by computational models indicates the N-N bond forming step occurs by bimetallic homocoupling of two paramagnetic [Ni]-NH2 fragments. Ni-mediated hydrazine disproportionation to N2 and NH3 completes the catalytic cycle.
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Affiliation(s)
- David N Stephens
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
| | - Robert K Szilagyi
- Department of Chemistry, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Paige N Roehling
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
| | - Navamoney Arulsamy
- Department of Chemistry, University of Wyoming, Laramie, Wyoming 82071, USA
| | - Michael T Mock
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
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88
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Kuo DY, Nishiwaki E, Rivera-Maldonado RA, Cossairt BM. The Role of Hydrogen Adsorption Site Diversity in Catalysis on Transition-Metal Phosphide Surfaces. ACS Catal 2022. [DOI: 10.1021/acscatal.2c04936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Ding-Yuan Kuo
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Emily Nishiwaki
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | | | - Brandi M. Cossairt
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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89
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Tran BG, Carta V, Pink M, Caulton KG, Smith JM. Facile Addition of B-H and B-B Bonds to an Iron(IV) Nitride Complex. Inorg Chem 2022; 61:19800-19805. [PMID: 36441910 DOI: 10.1021/acs.inorgchem.2c02931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The nitride ligand in the iron(IV) complex PhB(iPr2Im)3Fe≡N reacts with boron hydrides to afford PhB(iPr2Im)3FeN(B)H (B = 9-BBN (1), Bpin (2)) and with (Bpin)2 to afford PhB(iPr2Im)3FeN(Bpin)2 (3). The iron(II) borylamido products have all been structurally and spectroscopically characterized, demonstrating facile insertion into B-H and B-B bonds by PhB(iPr2Im)3Fe≡N. Density functional theory (DFT) calculations reveal that the quintet state (S = 2) is significantly lower in energy than the singlet (S = 0) and triplet (S = 1) states for all products. Stoichiometric reaction with (Bpin)2 does not produce the mono-borylated iron imido species PhB(iPr2Im)3FeN(Bpin). DFT calculations suggest that this is because PhB(iPr2Im)3FeN(Bpin) is unstable toward disproportionation to the starting iron(IV) nitride and PhB(iPr2Im)3FeN(Bpin)2. Attempts at B-C bond insertion using phenyl- and benzyl-pinacol borane were unsuccessful, which we attribute to unfavorable kinetics.
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Affiliation(s)
- Bao G Tran
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Veronica Carta
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Maren Pink
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Kenneth G Caulton
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Jeremy M Smith
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
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90
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Tanabe Y, Nishibayashi Y. Recent advances in catalytic nitrogen fixation using transition metal–dinitrogen complexes under mild reaction conditions. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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91
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Shin NY, Tsui E, Reinhold A, Scholes GD, Bird MJ, Knowles RR. Radicals as Exceptional Electron-Withdrawing Groups: Nucleophilic Aromatic Substitution of Halophenols Via Homolysis-Enabled Electronic Activation. J Am Chem Soc 2022; 144:21783-21790. [PMID: 36395367 PMCID: PMC10512454 DOI: 10.1021/jacs.2c10296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
While heteroatom-centered radicals are understood to be highly electrophilic, their ability to serve as transient electron-withdrawing groups and facilitate polar reactions at distal sites has not been extensively developed. Here, we report a new strategy for the electronic activation of halophenols, wherein generation of a phenoxyl radical via formal homolysis of the aryl O-H bond enables direct nucleophilic aromatic substitution of the halide with carboxylate nucleophiles under mild conditions. Pulse radiolysis and transient absorption studies reveal that the neutral oxygen radical (O•) is indeed an extraordinarily strong electron-withdrawing group [σp-(O•) = 2.79 vs σp-(NO2) = 1.27]. Additional mechanistic and computational studies indicate that the key phenoxyl intermediate serves as an open-shell electron-withdrawing group in these reactions, lowering the barrier for nucleophilic substitution by more than 20 kcal/mol relative to the closed-shell phenol form of the substrate. By using radicals as transient activating groups, this homolysis-enabled electronic activation strategy provides a powerful platform to expand the scope of nucleophile-electrophile couplings and enable previously challenging transformations.
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Affiliation(s)
- Nick Y. Shin
- Department of Chemistry, Princeton University, Princeton NJ 08544 (USA)
| | - Elaine Tsui
- Department of Chemistry, Princeton University, Princeton NJ 08544 (USA)
| | - Adam Reinhold
- Department of Chemistry, Princeton University, Princeton NJ 08544 (USA)
| | | | - Matthew J. Bird
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973 (USA)
| | - Robert R. Knowles
- Department of Chemistry, Princeton University, Princeton NJ 08544 (USA)
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92
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Volchek VV, Kompankov NB, Sokolov MN, Abramov PA. Proton Affinity in the Chemistry of Beta-Octamolybdate: HPLC-ICP-AES, NMR and Structural Studies. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238368. [PMID: 36500457 PMCID: PMC9738851 DOI: 10.3390/molecules27238368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 11/23/2022] [Accepted: 11/25/2022] [Indexed: 12/05/2022]
Abstract
The affinity of [β-Mo8O26]4- toward different proton sources has been studied in various conditions. The proposed sites for proton coordination were highlighted with single crystal X-ray diffraction (SCXRD) analysis of (Bu4N)3[β-{Ag(py-NH2)Mo8O26]}] (1) and from analysis of reported structures. Structural rearrangement of [β-Mo8O26]4- as a direct response to protonation was studied in solution with 95Mo NMR and HPLC-ICP-AES techniques. A new type of proton transfer reaction between (Bu4N)4[β-Mo8O26] and (Bu4N)4H2[V10O28] in DMSO results in both polyoxometalates transformation into [V2Mo4O19]4-, which was confirmed by the 95Mo, 51V NMR and HPLC-ICP-AES techniques. The same type of reaction with [H4SiW12O40] in DMSO leads to metal redistribution with formation of [W2Mo4O19]2-.
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Affiliation(s)
- Victoria V. Volchek
- Nikolaev Institute of Inorganic Chemistry SB RAS, 3 Akad. Lavrentiev Ave., 630090 Novosibirsk, Russia
| | - Nikolay B. Kompankov
- Nikolaev Institute of Inorganic Chemistry SB RAS, 3 Akad. Lavrentiev Ave., 630090 Novosibirsk, Russia
| | - Maxim N. Sokolov
- Nikolaev Institute of Inorganic Chemistry SB RAS, 3 Akad. Lavrentiev Ave., 630090 Novosibirsk, Russia
| | - Pavel A. Abramov
- Nikolaev Institute of Inorganic Chemistry SB RAS, 3 Akad. Lavrentiev Ave., 630090 Novosibirsk, Russia
- Institute of Natural Sciences and Mathematics, Ural Federal University Named after B.N. Yeltsin, 620075 Ekaterinburg, Russia
- Correspondence:
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93
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Boyd EA, Peters JC. Sm(II)-Mediated Proton-Coupled Electron Transfer: Quantifying Very Weak N-H and O-H Homolytic Bond Strengths and Factors Controlling Them. J Am Chem Soc 2022; 144:21337-21346. [PMID: 36346706 PMCID: PMC10281198 DOI: 10.1021/jacs.2c09580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Coordination of alcohols to the single-electron reductant samarium diiodide (SmI2) results in substantial O-H bond weakening, affording potent proton-coupled electron transfer (PCET) reagents. However, poorly defined speciation of SmI2 in tetrahydrofuran (THF)/alcohol mixtures limits reliable thermodynamic analyses of such systems. Rigorous determination of bond dissociation free energy (BDFE) values in such Sm systems, important to evaluating their reactivity profiles, motivates studies of model Sm systems where contributing factors can be teased apart. Here, a bulky and strongly chelating macrocyclic ligand ((tBu2ArOH)2Me2cyclam) maintains solubility, eliminates dimerization pathways, and facilitates clean electrochemical behavior in a well-defined functional model for the PCET reactivity of SmII with coordinating proton sources. Direct measurement of thermodynamic parameters enables reliable experimental estimation of the BDFEs in 2-pyrrolidone and MeOH complexes of ((tBu2ArO)2Me2cyclam)SmII, thereby revealing exceptionally weak N-H and O-H BDFEs of 27.2 and <24.1 kcal mol-1, respectively. Expanded thermochemical cycles reveal that this bond weakening stems from the very strongly reducing SmII center and the formation of strong SmIII-alkoxide (and -pyrrolidonate) interactions in the PCET products. We provide a detailed analysis comparing these BDFE values with those that have been put forward for SmI2 in THF in the presence of related proton donors. We suggest that BDFE values for the latter systems may in fact be appreciably higher than the system described herein. Finally, protonation and electrochemical reduction steps necessary for the regeneration of the PCET donors from SmIII-alkoxides are demonstrated, pointing to future strategies aimed at achieving (electro)catalytic turnover using SmII-based PCET reagents.
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Affiliation(s)
- Emily A Boyd
- Division of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), Pasadena, California 91125, United States
| | - Jonas C Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), Pasadena, California 91125, United States
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94
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Cooney SE, Fertig AA, Buisch MR, Brennessel WW, Matson EM. Coordination-induced bond weakening of water at the surface of an oxygen-deficient polyoxovanadate cluster. Chem Sci 2022; 13:12726-12737. [PMID: 36519047 PMCID: PMC9645371 DOI: 10.1039/d2sc04843d] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 10/10/2022] [Indexed: 10/19/2023] Open
Abstract
Hydrogen-atom (H-atom) transfer at the surface of heterogeneous metal oxides has received significant attention owing to its relevance in energy conversion and storage processes. Here, we present the synthesis and characterization of an organofunctionalized polyoxovanadate cluster, (calix)V6O5(OH2)(OMe)8 (calix = 4-tert-butylcalix[4]arene). Through a series of equilibrium studies, we establish the BDFE(O-H)avg of the aquo ligand as 62.4 ± 0.2 kcal mol-1, indicating substantial bond weaking of water upon coordination to the cluster surface. Subsequent kinetic isotope effect studies and Eyring analysis indicate the mechanism by which the hydrogenation of organic substrates occurs proceeds through a concerted proton-electron transfer from the aquo ligand. Atomistic resolution of surface reactivity presents a novel route of hydrogenation reactivity from metal oxide surfaces through H-atom transfer from surface-bound water molecules.
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Affiliation(s)
- Shannon E Cooney
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
| | - Alex A Fertig
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
| | | | | | - Ellen M Matson
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
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95
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Agarwal RG, Mayer JM. Coverage-Dependent Rate-Driving Force Relationships: Hydrogen Transfer from Cerium Oxide Nanoparticle Colloids. J Am Chem Soc 2022; 144:20699-20709. [DOI: 10.1021/jacs.2c07988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Rishi G. Agarwal
- Department of Chemistry, Yale University, New Haven, Connecticut06520-8107, United States
| | - James M. Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut06520-8107, United States
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96
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Johansen CM, Boyd EA, Peters JC. Catalytic transfer hydrogenation of N 2 to NH 3 via a photoredox catalysis strategy. SCIENCE ADVANCES 2022; 8:eade3510. [PMID: 36288295 PMCID: PMC9604530 DOI: 10.1126/sciadv.ade3510] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 09/02/2022] [Indexed: 06/16/2023]
Abstract
Inspired by momentum in applications of reductive photoredox catalysis to organic synthesis, photodriven transfer hydrogenations toward deep (>2 e-) reductions of small molecules are attractive compared to using harsh chemical reagents. Noteworthy in this context is the nitrogen reduction reaction (N2RR), where a synthetic photocatalyst system had yet to be developed. Noting that a reduced Hantzsch ester (HEH2) and related organic structures can behave as 2 e-/2 H+ photoreductants, we show here that, when partnered with a suitable catalyst (Mo) under blue light irradiation, HEH2 facilitates delivery of successive H2 equivalents for the 6 e-/6 H+ catalytic reduction of N2 to NH3; this catalysis is enhanced by addition of a photoredox catalyst (Ir). Reductions of additional substrates (nitrate and acetylene) are also described.
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97
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Hybrid bilayer membranes as platforms for biomimicry and catalysis. Nat Rev Chem 2022; 6:862-880. [PMID: 37117701 DOI: 10.1038/s41570-022-00433-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2022] [Indexed: 11/08/2022]
Abstract
Hybrid bilayer membrane (HBM) platforms represent an emerging nanoscale bio-inspired interface that has broad implications in energy catalysis and smart molecular devices. An HBM contains multiple modular components that include an underlying inorganic surface with a biological layer appended on top. The inorganic interface serves as a support with robust mechanical properties that can also be decorated with functional moieties, sensing units and catalytic active sites. The biological layer contains lipids and membrane-bound entities that facilitate or alter the activity and selectivity of the embedded functional motifs. With their structural complexity and functional flexibility, HBMs have been demonstrated to enhance catalytic turnover frequency and regulate product selectivity of the O2 and CO2 reduction reactions, which have applications in fuel cells and electrolysers. HBMs can also steer the mechanistic pathways of proton-coupled electron transfer (PCET) reactions of quinones and metal complexes by tuning electron and proton delivery rates. Beyond energy catalysis, HBMs have been equipped with enzyme mimics and membrane-bound redox agents to recapitulate natural energy transport chains. With channels and carriers incorporated, HBM sensors can quantify transmembrane events. This Review serves to summarize the major accomplishments achieved using HBMs in the past decade.
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98
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Dunn PL, Barona M, Johnson SI, Raugei S, Bullock RM. Hydrogen Atom Abstraction from an Os II(NH 3) 2 Complex Generates an Os IV(NH 2) 2 Complex: Experimental and Computational Analysis of the N-H Bond Dissociation Free Energies and Reactivity. Inorg Chem 2022; 61:15325-15334. [PMID: 36121917 DOI: 10.1021/acs.inorgchem.2c00708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Double hydrogen atom abstraction from (TMP)OsII(NH3)2 (TMP = tetramesitylporphyrin) with phenoxyl or nitroxyl radicals leads to (TMP)OsIV(NH2)2. This unusual bis(amide) complex is diamagnetic and displays an N-H resonance at 12.0 ppm in its 1H NMR spectrum. 1H-15N correlation experiments identified a 15N NMR spectroscopic resonance signal at -267 ppm. Experimental reactivity studies and density functional theory calculations support relatively weak N-H bonds of 73.3 kcal/mol for (TMP)OsII(NH3)2 and 74.2 kcal/mol for (TMP)OsIII(NH3)(NH2). Cyclic voltammetry experiments provide an estimate of the pKa of [(TMP)OsIII(NH3)2]+. In the presence of Barton's base, a current enhancement is observed at the Os(III/II) couple, consistent with an ECE event. Spectroscopic experiments confirmed (TMP)OsIV(NH2)2 as the product of bulk electrolysis. Double hydrogen atom abstraction is influenced by π donation from the amides of (TMP)OsIV(NH2)2 into the d orbitals of the Os center, favoring the formation of (TMP)OsIV(NH2)2 over N-N coupling. This π donation leads to a Jahn-Teller distortion that splits the energy levels of the dxz and dyz orbitals of Os, results in a low-spin electron configuration, and leads to minimal aminyl character on the N atoms, rendering (TMP)OsIV(NH2)2 unreactive toward amide-amide coupling.
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Affiliation(s)
- Peter L Dunn
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Melissa Barona
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Samantha I Johnson
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Simone Raugei
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - R Morris Bullock
- Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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99
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Cypcar AD, Kerr TA, Yang JY. Thermochemical Studies of Nickel Hydride Complexes with Cationic Ligands in Aqueous and Organic Solvents. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andrew D. Cypcar
- Department of Chemistry, University of California, Irvine, California 92697, United States
| | - Tyler A. Kerr
- Department of Chemistry, University of California, Irvine, California 92697, United States
| | - Jenny Y. Yang
- Department of Chemistry, University of California, Irvine, California 92697, United States
- Physical Sciences Division, Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
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100
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Wu T, Rajabimoghadam K, Puri A, Hebert DD, Qiu YL, Eichelberger S, Siegler MA, Swart M, Hendrich MP, Garcia-Bosch I. A 4H +/4e - Electron-Coupled-Proton Buffer Based on a Mononuclear Cu Complex. J Am Chem Soc 2022; 144:16905-16915. [PMID: 36083845 PMCID: PMC10123533 DOI: 10.1021/jacs.2c05454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this research article, we describe a 4H+/4e- electron-coupled-proton buffer (ECPB) based on Cu and a redox-active ligand. The protonated/reduced ECPB (complex 1: [Cu(8H+/14e-)]1+), consisting of CuI with 2 equiv of the ligand (catLH4: 1,1'-(4,5-dimethoxy-1,2-phenylene)bis(3-(tert-butyl)urea)), reacted with H+/e- acceptors such as O2 to generate the deprotonated/oxidized ECPB. The resulting compound, (complex 5: [Cu(4H+/10e-)]1+), was characterized by X-ray diffraction analysis, nuclear magnetic resonance (1H-NMR), and density functional theory, and it is electronically described as a cuprous bis(benzoquinonediimine) species. The stoichiometric 4H+/4e- reduction of 5 was carried out with H+/e- donors to generate 1 (CuI and 2 equiv of catLH4) and the corresponding oxidation products. The 1/5 ECPB system catalyzed the 4H+/4e- reduction of O2 to H2O and the dehydrogenation of organic substrates in a decoupled (oxidations and reductions are separated in time and space) and a coupled fashion (oxidations and reductions coincide in time and space). Mechanistic analysis revealed that upon reductive protonation of 5 and oxidative deprotonation of 1, fast disproportionation reactions regenerate complexes 5 and 1 in a stoichiometric fashion to maintain the ECPB equilibrium.
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Affiliation(s)
- Tong Wu
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | | | - Ankita Puri
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - David D Hebert
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yi Lin Qiu
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Sidney Eichelberger
- Department of Chemistry, Southern Methodist University, Dallas, Texas 75275, United States
| | - Maxime A Siegler
- Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Marcel Swart
- University of Girona, IQCC, Campus Montilivi (Cie#x300;ncies), 17003 Girona, Spain.,ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Michael P Hendrich
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Isaac Garcia-Bosch
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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