1
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Zhang YK, Zhao L, Xie WJ, Li HR, He LN. Mononuclear Iron Pyridinethiolate Complex Promoted CO 2 Photoreduction via Rapid Intramolecular Electron Transfer. CHEMSUSCHEM 2024; 17:e202400090. [PMID: 38426643 DOI: 10.1002/cssc.202400090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/19/2024] [Accepted: 03/01/2024] [Indexed: 03/02/2024]
Abstract
Designing earth-abundant metal complexes as efficient molecular photocatalysts for visible light-driven CO2 reduction is a key challenge in artificial photosynthesis. Here, we demonstrated the first example of a mononuclear iron pyridine-thiolate complex that functions both as a photosensitizer and catalyst for CO2 reduction. This single-component bifunctional molecular photocatalyst efficiently reduced CO2 to formate and CO with a total turnover number (TON) of 46 and turnover frequency (TOF) of 11.5 h-1 in 4 h under visible light irradiation. Notably, the quantum yield was determined to be 8.4 % for the generation of formate and CO at 400 nm. Quenching experiments indicate that high photocatalytic activity is mainly attributed to the rapid intramolecular quenching protocol. The mechanism investigation by DFT calculation and electrochemical studies revealed that the protonation of Febpy(pyS)2 is indispensable step for photocatalytic CO2 reduction.
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Affiliation(s)
- Yong-Kang Zhang
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China
| | - Lan Zhao
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China
| | - Wen-Jun Xie
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China
| | - Hong-Ru Li
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China
- College of Pharmacy, Nankai University, Tianjin, 300350, P. R. China
| | - Liang-Nian He
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China
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2
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Jung H, Choi J, Kim D, Lee JH, Ihee H, Kim D, Chang S. Photoinduced Group Transposition via Iridium-Nitrenoid Leading to Amidative Inner-Sphere Aryl Migration. Angew Chem Int Ed Engl 2024:e202408123. [PMID: 38871650 DOI: 10.1002/anie.202408123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 06/13/2024] [Accepted: 06/13/2024] [Indexed: 06/15/2024]
Abstract
We herein report a fundamental mechanistic investigation into photochemical metal-nitrenoid generation and inner-sphere transposition reactivity using organometallic photoprecursors. By designing Cp*Ir(hydroxamate)(Ar) complexes, we induced photo-initiated ligand activation, allowing us to explore the amidative σ(Ir-aryl) migration reactivity. A combination of experimental mechanistic studies, femtosecond transient absorption spectroscopy, and density functional theory (DFT) calculations revealed that the metal-to-ligand charge transfer enables the σ(N-O) cleavage, followed by Ir-acylnitrenoid generation. The final inner-sphere σ(Ir-aryl) group migration results in a net amidative group transposition.
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Affiliation(s)
- Hoimin Jung
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Jungkweon Choi
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Daniel Kim
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Jeong Hoon Lee
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Hyotcherl Ihee
- Center for Advanced Reaction Dynamics, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Dongwook Kim
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Sukbok Chang
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
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3
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Cloward IN, Liu T, Rose J, Jurado T, Bonn AG, Chambers MB, Pitman CL, Ter Horst MA, Miller AJM. Catalyst self-assembly accelerates bimetallic light-driven electrocatalytic H 2 evolution in water. Nat Chem 2024; 16:709-716. [PMID: 38528106 DOI: 10.1038/s41557-024-01483-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 02/21/2024] [Indexed: 03/27/2024]
Abstract
Hydrogen evolution is an important fuel-generating reaction that has been subject to mechanistic debate about the roles of monometallic and bimetallic pathways. The molecular iridium catalysts in this study undergo photoelectrochemical dihydrogen (H2) evolution via a bimolecular mechanism, providing an opportunity to understand the factors that promote bimetallic H-H coupling. Covalently tethered diiridium catalysts evolve H2 from neutral water faster than monometallic catalysts, even at lower overpotential. The unexpected origin of this improvement is non-covalent supramolecular self-assembly into nanoscale aggregates that efficiently harvest light and form H-H bonds. Monometallic catalysts containing long-chain alkane substituents leverage the self-assembly to evolve H2 from neutral water at low overpotential and with rates close to the expected maximum for this light-driven water splitting reaction. Design parameters for holding multiple catalytic sites in close proximity and tuning catalyst microenvironments emerge from this work.
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Affiliation(s)
- Isaac N Cloward
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Tianfei Liu
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- State Key Laboratory of Elemento-organic Chemistry, College of Chemistry, Nankai University, Tianjin, China
| | - Jamie Rose
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Tamara Jurado
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Annabell G Bonn
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Matthew B Chambers
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Catherine L Pitman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Marc A Ter Horst
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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4
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Sonea A, Warren JJ. Assembling the pieces to improve catalysis. Nat Chem 2024; 16:678-679. [PMID: 38641679 DOI: 10.1038/s41557-024-01513-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2024]
Affiliation(s)
- Ana Sonea
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada.
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5
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Song D, Xu W, He W, Li C, Yang J, Li J, Wang N. Selective Integrating Molecular Catalytic Units into Bipyridine-Based Covalent Organic Frameworks for Specific Photocatalytic Fuel Production. Inorg Chem 2024; 63:3444-3451. [PMID: 38331715 DOI: 10.1021/acs.inorgchem.3c04158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Molecular metal compounds have demonstrated excellent catalytic activity and product selectivity in the H2 evolution reaction (HER) and the CO2 reduction reaction (CO2RR). The heterogenization of molecular catalysts is regarded as an effective approach to improve their applicability. In this work, the molecular catalytic units [Cp*Ir(Bpy)Cl]+ and [Ru(Bpy)(CO)2Cl2] are constructed in situ on the bipyridine sites of the covalent organic framework for photocatalytic HER and CO2RR, respectively. Inheriting the impressive performance of molecular catalysts, the functionalized TpBpy-M exhibits excellent catalytic activity and product selectivity. Under visible light irradiation, the H2 production rate of TpBpy-Ir is about 760 μmol g-1 h-1, which is 6.7 times higher than that of TpBpy without built-in catalytic sites. Also, the HCOOH production rate of TpBpy-Ru is 271 μmol g-1 h-1, with an impressive selectivity of 88%. Control experiments validated that this improvement is attributed to the incorporation of molecular catalytic units into the framework. Photoluminescence spectroscopy measurements and theoretical calculation consistently demonstrate that, under illumination, the photosensitizer [Ru(Bpy)3]Cl2 is excited and transfers electrons to the catalytic sites in TpBpy-M, which then catalyzes the reduction of H+ and CO2.
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Affiliation(s)
- Dengmeng Song
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, China
| | - Wenhua Xu
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, China
| | - Wei He
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, China
| | - Chengbo Li
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, China
| | - Jing Yang
- College of Health Science and Environmental Engineering, Shenzhen Technology University, Shenzhen 518118, China
| | - Jun Li
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, China
| | - Ning Wang
- Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an 710069, China
- Shaanxi Key Laboratory for Carbon Neutral Technology, Northwest University, Xi'an 710127, China
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6
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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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7
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Hidalgo N, Moreno JJ, García‐Rubio I, Campos J. Enhanced Dihydrogen Activation by Mononuclear Iridium(II) Compounds: A Mechanistic Study. Angew Chem Int Ed Engl 2022; 61:e202206831. [PMID: 35737594 PMCID: PMC9545596 DOI: 10.1002/anie.202206831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Nereida Hidalgo
- Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA) Consejo Superior de Investigaciones Científicas (CSIC) Universidad de Sevilla Avenida Américo Vespucio 49 41092 Sevilla Spain
| | - Juan José Moreno
- Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA) Consejo Superior de Investigaciones Científicas (CSIC) Universidad de Sevilla Avenida Américo Vespucio 49 41092 Sevilla Spain
| | - Inés García‐Rubio
- Centro Universitario de la Defensa Ctra de Huesca s/n 50090 Zaragoza Spain
- Department of Condensed Matter Physics Faculty of Sciences University of Zaragoza Calle Pedro Cerbuna 50009 Zaragoza Spain
| | - Jesús Campos
- Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA) Consejo Superior de Investigaciones Científicas (CSIC) Universidad de Sevilla Avenida Américo Vespucio 49 41092 Sevilla Spain
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8
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Hidalgo N, Moreno JJ, Garcia-Rubio I, Campos J. Enhanced Dihydrogen Activation by Mononuclear Iridium(II) Compounds: A Mechanistic Study. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202206831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Nereida Hidalgo
- CSIC: Consejo Superior de Investigaciones Cientificas IIQ SPAIN
| | - Juan J Moreno
- CSIC: Consejo Superior de Investigaciones Cientificas IIQ SPAIN
| | - Ines Garcia-Rubio
- Universidad de Zaragoza Department of Condensed Matter Physics SPAIN
| | - Jesus Campos
- Consejo Superior de Investigaciones Cientificas Institute of Chemical Research Av. Americo Vespucio 49, Isla de la 41092 Sevilla SPAIN
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9
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Mejuto C, Ibáñez-Ibáñez L, Guisado-Barrios G, Mata JA. Visible-Light-Promoted Iridium(III)-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles at Room Temperature. ACS Catal 2022; 12:6238-6245. [PMID: 35633898 PMCID: PMC9128065 DOI: 10.1021/acscatal.2c01224] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/29/2022] [Indexed: 12/14/2022]
Abstract
![]()
An effective visible-light-promoted
iridium(III)-catalyzed hydrogen
production from N-heterocycles is described. A single iridium complex
constitutes the photocatalytic system playing a dual task, harvesting
visible-light and facilitating C–H cleavage and H2 formation at room temperature and without additives. The presence
of a chelating C–N ligand combining a mesoionic carbene ligand
along with an amido functionality in the IrIII complex
is essential to attain the photocatalytic transformation. Furthermore,
the IrIII complex is also an efficient catalyst for the
thermal reverse process under mild conditions, positioning itself
as a proficient candidate for liquid organic hydrogen carrier technologies
(LOHCs). Mechanistic studies support a light-induced formation of
H2 from the Ir–H intermediate as the operating mode
of the iridium complex.
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Affiliation(s)
- Carmen Mejuto
- Institute of Advanced Materials (INAM), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universitat Jaume I, Avda. Sos Baynat s/n, 12006 Castellón, Spain
| | - Laura Ibáñez-Ibáñez
- Institute of Advanced Materials (INAM), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universitat Jaume I, Avda. Sos Baynat s/n, 12006 Castellón, Spain
| | - Gregorio Guisado-Barrios
- Departamento de Química Inorgánica. Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - Jose A. Mata
- Institute of Advanced Materials (INAM), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universitat Jaume I, Avda. Sos Baynat s/n, 12006 Castellón, Spain
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10
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11
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Park Y, Tian L, Kim S, Pabst TP, Kim J, Scholes GD, Chirik PJ. Visible-Light-Driven, Iridium-Catalyzed Hydrogen Atom Transfer: Mechanistic Studies, Identification of Intermediates, and Catalyst Improvements. JACS AU 2022; 2:407-418. [PMID: 35252990 PMCID: PMC8889617 DOI: 10.1021/jacsau.1c00460] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Indexed: 06/14/2023]
Abstract
The harvesting of visible light is a powerful strategy for the synthesis of weak chemical bonds involving hydrogen that are below the thermodynamic threshold for spontaneous H2 evolution. Piano-stool iridium hydride complexes are effective for the blue-light-driven hydrogenation of organic substrates and contra-thermodynamic dearomative isomerization. In this work, a combination of spectroscopic measurements, isotopic labeling, structure-reactivity relationships, and computational studies has been used to explore the mechanism of these stoichiometric and catalytic reactions. Photophysical measurements on the iridium hydride catalysts demonstrated the generation of long-lived excited states with principally metal-to-ligand charge transfer (MLCT) character. Transient absorption spectroscopic studies with a representative substrate, anthracene revealed a diffusion-controlled dynamic quenching of the MLCT state. The triplet state of anthracene was detected immediately after the quenching events, suggesting that triplet-triplet energy transfer initiated the photocatalytic process. The key role of triplet anthracene on the post-energy transfer step was further demonstrated by employing photocatalytic hydrogenation with a triplet photosensitizer and a HAT agent, hydroquinone. DFT calculations support a concerted hydrogen atom transfer mechanism in lieu of stepwise electron/proton or proton/electron transfer pathways. Kinetic monitoring of the deactivation channel established an inverse kinetic isotope effect, supporting reversible C(sp2)-H reductive coupling followed by rate-limiting ligand dissociation. Mechanistic insights enabled design of a piano-stool iridium hydride catalyst with a rationally modified supporting ligand that exhibited improved photostability under blue light irradiation. The complex also provided improved catalytic performance toward photoinduced hydrogenation with H2 and contra-thermodynamic isomerization.
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12
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Sang S, Unruh T, Demeshko S, Domenianni LI, van Leest NP, Marquetand P, Schneck F, Würtele C, de Zwart FJ, de Bruin B, González L, Vöhringer P, Schneider S. Photo-Initiated Cobalt-Catalyzed Radical Olefin Hydrogenation. Chemistry 2021; 27:16978-16989. [PMID: 34156122 PMCID: PMC9292329 DOI: 10.1002/chem.202101705] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Indexed: 11/30/2022]
Abstract
Outer‐sphere radical hydrogenation of olefins proceeds via stepwise hydrogen atom transfer (HAT) from transition metal hydride species to the substrate. Typical catalysts exhibit M−H bonds that are either too weak to efficiently activate H2 or too strong to reduce unactivated olefins. This contribution evaluates an alternative approach, that starts from a square‐planar cobalt(II) hydride complex. Photoactivation results in Co−H bond homolysis. The three‐coordinate cobalt(I) photoproduct binds H2 to give a dihydrogen complex, which is a strong hydrogen atom donor, enabling the stepwise hydrogenation of both styrenes and unactivated aliphatic olefins with H2 via HAT.
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Affiliation(s)
- Sier Sang
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, 37077, Göttingen, Germany
| | - Tobias Unruh
- Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstrasse 12, 53117, Bonn, Germany
| | - Serhiy Demeshko
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, 37077, Göttingen, Germany
| | - Luis I Domenianni
- Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstrasse 12, 53117, Bonn, Germany
| | - Nicolaas P van Leest
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Philipp Marquetand
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090, Vienna, Austria
| | - Felix Schneck
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, 37077, Göttingen, Germany
| | - Christian Würtele
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, 37077, Göttingen, Germany
| | - Felix J de Zwart
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Bas de Bruin
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Leticia González
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Straße 17, 1090, Vienna, Austria
| | - Peter Vöhringer
- Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstrasse 12, 53117, Bonn, Germany
| | - Sven Schneider
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, 37077, Göttingen, Germany
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13
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Affiliation(s)
- Caleb D. Fast
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235 United States
| | - Nathan D. Schley
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235 United States
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14
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Siewert I, Fokin I, Kuessner KT. Transition Metal Complex Catalyzed Photo- and Electrochemical (De)hydrogenations Involving C=O and C=N Bonds. SYNTHESIS-STUTTGART 2021. [DOI: 10.1055/a-1645-3254] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
AbstractHerein, we summarize the photo- and electrochemical protocols for dehydrogenation and hydrogenations involving carbonyl and imine functions. The three basic principles that have been explored to interconvert such moieties with transition metal complexes are discussed in detail and the substrate scope is evaluated. Furthermore, we describe some general thermodynamic and kinetic aspects of such electro- and photochemically driven reactions.1 Introduction2 Dehydrogenation Reactions2.1 Electrochemical Dehydrogenations Using High-Valent Metal Species2.2 Electrochemical Dehydrogenations Involving Metal Hydride species2.3 Photochemically Driven Dehydrogenation3 Hydrogenation Reactions3.1 Electrochemical Protocols3.2 Photochemical Protocols4 Conclusion5 Abbreviations
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Affiliation(s)
- Inke Siewert
- Institut für Anorganische Chemie, Universität Göttingen
- International Center for Advanced Energy Studies, Universität Göttingen
| | - Igor Fokin
- Institut für Anorganische Chemie, Universität Göttingen
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15
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Kaul N, Lomoth R. The Carbene Cannibal: Photoinduced Symmetry-Breaking Charge Separation in an Fe(III) N-Heterocyclic Carbene. J Am Chem Soc 2021; 143:10816-10821. [PMID: 34264638 PMCID: PMC8397313 DOI: 10.1021/jacs.1c03770] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
![]()
Photoinduced symmetry-breaking
charge separation (SB-CS) processes
offer the possibility of harvesting solar energy by electron transfer
between identical molecules. Here, we present the first case of direct
observation of bimolecular SB-CS in a transition metal complex, [FeIIIL2](PF6) (L = [phenyl(tris(3-methylimidazol-1-ylidene))borate]−). Photoexcitation of the complex in the visible region
results in the formation of a doublet ligand-to-metal charge transfer
(2LMCT) excited state (E0–0 = 2.13 eV), which readily reacts with the doublet ground state to
generate charge separated products, [FeIIL2]
and [FeIVL2]2+, with a measurable
cage escape yield. Known spectral signatures allow for unambiguous
identification of the products, whose formation and recombination
are monitored with transient absorption spectroscopy. The unusual
energetic landscape of [FeIIIL2]+, as reflected in its ground and excited state reduction potentials,
results in SB-CS being intrinsically exergonic (ΔGCS° ∼ −0.7 eV). This is in contrast
to most systems investigated in the literature, where ΔGCS° is close to zero, and the charge transfer
driven primarily by solvation effects. The study is therefore illustrative
for the utilization of the rich redox chemistry accessible in transition
metal complexes for the realization of SB-CS.
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Affiliation(s)
- Nidhi Kaul
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
| | - Reiner Lomoth
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
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16
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Kaphan DM, Brereton KR, Klet RC, Witzke RJ, Miller AJM, Mulfort KL, Delferro M, Tiede DM. Photocatalytic Transfer Hydrogenation in Water: Insight into Mechanism and Catalyst Speciation. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00133] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- David M. Kaphan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Kelsey R. Brereton
- Department of Chemistry, Pepperdine University, Malibu, California 90263, United States
| | - Rachel C. Klet
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Ryan J. Witzke
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Karen L. Mulfort
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Massimiliano Delferro
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - David M. Tiede
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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17
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Makvandi P, Baghbantaraghdari Z, Zhou W, Zhang Y, Manchanda R, Agarwal T, Wu A, Maiti TK, Varma RS, Smith BR. Gum polysaccharide/nanometal hybrid biocomposites in cancer diagnosis and therapy. Biotechnol Adv 2021; 48:107711. [PMID: 33592279 DOI: 10.1016/j.biotechadv.2021.107711] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 12/26/2020] [Accepted: 02/02/2021] [Indexed: 12/26/2022]
Abstract
Biopolymers are of prime importance among which gum polysaccharides hold an eminent standing owing to their high availability and non-toxic nature. Gum biopolymers offer a greener alternative to synthetic polymers and toxic chemicals in the synthesis of metal nanostructures. Metal nanostructures accessible via eco-friendly means endow astounding characteristics to gum-based biocomposites in the field of diagnosis and therapy towards cancer diseases. In this review, assorted approaches for the assembly of nanomaterials mediated by gum biopolymers are presented and their utility in cancer diagnosis and therapy, e.g., bioimaging, radiotherapy, and phototherapy, are deliberated to provide a groundwork for future stimulative research.
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Affiliation(s)
- Pooyan Makvandi
- Istituto Italiano di Tecnologia, Center for Materials Interface, Pontedera 56025, Pisa, Italy.
| | - Zahra Baghbantaraghdari
- Department of Chemical, Materials & Industrial Production Engineering, University of Naples Federico II, Naples 80125, Italy
| | - Wenxian Zhou
- Department of Orthopaedics, Zhejiang Provincial Key Laboratory of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Yapei Zhang
- Department of Biomedical Engineering, Institute for Quantitative Health Science & Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Romila Manchanda
- Department of Biomedical Engineering, Institute for Quantitative Health Science & Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Tarun Agarwal
- Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302, India
| | - Aimin Wu
- Department of Orthopaedics, Zhejiang Provincial Key Laboratory of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Tapas Kumar Maiti
- Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302, India
| | - Rajender S Varma
- Regional Centre of Advanced Technologies and Materials (RCPTM), Palacky University, Olomouc, Šlechtitelů 11, 783 71, Olomouc, Czech Republic.
| | - Bryan Ronain Smith
- Department of Biomedical Engineering, Institute for Quantitative Health Science & Engineering, Michigan State University, East Lansing, MI 48824, USA; Department of Radiology and the Molecular Imaging Program, Stanford University, Stanford, CA, 94305, USA.
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18
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Kuo JL, Goldberg KI. Metal/Ligand Proton Tautomerism Facilitates Dinuclear H 2 Reductive Elimination. J Am Chem Soc 2020; 142:21439-21449. [PMID: 33297680 DOI: 10.1021/jacs.0c10458] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using the doubly protic bis-pyrazole-pyridine ligand (N(NNH)2), we have synthesized an octahedral IrIII-H [HIr(κ3-N(NNH)(NN-))(CO)(tBuPy)]+ ([1-MH]+) from an IrI starting material. This hydride was generated by adding sufficient electron density to the metal center such that it became the thermodynamically preferred site of protonation. It was observed via UV-vis spectroscopy that [1-MH]+ establishes a [tBuPy] dependent equilibrium with a ligand protonated square-planar IrI [Ir(N(NNH)2)(CO)]+ ([2-LH]+). This example of metal/ligand proton tautomerism is unusual in that the position of the equilibrium can be controlled by the concentration of exogeneous ligand (i.e., tBuPy). This equilibrium was shown to be key to the reactivity of the IrIII-H; 2 equiv of [1-MH]+ release H2, converting to the IrII dimer [[Ir(N(NN-)(NNH))(CO)(tBuPy)]2]2+ ([7]2+) under mild conditions (observable at room temperature). Mechanistic evidence is presented to support that this dinuclear reductive elimination occurs by tautomerization of the metal hydride [1-MH]+ to a ligand protonated species [1-LH]+, from which ligand dissociation is facile, generating [2-LH]+. Subsequent reaction of [2-LH]+ with [1-MH]+ allows for production of H2 and the IrII dimer [7]2+. The tautomerization between the metal-hydride and the ligand protonated species provides a low energy pathway for ligand dissociation, opening the needed coordination site. The ability to control the interconversion between a metal-hydride and a ligand-protonated congener using an exogeneous ligand introduces a new strategy for catalyst design with proton responsive ligands.
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Affiliation(s)
- Jonathan L Kuo
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Karen I Goldberg
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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19
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Schreier MR, Pfund B, Guo X, Wenger OS. Photo-triggered hydrogen atom transfer from an iridium hydride complex to unactivated olefins. Chem Sci 2020; 11:8582-8594. [PMID: 34123118 PMCID: PMC8163408 DOI: 10.1039/d0sc01820a] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/27/2020] [Indexed: 12/18/2022] Open
Abstract
Many photoactive metal complexes can act as electron donors or acceptors upon photoexcitation, but hydrogen atom transfer (HAT) reactivity is rare. We discovered that a typical representative of a widely used class of iridium hydride complexes acts as an H-atom donor to unactivated olefins upon irradiation at 470 nm in the presence of tertiary alkyl amines as sacrificial electron and proton sources. The catalytic hydrogenation of simple olefins served as a test ground to establish this new photo-reactivity of iridium hydrides. Substrates that are very difficult to activate by photoinduced electron transfer were readily hydrogenated, and structure-reactivity relationships established with 12 different olefins are in line with typical HAT reactivity, reflecting the relative stabilities of radical intermediates formed by HAT. Radical clock, H/D isotope labeling, and transient absorption experiments provide further mechanistic insight and corroborate the interpretation of the overall reactivity in terms of photo-triggered hydrogen atom transfer (photo-HAT). The catalytically active species is identified as an Ir(ii) hydride with an IrII-H bond dissociation free energy around 44 kcal mol-1, which is formed after reductive 3MLCT excited-state quenching of the corresponding Ir(iii) hydride, i.e. the actual HAT step occurs on the ground-state potential energy surface. The photo-HAT reactivity presented here represents a conceptually novel approach to photocatalysis with metal complexes, which is fundamentally different from the many prior studies relying on photoinduced electron transfer.
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Affiliation(s)
- Mirjam R Schreier
- Department of Chemistry, University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Björn Pfund
- Department of Chemistry, University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Xingwei Guo
- Department of Chemistry, University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
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20
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Huang J, Gallucci JC, Turro C. Panchromatic dirhodium photocatalysts for dihydrogen generation with red light. Chem Sci 2020; 11:9775-9783. [PMID: 34094240 PMCID: PMC8162114 DOI: 10.1039/d0sc03114c] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A series of three dirhodium complexes cis-[Rh2(DPhB)2(bncn)2](BF4)2 (1, DPhB = diphenylbenzamidine; bncn = benzocinnoline), cis-[Rh2(DPhTA)2(bncn)2](BF4)2 (2, DPhTA = diphenyltriazenide), and cis-[Rh2(DPhF)2(bncn)2](BF4)2 (3, DPhF = N,N′-diphenylformamidinate) shown to act as single-molecule photocatalysts for H2 production was evaluated. Complexes 1–3 are able to generate H2 in the absence of any other catalyst in homogenous acidic solution upon irradiation with red light in the presence of the sacrificial electron donor BNAH (1-benzyl-1,4-dihydronicotinamide). The excited state of each complex is reductively quenched by BNAH, producing the corresponding one-electron reduced complex. The latter is also able to absorb a photon and oxidize another BNAH molecule, producing the doubly-reduced, activated form of the catalyst that is able to generate H2. The present work shows the effect of substitution on the bridging ligands on the driving force for reductive quenching and hydricity of the proposed active intermediate, both of which affect the efficiency of hydrogen production. Complexes 1–3 operate following a double reductive quenching mechanism and, importantly, are active with red light. This work lays the foundation for the design of single-molecule photocatalysts that operate from the ultraviolet to the near-infrared, such that solar photons throughout this entire range are harnessed and utilized for solar energy conversion. Three dirhodium complexes cis-[Rh2(DPhB)2(bncn)2](BF4)2, cis-[Rh2(DPhTA)2(bncn)2](BF4)2 and cis-[Rh2(DPhF)2(bncn)2](BF4)2 are shown to act as single-molecule photocatalysts for H2 production.![]()
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Affiliation(s)
- Jie Huang
- Department of Chemistry and Biochemistry, The Ohio State University Columbus OH 43210 USA
| | - Judith C Gallucci
- Department of Chemistry and Biochemistry, The Ohio State University Columbus OH 43210 USA
| | - Claudia Turro
- Department of Chemistry and Biochemistry, The Ohio State University Columbus OH 43210 USA
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21
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Stratakes BM, Miller AJM. H 2 Evolution at an Electrochemical “Underpotential” with an Iridium-Based Molecular Photoelectrocatalyst. ACS Catal 2020. [DOI: 10.1021/acscatal.0c02265] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Bethany M. Stratakes
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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22
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Barrett SM, Stratakes BM, Chambers MB, Kurtz DA, Pitman CL, Dempsey JL, Miller AJM. Mechanistic basis for tuning iridium hydride photochemistry from H 2 evolution to hydride transfer hydrodechlorination. Chem Sci 2020; 11:6442-6449. [PMID: 34094109 PMCID: PMC8152724 DOI: 10.1039/d0sc00422g] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 03/05/2020] [Indexed: 01/01/2023] Open
Abstract
The photochemistry of metal hydride complexes is dominated by H2 evolution, limiting access to reductive transformations based on photochemical hydride transfer. In this article, the innate H2 evolution photochemistry of the iridium hydride complexes [Cp*Ir(bpy-OMe)H]+ (1, bpy-OMe = 4,4'-dimethoxy-2,2'-bipyridine) and [Cp*Ir(bpy)H]+ (2, bpy = 2,2'-bipyridine) is diverted towards photochemical hydrodechlorination. Net hydride transfer from 1 and 2 to dichloromethane produces chloromethane with high selectivity and exceptional photochemical quantum yield (Φ ≤ 1.3). Thermodynamic and kinetic mechanistic studies are consistent with a non-radical-chain reaction sequence initiated by "self-quenching" electron transfer between excited state and ground state hydride complexes, followed by proton-coupled electron transfer (PCET) hydrodechlorination that outcompetes H-H coupling. This unique photochemical mechanism provides a new hope for the development of light-driven hydride transfer reactions.
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Affiliation(s)
- Seth M Barrett
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
- Department of Chemistry, Muskingum University New Concord OH 43762-1118 USA
| | - Bethany M Stratakes
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
| | - Matthew B Chambers
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
- Department of Chemistry, Louisiana State University Baton Rouge LA 70803-1804 USA
| | - Daniel A Kurtz
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
| | - Catherine L Pitman
- 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
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
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23
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Whittemore TJ, Xue C, Huang J, Gallucci JC, Turro C. Single-chromophore single-molecule photocatalyst for the production of dihydrogen using low-energy light. Nat Chem 2020; 12:180-185. [DOI: 10.1038/s41557-019-0397-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Accepted: 11/15/2019] [Indexed: 01/23/2023]
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24
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Boyd EA, Lionetti D, Henke WC, Day VW, Blakemore JD. Preparation, Characterization, and Electrochemical Activation of a Model [Cp*Rh] Hydride. Inorg Chem 2019; 58:3606-3615. [PMID: 30256096 DOI: 10.1021/acs.inorgchem.8b02160] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Monomeric half-sandwich rhodium hydride complexes are often proposed as intermediates in catalytic cycles, but relatively few such compounds have been isolated and studied, limiting understanding of their properties. Here, we report preparation and isolation of a monomeric rhodium(III) hydride complex bearing the pentamethylcyclopentadienyl (Cp*) and bis(diphenylphosphino)benzene (dppb) ligands. The hydride complex is formed rapidly upon addition of weak acid to a reduced precursor complex, Cp*Rh(dppb). Single-crystal X-ray diffraction data for the [Cp*Rh] hydride, which were previously unavailable for this class of compounds, provide evidence of the direct Rh-H interaction. Complementary infrared spectra show the Rh-H stretching frequency at 1986 cm-1. In contrast to results with other [Cp*Rh] complexes bearing diimine ligands, treatment of the isolated hydride with strong acid does not result in H2 evolution. Electrochemical studies reveal that the hydride complex can be reduced only at very negative potentials (ca. -2.5 V vs ferrocenium/ferrocene), resulting in Rh-H bond cleavage and H2 generation. These results are discussed in the context of catalytic H2 generation, and development of design rules for improved catalysts bearing the [Cp*] ligand.
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Affiliation(s)
- Emily A Boyd
- Department of Chemistry , University of Kansas , 1251 Wescoe Hall Drive , Lawrence , Kansas 66045 , United States
| | - Davide Lionetti
- Department of Chemistry , University of Kansas , 1251 Wescoe Hall Drive , Lawrence , Kansas 66045 , United States
| | - Wade C Henke
- Department of Chemistry , University of Kansas , 1251 Wescoe Hall Drive , Lawrence , Kansas 66045 , United States
| | - Victor W Day
- Department of Chemistry , University of Kansas , 1251 Wescoe Hall Drive , Lawrence , Kansas 66045 , United States
| | - James D Blakemore
- Department of Chemistry , University of Kansas , 1251 Wescoe Hall Drive , Lawrence , Kansas 66045 , United States
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25
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Kadassery KJ, Sethi K, Fanara PM, Lacy DC. CO-Photolysis-Induced H-Atom Transfer from MnIO–H Bonds. Inorg Chem 2019; 58:4679-4685. [DOI: 10.1021/acs.inorgchem.9b00322] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Karthika J. Kadassery
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Komal Sethi
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Paul M. Fanara
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - David C. Lacy
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
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26
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Pannwitz A, Wenger OS. Proton-coupled multi-electron transfer and its relevance for artificial photosynthesis and photoredox catalysis. Chem Commun (Camb) 2019; 55:4004-4014. [DOI: 10.1039/c9cc00821g] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Photoinduced PCET meets catalysis, and the accumulation of multiple redox equivalents is of key importance.
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Affiliation(s)
- Andrea Pannwitz
- Department of Chemistry
- University of Basel
- 4056 Basel
- Switzerland
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27
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Deaton JC, Taliaferro CM, Pitman CL, Czerwieniec R, Jakubikova E, Miller AJM, Castellano FN. Excited-State Switching between Ligand-Centered and Charge Transfer Modulated by Metal-Carbon Bonds in Cyclopentadienyl Iridium Complexes. Inorg Chem 2018; 57:15445-15461. [PMID: 30516977 DOI: 10.1021/acs.inorgchem.8b02753] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Three series of pentamethylcyclopentadienyl (Cp*) Ir(III) complexes with different bidentate ligands were synthesized and structurally characterized, [Cp*Ir(tpy)L] n+ (tpy = 2-tolylpyridinato; n = 0 or 1), [Cp*Ir(piq)L] n+ (piq = 1-phenylisoquinolinato; n = 0 or 1), and [Cp*Ir(bpy)L] m+ (bpy = 2,2'-bipyridine; m = 1 or 2), featuring a range of monodentate carbon-donor ligands within each series [L = 2,6-dimethylphenylisocyanide; 3,5-dimethylimidazol-2-ylidene (NHC); methyl)]. The spectroscopic and photophysical properties of these molecules and those of the photocatalyst [Cp*Ir(bpy)H]+ were examined to establish electronic structure-photophysical property relationships that engender productive photochemical reactivity of this hydride and its methyl analogue. The Ir(III) chromophores containing ancillary CNAr ligands exhibited features anticipated for predominantly ligand-centered (LC) excited states, and analogues bearing the NHC ancillary exhibited properties consistent with LC excited states containing a small admixture of metal-to-ligand charge-transfer (MLCT) character. However, the molecules featuring anionic and strongly σ-donating methyl or hydride ligands exhibited photophysical properties consistent with a high degree of CT character. Density functional theory calculations suggest that the lowest energy triplet states in these complexes are composed of a mixture of MLCT and ligand-to-ligand CT originating from both the Cp* and methyl or hydride ancillary ligands. The high degree of CT character in the triplet excited states of methyliridium complexes bearing C^N-cyclometalated ligands offer a striking contrast to the photophysical properties of pseudo-octahedral structures fac-Ir(C^N)3 or Ir(C^N)2(acac) that have lowest-energy triplet excited states characterized as primarily LC character with a more moderate MLCT admixture.
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Affiliation(s)
- Joseph C Deaton
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695-8204 , United States
| | - Chelsea M Taliaferro
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695-8204 , United States
| | - Catherine L Pitman
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States
| | - Rafał Czerwieniec
- Institut für Physikalische und Theoretische Chemie , Universität Regensburg , Universitätstrasse 31 , D-93040 Regensburg , Germany
| | - Elena Jakubikova
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695-8204 , United States
| | - Alexander J M Miller
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States
| | - Felix N Castellano
- Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695-8204 , United States
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28
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Huang T, Rountree ES, Traywick AP, Bayoumi M, Dempsey JL. Switching between Stepwise and Concerted Proton-Coupled Electron Transfer Pathways in Tungsten Hydride Activation. J Am Chem Soc 2018; 140:14655-14669. [PMID: 30362720 DOI: 10.1021/jacs.8b07102] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Catalytic processes to generate (or oxidize) fuels such as hydrogen are underpinned by multiple proton-coupled electron transfer (PCET) steps that are associated with the formation or activation of metal-hydride bonds. Fully understanding the detailed PCET mechanisms of metal hydride transformations holds promise for the rational design of energy-efficient catalysis. Here we investigate the detailed PCET mechanisms for the activation of the transition metal hydride complex CpW(CO)2(PMe3)H (Cp = cyclopentadienyl) using stopped-flow rapid mixing coupled with time-resolved optical spectroscopy. We reveal that all three limiting PCET pathways can be accessed by changing the free energy for elementary proton, electron, and proton-electron transfers through the choice of base and oxidant, with the concerted pathway occurring exclusively as a secondary parallel route. Through detailed kinetics analysis, we define free energy relationships for the kinetics of elementary reaction steps, which provide insight into the factors influencing reaction mechanism. Rate constants for proton transfer processes in the limiting stepwise pathways reveal a large reorganization energy associated with protonation/deprotonation of the metal center (λ = 1.59 eV) and suggest that sluggish proton transfer kinetics hinder access to a concerted route. Rate constants for concerted PCET indicate that the concerted routes are asynchronous. Additionally, through quantification of the relative contributions of parallel stepwise and concerted mechanisms toward net product formation, the influence of various reaction parameters on reactivity are identified. This work underscores the importance of understanding the PCET mechanism for controlling metal hydride reactivity, which could lead to superior catalyst design for fuel production and oxidation.
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Affiliation(s)
- Tao Huang
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States
| | - Eric S Rountree
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States
| | - Andrew P Traywick
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States
| | - Magd Bayoumi
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States
| | - Jillian L Dempsey
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States
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29
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Castellano FN. Editorial for the ACS Select Virtual Issue on Emerging Investigators in Inorganic Photochemistry and Photophysics. Inorg Chem 2018; 55:12483-12487. [PMID: 27989181 DOI: 10.1021/acs.inorgchem.6b02830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Felix N Castellano
- Department of Chemistry, North Carolina State University , Raleigh, North Carolina 27695-8204, United States
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30
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Adams RE, Grusenmeyer TA, Griffith AL, Schmehl RH. Transition metal hydride complexes as mechanistic models for proton reduction catalysis. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2018.02.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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31
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Taliaferro CM, Danilov EO, Castellano FN. Ultrafast Dynamics of the Metal-to-Ligand Charge Transfer Excited States of Ir(III) Proteo and Deutero Dihydrides. J Phys Chem A 2018; 122:4430-4436. [DOI: 10.1021/acs.jpca.8b02266] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chelsea M. Taliaferro
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Evgeny O. Danilov
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Felix N. Castellano
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
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32
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Huckaba AJ, Shirley H, Lamb RW, Guertin S, Autry S, Cheema H, Talukdar K, Jones T, Jurss JW, Dass A, Hammer NI, Schmehl RH, Webster CE, Delcamp JH. A Mononuclear Tungsten Photocatalyst for H2 Production. ACS Catal 2018. [DOI: 10.1021/acscatal.7b04242] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Aron J. Huckaba
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Hunter Shirley
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Robert W. Lamb
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Steve Guertin
- Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Shane Autry
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Hammad Cheema
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Kallol Talukdar
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Tanya Jones
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Jonah W. Jurss
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Amala Dass
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Nathan I. Hammer
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
| | - Russell H. Schmehl
- Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Charles Edwin Webster
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Jared H. Delcamp
- Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677, United States
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33
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Kagalwala HN, Chirdon DN, Mills IN, Budwal N, Bernhard S. Light-Driven Hydrogen Generation from Microemulsions Using Metallosurfactant Catalysts and Oxalic Acid. Inorg Chem 2017; 56:10162-10171. [DOI: 10.1021/acs.inorgchem.7b00463] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Husain N. Kagalwala
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Danielle N. Chirdon
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Isaac N. Mills
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Nikita Budwal
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Stefan Bernhard
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
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Affiliation(s)
- Catherine L. Pitman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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Xiao P, Wu D, Fang WH, Cui G. Mechanistic insights into the light-driven hydrogen evolution reaction from formic acid mediated by an iridium photocatalyst. Catal Sci Technol 2017. [DOI: 10.1039/c7cy00785j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electronic structure calculations shed important mechanistic light on light-driven hydrogen evolution from formic acid mediated by an iridium photocatalyst.
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Affiliation(s)
- Pin Xiao
- Key Laboratory of Theoretical and Computational Photochemistry
- Ministry of Education
- College of Chemistry
- Beijing Normal University
- Beijing 100875
| | - Dan Wu
- Key Laboratory of Theoretical and Computational Photochemistry
- Ministry of Education
- College of Chemistry
- Beijing Normal University
- Beijing 100875
| | - Wei-Hai Fang
- Key Laboratory of Theoretical and Computational Photochemistry
- Ministry of Education
- College of Chemistry
- Beijing Normal University
- Beijing 100875
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry
- Ministry of Education
- College of Chemistry
- Beijing Normal University
- Beijing 100875
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Brereton KR, Pitman CL, Cundari TR, Miller AJM. Solvent-Dependent Thermochemistry of an Iridium/Ruthenium H2 Evolution Catalyst. Inorg Chem 2016; 55:12042-12051. [DOI: 10.1021/acs.inorgchem.6b02223] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Kelsey R. Brereton
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Catherine L. Pitman
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Thomas R. Cundari
- Department
of Chemistry and CASCaM, University of North Texas, Denton, Texas 76203, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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