1
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Mondal S, Zhang W, Zhang S. Thermodynamics of Proton-Coupled Electron Transfer at Tricopper μ-Oxo/Hydroxo/Aqua Complexes. J Am Chem Soc 2024; 146:15036-15044. [PMID: 38770819 DOI: 10.1021/jacs.3c14420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Multicopper oxidases (MCOs) utilize a tricopper active site to reduce dioxygen to water through 4H+ 4e- proton-coupled electron transfer (PCET). Understanding the thermodynamics of PCET at a tricopper cluster is essential for elucidating how MCOs harness the oxidative power of O2 while mitigating oxidative damage. In this study, we determined the O-H bond dissociation free energies (BDFEs) and pKa values of a series of tricopper hydroxo and tricopper aqua complexes as synthetic models of the tricopper site in MCOs. Tricopper intermediates on the path of alternating electron and proton transfer (ET-PT-ET-PT-ET) have modest BDFE(O-H) values in the range of 53.0-57.1 kcal/mol. In contrast, those not on the path of ET-PT-ET-PT-ET display much higher (78.1 kcal/mol) or lower (44.7 kcal/mol) BDFE(O-H) values. Additionally, the pKa of bridging OH and OH2 motifs increase by 8-16 pKa units per oxidation state. The same oxidation state changes have a lesser impact on the pKa of N-H motif in the secondary coordination sphere, with an increase of ca. 5 pKa units per oxidation state. The steeper pKa increase of the tricopper center promotes proton transfer from the secondary coordination sphere. Overall, our study shed light on the PCET pathway least prone to decomposition, elucidating why tricopper centers are an optimal choice for promoting efficient oxygen reduction reaction.
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Affiliation(s)
- Saikat Mondal
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Weiyao Zhang
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Shiyu Zhang
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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2
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Medvedev JJ, Delva NH, Klinkova A. Mechanistic Analysis of Urea Electrooxidation Pathways: Key to Rational Catalyst Design. Chempluschem 2024; 89:e202300739. [PMID: 38346095 DOI: 10.1002/cplu.202300739] [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: 12/13/2023] [Revised: 02/07/2024] [Indexed: 02/29/2024]
Abstract
Urea electrolysis is an emerging approach to treating urea-enriched wastewater and an attractive alternative anodic process to the oxygen evolution reaction (OER) in electrochemical clean energy conversion and storage technologies (e. g., hydrogen production and CO2 electroreduction). While the thermodynamic potential for urea oxidation to dinitrogen is quite low compared to that of the OER, the catalysts reported to date require high overpotentials that far exceed those for the OER. Consequently, there is much room for improvement and rational catalyst design for the urea oxidation reaction (UOR). At the same time, due to the urea molecule having a more complex structure than water, UOR can lead to the formation of various products beyond the commonly assumed N2 and CO2. This concept article will critically assess recent efforts of the research community to decipher the formation mechanisms of UOR products focusing on the systematic analysis of the reaction selectivity. This work aims to analyze the current state of the art and identify existing gaps, providing an outlook for the future design of UOR catalysts with superior activity and selectivity by applying the knowledge of the molecular transformation mechanisms.
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Affiliation(s)
- Jury J Medvedev
- Department of Chemistry, University of Waterloo, 200 University Ave W, Waterloo, Ontario, Canada, N2L 3G1
| | - Nyhenflore H Delva
- Department of Chemistry, University of Waterloo, 200 University Ave W, Waterloo, Ontario, Canada, N2L 3G1
| | - Anna Klinkova
- Department of Chemistry, University of Waterloo, 200 University Ave W, Waterloo, Ontario, Canada, N2L 3G1
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3
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Cooney SE, Schreiber E, Ferrigno BM, Matson EM. O 2 reduction via proton-coupled electron transfer by a V(III) aquo on a polyoxovanadate-alkoxide cluster. Chem Commun (Camb) 2024; 60:5610-5613. [PMID: 38713068 DOI: 10.1039/d4cc01331j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
We report the transfer of H-atoms from a reduced polyoxovanadate alkoxide [nOct4N][V6O6(OH2)(OMe)12] via concerted proton-electron transfer. Oxygen reduction is compared between bridging and terminal O-H bonds revealing similar mechanisms, providing new insight to design criteria for metal-oxide electrocatalysts that faciliate oxygen reduction by concerted-proton electron transfer.
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Affiliation(s)
- Shannon E Cooney
- Department of Chemistry, University of Rochester, Rochester NY 14627, USA.
| | - Eric Schreiber
- Department of Chemistry, University of Rochester, Rochester NY 14627, USA.
| | - Baela M Ferrigno
- 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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4
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Wu T, Puri A, Qiu YL, Ye D, Sarma R, Wang Y, Kowalewski T, Siegler MA, Swart M, Garcia-Bosch I. Tuning the Thermochemistry and Reactivity of a Series of Cu-Based 4H +/4e - Electron-Coupled-Proton Buffers. Inorg Chem 2024; 63:9014-9025. [PMID: 38723621 PMCID: PMC11110016 DOI: 10.1021/acs.inorgchem.4c00835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/08/2024] [Accepted: 04/30/2024] [Indexed: 05/21/2024]
Abstract
Electron-coupled-proton buffers (ECPBs) store and deliver protons and electrons in a reversible fashion. We have recently reported an ECPB based on Cu and a redox-active ligand that promoted 4H+/4e- reversible transformations (J. Am. Chem. Soc. 2022, 144, 16905). Herein, we report a series of Cu-based ECPBs in which the ability of these to accept and/or donate H• equivalents can be tuned via ligand modification. The thermochemistry of the 4H+/4e- ECPB equilibrium was determined using open-circuit potential measurements. The reactivity of the ECPBs against proton-coupled electron transfer (PCET) reagents was also analyzed, and the results obtained were rationalized based on the thermochemical parameters. Experimental and computational analysis of the thermochemistry of the H+/e- transfers involved in the 4H+/4e- ECPB transformations found substantial differences between the stepwise (namely, BDFE1, BDFE2, BDFE3, and BDFE4) and average bond dissociation free energy values (BDFEavg.). Our analysis suggests that this "redox unleveling" is critical to promoting the disproportionation and ligand-exchange reactions involved in the 4H+/4e- ECPB equilibria. The difference in BDFEavg. within the series of Cu-based ECPBs was found to arise from a substantial change in the redox potential (E1/2) upon modification of the ligand scaffold, which is not fully compensated for by a change in the acidity/basicity (pKa), suggesting "thermochemical decompensation".
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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
| | - Yi Lin Qiu
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Daniel Ye
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Rajdeep Sarma
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yiwen Wang
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Tomasz Kowalewski
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | | | - Marcel Swart
- University
of Girona, Campus Montilivi (Ciències), Plaça de Sant Domènec, 17004 Girona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Isaac Garcia-Bosch
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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5
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Wei C, Zhang Y, Qu Y, Hua W, Jia Z, Lu J, Xie G, Xiao J, Hu H, Yang Y, Liu JQ, Bai J, Xue G. Dual Channel H 2O 2 Photosynthesis in Pure Water over S-Scheme Heterojunction Cs 3PMo 12/CC Boosted by Proton and Electron Reservoirs. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2401485. [PMID: 38712455 DOI: 10.1002/smll.202401485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 04/24/2024] [Indexed: 05/08/2024]
Abstract
Dual channel photo-driven H2O2 production in pure water on small-scale on-site setups is a promising strategy to provide low-concentrated H2O2 whenever needed. This process suffers, however, strongly from the fast recombination of photo-generated charge carriers and the sluggish oxidation process. Here, insoluble Keggin-type cesium phosphomolybdate Cs3PMo12O40 (abbreviated to Cs3PMo12) is introduced to carbonized cellulose (CC) to construct S-scheme heterojunction Cs3PMo12/CC. Dual channel H2O2 photosynthesis from both H2O oxidation and O2 reduction in pure water has been thus achieved with the production rate of 20.1 mmol L-1 gcat. -1 h-1, apparent quantum yield (AQY) of 2.1% and solar-to-chemical conversion (SCC) efficiency of 0.050%. H2O2 accumulative concentration reaches 4.9 mmol L-1. This high photocatalytic activity is guaranteed by unique features of Cs3PMo12/CC, namely, S-scheme heterojunction, electron reservoir, and proton reservoir. The former two enhance the separation of photo-generated charge carriers, while the latter speeds up the torpid oxidation process. In situ experiments reveal that H2O2 is formed via successive single-electron transfer in both channels. In real practice, exposing the reaction system under natural sunlight outdoors successfully results in 0.24 mmol L-1 H2O2. This work provides a key practical strategy for designing photocatalysts in modulating redox half-reactions in photosynthesis.
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Affiliation(s)
- Chong Wei
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry & Materials Science, Northwest University, 1 Xuefu Ave., Xi'an, 710127, China
| | - Yu Zhang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry & Materials Science, Northwest University, 1 Xuefu Ave., Xi'an, 710127, China
| | - Yunteng Qu
- State Key Laboratory of Photoelectric Technology and Functional Materials, International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Institute of Photonics & PhotonTechnology, Northwest University, Xi'an, 710069, China
- Shaanxi Key Laboratory for Carbon Neutral Technology, Northwest University, Xi'an, 710127, China
| | - Wenbo Hua
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry & Materials Science, Northwest University, 1 Xuefu Ave., Xi'an, 710127, China
| | - Zixian Jia
- SINOPEC Dalian Research Institute of Petroleum and Petrochemicals Co., Ltd, Dalian, 116045, China
| | - Jiangbo Lu
- School of Physics & Information Technology, Shaanxi Normal University, Xi'an, Shaanxi, 710062, China
| | - Gang Xie
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry & Materials Science, Northwest University, 1 Xuefu Ave., Xi'an, 710127, China
- Shaanxi Key Laboratory for Carbon Neutral Technology, Northwest University, Xi'an, 710127, China
| | - Jianming Xiao
- Department College of Materials Science and Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Huaiming Hu
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry & Materials Science, Northwest University, 1 Xuefu Ave., Xi'an, 710127, China
| | - Ying Yang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry & Materials Science, Northwest University, 1 Xuefu Ave., Xi'an, 710127, China
- Shaanxi Key Laboratory for Carbon Neutral Technology, Northwest University, Xi'an, 710127, China
| | - Ji-Quan Liu
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry & Materials Science, Northwest University, 1 Xuefu Ave., Xi'an, 710127, China
- Shaanxi Key Laboratory for Carbon Neutral Technology, Northwest University, Xi'an, 710127, China
| | - Jinbo Bai
- CentraleSupélec, ENS Paris-Saclay, CNRS, LMPS-Laboratoire de Mécanique Paris-Saclay, Université Paris-Saclay, 8-10 rue Joliot-Curie, Gif-sur-Yvette, 91190, France
| | - Ganglin Xue
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, College of Chemistry & Materials Science, Northwest University, 1 Xuefu Ave., Xi'an, 710127, China
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6
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Proe KR, Towarnicky A, Fertig A, Lu Z, Mpourmpakis G, Matson EM. Impact of Surface Ligand Identity and Density on the Thermodynamics of H Atom Uptake at Polyoxovanadate-Alkoxide Surfaces. Inorg Chem 2024; 63:7206-7217. [PMID: 38592922 DOI: 10.1021/acs.inorgchem.3c04435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
An understanding of how molecular structure influences the thermodynamics of H atom transfer is critical to designing efficient catalysts for reductive chemistries. Herein, we report experimental and theoretical investigations summarizing structure-function relationships of polyoxovanadate-alkoxides that influence bond dissociation free energies of hydroxide ligands located at the surface of the cluster. We evaluate the thermochemical descriptors of O-H bond strength for a series of clusters, namely [V6O13-x(OH)x(TRIOLR)2]-2 (x = 2, 4, 6; R = NO2, Me) and [V6O11-x(OMe)2(OH)x(TRIOLNO2)2]-2, via computational analysis and open circuit potential measurements. Our findings reveal that modifications to the TRIOL ligand (e.g., changing from the previously reported electron withdrawing nitro-backed ligand to the electron-donating methyl variant) have limited influence on the strength of surface O-H bonds as a result of near complete thermodynamic compensation in these systems (i.e., correlated changes in redox potential and cluster basicity). In contrast, changes in surface density of alkoxide ligands via direct alkoxylation of the polyoxovanadate-alkoxide surface result in measurable increases in bond dissociation free energies of surface O-H bonds for the mixed-valent derivatives. Our findings indicate that the extent of (de)localization of electron density across the cluster core has an impact on the bond dissociation free energies of surface O-H bonds across all oxidation states of the assembly.
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Affiliation(s)
- Kathryn R Proe
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Andreas Towarnicky
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Alex Fertig
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Zhou Lu
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Giannis Mpourmpakis
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Ellen M Matson
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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7
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Lu Z, Cooney SE, McKone JR, Matson EM. Selective Hydrogenation of Azobenzene to Hydrazobenzene via Proton-Coupled Electron Transfer from a Polyoxotungstate Cluster. JACS AU 2024; 4:1310-1314. [PMID: 38665657 PMCID: PMC11041919 DOI: 10.1021/jacsau.4c00127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 03/05/2024] [Accepted: 03/14/2024] [Indexed: 04/28/2024]
Abstract
In this report, we describe proton-coupled electron transfer (PCET) reactivity at the surface of the Keggin-type polyoxotungstate cluster [nBu4N]3[PWVI12O40] (PW12) in acetonitrile. Bond dissociation free energies (BDFEs) of the O-H groups generated upon reduction of PW12 in the presence of acid are determined through the construction of a potential-pKa diagram. The surface O-H bonds are found to be weak (BDFE(O-H)avg < 48 kcal mol-1), comparable to the BDFE of H2. This is consistent with the observed formation of H2 upon addition of a suitably strong organic acid, H2NPh2+ (pKa MeCN = 5.98), to the reduced form of the cluster. The one-electron reduced form of PW12 is isolated and used in conjunction with acid to realize the stoichiometric semihydrogenation of azobenzene via PCET from the surface of the reduced cluster.
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Affiliation(s)
- Zhou Lu
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Shannon E. Cooney
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - James R. McKone
- Departments
of Chemical and Petroleum Engineering and Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Ellen M. Matson
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
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8
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Quirós-Díez EP, Herreros-Lucas C, Vila-Fungueiriño JM, Vizcaíno-Anaya L, Sabater-Algarra Y, Giménez-López MDC. Boosting Oxygen Reduction Reaction Selectivity in Metal Nanoparticles with Polyoxometalates. SMALL METHODS 2024:e2301805. [PMID: 38517266 DOI: 10.1002/smtd.202301805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 03/06/2024] [Indexed: 03/23/2024]
Abstract
The lack of selectivity toward the oxygen reduction reaction (ORR) in metal nanoparticles can be linked to the generation of intermediates. This constitutes a crucial constraint on the performance of specific electrochemical devices, such as fuel cells and metal-air batteries. To boost selectivity of metal nanoparticles, a novel methodology that harnesses the unique electrocatalytic properties of polyoxometalates (POM) to scavenge undesired intermediates of the ORR (such as HO2 -) promoting selectivity is proposed. It involves the covalent functionalization of metal nanoparticle's surface with an electrochemically active capping layer containing a new sulfur-functionalized vanadium-based POM (AuNP@POM). To demonstrate this approach, preformed thiolate Au(111) nanoparticles with a relatively poor ORR selectivity are chosen. The dispersion of AuNP@POM on the surface of carbon nanofibers (CNF) enhances oxygen diffusion, and therefore the ORR activity. The resulting electrocatalyst (AuNP@POM/CNF) exhibits superior stability against impurities like methanol and a higher pH tolerance range compared to the standard commercial Pt/C. The work demonstrates for the first time, the use of a POM-based electrochemically active capping layer to switch on the selectivity of poorly selective gold nanoparticles, offering a promising avenue for the preparation of electrocatalyst materials with improved selectivity, performance, and stability for ORR-based devices.
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Affiliation(s)
- Eugenia Pilar Quirós-Díez
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Inorgánica, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain
| | - Carlos Herreros-Lucas
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Inorgánica, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain
| | - José Manuel Vila-Fungueiriño
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Física, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain
| | - Lucía Vizcaíno-Anaya
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Inorgánica, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain
| | - Yolanda Sabater-Algarra
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Inorgánica, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain
| | - María Del Carmen Giménez-López
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Inorgánica, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain
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9
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Cooney S, Walls MRA, Schreiber E, Brennessel WW, Matson EM. Heterometal Dopant Changes the Mechanism of Proton-Coupled Electron Transfer at the Polyoxovanadate-Alkoxide Surface. J Am Chem Soc 2024; 146:2364-2369. [PMID: 38241170 PMCID: PMC10835708 DOI: 10.1021/jacs.3c14054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/21/2024]
Abstract
The transfer of two H-atom equivalents to the titanium-doped polyoxovanadate-alkoxide, [TiV5O6(OCH3)13], results in the formation of a V(III)-OH2 site at the surface of the assembly. Incorporation of the group (IV) metal ion results in a weakening of the O-H bonds of [TiV5O5(OH2)(OCH3)13] in comparison to its homometallic congener, [V6O6(OH2)(OCH3)12], resembling more closely the thermodynamics reported for the one-electron reduced derivative, [V6O6(OH2)(OCH3)12]1-. An analysis of early time points of the reaction of [TiV5O6(OCH3)13] and 5,10-dihydrophenazine reveals the formation of an oxidized substrate, suggesting that proton-coupled electron transfer proceeds via initial electron transfer from substrate to cluster prior to proton transfer. These results demonstrate the profound influence of heterometal dopants on the mechanism of PCET with respect to the surface of the assembly.
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Affiliation(s)
- Shannon
E. Cooney
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - M. Rebecca A. Walls
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Eric Schreiber
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - William W. Brennessel
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Ellen M. Matson
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
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10
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Kessinger MC, Xu J, Cui K, Loague Q, Soudackov AV, Hammes-Schiffer S, Meyer GJ. Direct Evidence for a Sequential Electron Transfer-Proton Transfer Mechanism in the PCET Reduction of a Metal Hydroxide Catalyst. J Am Chem Soc 2024; 146:1742-1747. [PMID: 38193695 DOI: 10.1021/jacs.3c10742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
The proton-coupled electron transfer (PCET) mechanism for the reaction Mox-OH + e- + H+ → Mred-OH2 was determined through the kinetic resolution of the independent electron transfer (ET) and proton transfer (PT) steps. The reaction of interest was triggered by visible light excitation of [RuII(tpy)(bpy')H2O]2+, RuII-OH2, where tpy is 2,2':6',2″-terpyridine and bpy' is 4,4'-diaminopropylsilatrane-2,2'-bipyridine, anchored to In2O3:Sn (ITO) thin films in aqueous solutions. Interfacial kinetics for the PCET reduction reaction were quantified by nanosecond transient absorption spectroscopy as a function of solution pH and applied potential. Data acquired at pH = 5-10 revealed a stepwise electron transfer-proton transfer (ET-PT) mechanism, while kinetic measurements made below pKa(RuIII-OH/OH2) = 1.3 were used to study the analogous interfacial reaction, where electron transfer was the only mechanistic step. Analysis of this data with a recently reported multichannel kinetic model was used to construct a PCET zone diagram and supported the assignment of an ET-PT mechanism at pH = 5-10. Ultimately, this study represents a unique example among Mox-OH/Mred-OH2 reactivity where the protonation and oxidation states of the intermediate were kinetically and spectrally resolved to firmly establish the PCET mechanism.
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Affiliation(s)
- Matthew C Kessinger
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jeremiah Xu
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Kai Cui
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Quentin Loague
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Alexander V Soudackov
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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11
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Salazar Marcano DE, Savić ND, Declerck K, Abdelhameed SAM, Parac-Vogt TN. Reactivity of metal-oxo clusters towards biomolecules: from discrete polyoxometalates to metal-organic frameworks. Chem Soc Rev 2024; 53:84-136. [PMID: 38015569 DOI: 10.1039/d3cs00195d] [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: 11/29/2023]
Abstract
Metal-oxo clusters hold great potential in several fields such as catalysis, materials science, energy storage, medicine, and biotechnology. These nanoclusters of transition metals with oxygen-based ligands have also shown promising reactivity towards several classes of biomolecules, including proteins, nucleic acids, nucleotides, sugars, and lipids. This reactivity can be leveraged to address some of the most pressing challenges we face today, from fighting various diseases, such as cancer and viral infections, to the development of sustainable and environmentally friendly energy sources. For instance, metal-oxo clusters and related materials have been shown to be effective catalysts for biomass conversion into renewable fuels and platform chemicals. Furthermore, their reactivity towards biomolecules has also attracted interest in the development of inorganic drugs and bioanalytical tools. Additionally, the structural versatility of metal-oxo clusters allows for the efficiency and selectivity of the biomolecular reactions they promote to be readily tuned, thereby providing a pathway towards reaction optimization. The properties of the catalyst can also be improved through incorporation into solid supports or by linking metal-oxo clusters together to form Metal-Organic Frameworks (MOFs), which have been demonstrated to be powerful heterogeneous catalysts. Therefore, this review aims to provide a comprehensive and critical analysis of the state of the art on biomolecular transformations promoted by metal-oxo clusters and their applications, with a particular focus on structure-activity relationships.
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Affiliation(s)
| | - Nada D Savić
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.
| | - Kilian Declerck
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.
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12
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Peter CYM, Schreiber E, Proe KR, Matson EM. Surface ligand length influences kinetics of H-atom uptake in polyoxovanadate-alkoxide clusters. Dalton Trans 2023; 52:15775-15785. [PMID: 37850536 DOI: 10.1039/d3dt02074f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2023]
Abstract
The uptake of hydrogen atoms (H-atoms) at reducible metal oxide nanocrystal surfaces has implications in catalysis and energy storage. However, it is often difficult to gain insight into the physicochemical factors that dictate the thermodynamics and kinetics of H-atom transfer to the surface of these assemblies. Recently, our research group has demonstrated the formation of oxygen-atom (O-atom) defects in polyoxovanadate-alkoxide (POV-alkoxide) clusters via conversion of surface oxido moieties to aquo ligands, which can be accomplished via addition of two H-atom equivalents. Here, we present the dependence of O-atom defect formation via H-atom transfer at the surface of vanadium oxide clusters on the length of surface alkoxide ligands. Analysis of H-atom transfer reactions to low-valent POV-alkoxide clusters [V6O7(OR)12]1- (R = Me, Et, nPr, nBu) reveals that the length of primary alkoxide surface ligands does not significantly influence the thermodynamics of these processes. However, surface ligand length has a significant impact on the kinetics of these PCET reactions. Indeed, the methoxide-bridged cluster, [V6O7(OMe)12]1- reacts ∼20 times faster than the other derivatives evaluated. Interestingly, as the aliphatic linkages are increased in size from -C2H5 to -C4H9, reaction rates remain consistent, suggesting restricted access to available ligand conformers as a result of the incompatibility of the aliphatic ligands and acetonitrile may buffer further changes to the rate of reaction.
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Affiliation(s)
- Chari Y M Peter
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
| | - Eric Schreiber
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
| | - Kathryn R Proe
- 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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13
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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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14
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Marinho T, Schreiber E, Garwick RE, Brennessel WW, Matson EM. Manipulating Ligand Density at the Surface of Polyoxovanadate-Alkoxide Clusters. Inorg Chem 2023; 62:15616-15626. [PMID: 37712579 PMCID: PMC10523436 DOI: 10.1021/acs.inorgchem.3c02314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Indexed: 09/16/2023]
Abstract
We present the post-synthetic modification of a polyoxovanadate-alkoxide (POV-alkoxide) cluster via the reactivity of its cationic form, [V6O7(OCH3)12]1+, with water. This result indicates that cluster oxidation increases the lability of bridging methoxide ligands, affording a ligand exchange reaction that serves to compensate for the increased charge of the cluster core. This synthetic advance affords the isolation of a series of POV-alkoxide clusters with varying degrees of μ2-O2- ligands incorporated at the surface, namely, [V6O8(OCH3)11], [V6O9(OCH3)10], and [V6O10(OCH3)9]. Characterization of the POV-alkoxide clusters is described; changes in the infrared and electronic absorption spectra are consistent with the oxidation of the cluster core. We also examine the consequences of ligand substitution on the redox properties of the series of POV-alkoxide clusters via cyclic voltammetry; decreased alkoxide ligand density translates to a cathodic shift of analogous redox events. Ligand substitution also increases comproportionation constants of the Lindqvist core, indicating electron exchange between vanadium centers is promoted in structures with greater numbers of μ2-O2- ligands.
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Affiliation(s)
- Thompson
V. Marinho
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Eric Schreiber
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Rachel E. Garwick
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - William W. Brennessel
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Ellen M. Matson
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
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15
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Salazar Marcano DE, Kalandia G, Moussawi MA, Van Hecke K, Parac-Vogt TN. Rational synthesis of elusive organic-inorganic hybrid metal-oxo clusters: formation and post-functionalization of hexavanadates. Chem Sci 2023; 14:5405-5414. [PMID: 37234890 PMCID: PMC10207889 DOI: 10.1039/d3sc00038a] [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: 01/03/2023] [Accepted: 04/22/2023] [Indexed: 05/28/2023] Open
Abstract
Paving the way towards new functional materials relies increasingly on the challenging task of forming organic-inorganic hybrid compounds. In that regard, discrete atomically-precise metal-oxo nanoclusters have received increasing attention due to the wide range of organic moieties that can be grafted onto them through functionalization reactions. The Lindqvist hexavanadate family of clusters, such as [V6O13{(OCH2)3C-R}2]2- (V6-R), is particularly interesting due to the magnetic, redox, and catalytic properties of these clusters. However, compared to other metal-oxo cluster types, V6-R clusters have been less extensively explored, which is mainly due to poorly understood synthetic challenges and the limited number of viable post-functionalization strategies. In this work, we present an in-depth investigation of the factors that influence the formation of hybrid hexavanadates (V6-R HPOMs) and leverage this knowledge to develop [V6O13{(OCH2)3CNHCOCH2Cl}2]2- (V6-Cl) as a new and tunable platform for the facile formation of discrete hybrid structures based on metal-oxo clusters in relatively high yields. Moreover, we showcase the versatility of the V6-Cl platform through its post-functionalization via nucleophilic substitution with various carboxylic acids of differing complexity and with functionalities that are relevant in multiple disciplines, such as supramolecular chemistry and biochemistry. Hence, V6-Cl was shown to be a straightforward and versatile starting point for the formation of functional supramolecular structures or other hybrid materials, thereby enabling their exploration in various fields.
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Affiliation(s)
| | - Givi Kalandia
- Department of Chemistry, KU Leuven Celestijnenlaan 200F 3001 Leuven Belgium
| | | | - Kristof Van Hecke
- XStruct, Department of Chemistry, Ghent University Krijgslaan 281, S-3 9000 Ghent Belgium
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16
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Falaise C, Mpacko Priso G, Leclerc N, Haouas M, Cadot E. Making Heterometallic Metal-Metal Bonds in Keggin-Type Polyoxometalates by a Six-Electron Reduction Process. Inorg Chem 2023; 62:2494-2502. [PMID: 36716738 DOI: 10.1021/acs.inorgchem.2c03769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Polyoxometalates (POMs) represent a promising class of molecular electron reservoirs. However, their multielectron reduction gives rise to intricate physical-chemical phenomena that must be fully understood for their future use in energy-storage devices. Herein, we show that bulk electrolysis of the archetypal Keggin-type POM [Si(WVI2MoVIO10)(WVI3O10)3]4- in aqueous solution leads to the six-electron-reduced derivative [Si(WIV2MoIVO7(H2O)3)(WVI3O10)3]4- (notated SiW11Mo-VI') in which the mixed-metal triad acts as a storage unit for six electrons and six protons. X-ray diffraction analysis and multinuclear NMR (183W and 95Mo) studies reveal that this electron-rich species represents the first example of POMs containing heterometallic metal-metal bonds between addenda centers. This electron-rich POM can be further reduced through multielectronic events, while its full oxidation restores the structure of the oxidized parent ion. Remarkably, the formation of SiW11Mo-VI' results from a fast clustering process compared to that observed for the entirely W-based analogue, revealing that the formation of metal-metal bonds in the mixed-metal Mo/W POM is facilitated because the reaction rate is not limited by a slow disproportionation step. Last, we evaluate the supramolecular properties of SiW11Mo-VI' using a method based on the cloud-point measurement of a nonionic surfactant. This investigation demonstrates that the clustering process has dramatic consequences on the solution behavior of the POM, canceling its superchaotropic character due to a local structuring effect of the hydration shell. These fundamental results pave the way for applications using the massive electron-storage properties of mixed-metal POMs.
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Affiliation(s)
- Clément Falaise
- Institut Lavoisier de Versailles, CNRS, UVSQ, Université Paris-Saclay, 45 avenue des Etats-Unis, 78035Versailles, France
| | - Gabrielle Mpacko Priso
- Institut Lavoisier de Versailles, CNRS, UVSQ, Université Paris-Saclay, 45 avenue des Etats-Unis, 78035Versailles, France
| | - Nathalie Leclerc
- Institut Lavoisier de Versailles, CNRS, UVSQ, Université Paris-Saclay, 45 avenue des Etats-Unis, 78035Versailles, France
| | - Mohamed Haouas
- Institut Lavoisier de Versailles, CNRS, UVSQ, Université Paris-Saclay, 45 avenue des Etats-Unis, 78035Versailles, France
| | - Emmanuel Cadot
- Institut Lavoisier de Versailles, CNRS, UVSQ, Université Paris-Saclay, 45 avenue des Etats-Unis, 78035Versailles, France
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17
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Schreiber E, Brennessel WW, Matson EM. Regioselectivity of concerted proton-electron transfer at the surface of a polyoxovanadate cluster. Chem Sci 2023; 14:1386-1396. [PMID: 36794190 PMCID: PMC9906639 DOI: 10.1039/d2sc05928b] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 12/19/2022] [Indexed: 01/19/2023] Open
Abstract
Proton-coupled electron transfer (PCET) is an important process in the activation and reactivity of metal oxide surfaces. In this work, we study the electronic structure of a reduced polyoxovanadate-alkoxide cluster bearing a single bridging oxide moiety. The structural and electronic implications of the incorporation of bridging oxide sites are revealed, most notably resulting in the quenching of cluster-wide electron delocalization in the most reduced state of the molecule. We correlate this attribute to a change in regioselectivity of PCET to the cluster surface (e.g. reactivity at terminal vs. bridging oxide groups). Reactivity localized at the bridging oxide site enables reversible storage of a single H-atom equivalent, changing the stoichiometry of PCET from a 2e-/2H+ process. Kinetic investigations indicate that the change in site of reactivity translates to an accelerated rate of e-/H+ transfer to the cluster surface. Our work summarizes the role which electronic occupancy and ligand density play in the uptake of e-/H+ pairs at metal oxide surfaces, providing design criteria for functional materials for energy storage and conversion processes.
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Affiliation(s)
- Eric Schreiber
- Department of Chemistry, University of Rochester Rochester NY 14611 USA
| | | | - Ellen M Matson
- Department of Chemistry, University of Rochester Rochester NY 14611 USA
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18
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K/Bidi L, Desjonquères A, Izzet G, Guillemot G. H 2 Evolution at a Reduced Hybrid Polyoxometalate and Its Vanadium-Oxo Derivative Used as Molecular Models for Reducible Metal Oxides. Inorg Chem 2023; 62:1935-1941. [PMID: 35912483 DOI: 10.1021/acs.inorgchem.2c01741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We herein report our investigations on the use of a tris-silanol-decorated polyoxotungstate, [SbW9O33(tBuSiOH)3]3-, as a molecular support model to describe the coordination of an isolated vanadium atom at metal oxides, focusing on the reactivity of the reduced derivatives in the presence of protons. Accumulation of electrons and protons at an active site is a main feature associated with heterogeneous catalysts able to conduct the (oxy)dehydrogenation of alkanes or alcohols. Our results indicate that two-electron reduced derivatives release H2 upon protonation, a reaction that probably takes place at the polyoxotungstic framework rather than at the vanadium center.
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Affiliation(s)
- Ludivine K/Bidi
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, F-75005 Paris, France
| | - Alix Desjonquères
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, F-75005 Paris, France
| | - Guillaume Izzet
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, F-75005 Paris, France
| | - Geoffroy Guillemot
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, F-75005 Paris, France
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19
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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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20
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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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21
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Li N, Yue CY, Yang H, Song J, Li JW, Pan QL, Jiang S, Zhao JG, Yu D. Oxidative desulfurization and magnetic properties of a mixed-valence cobalt vanadate. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.116077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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22
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Gómez-Torres A, Mavragani N, Metta-Magaña A, Murugesu M, Fortier S. Molecular Capacitors: Accessible 6- and 8-Electron Redox Chemistry from Dimeric "Ti(I)" and "Ti(0)" Synthons Supported by Imidazolin-2-Iminato Ligands. Inorg Chem 2022; 61:16856-16873. [PMID: 36219252 DOI: 10.1021/acs.inorgchem.2c02881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reduction of the diamagnetic Ti(III)/Ti(III) dimer [Cl2Ti(μ-NImDipp)]2 (1) (NImDipp = [1,3-bis(Dipp)imidazolin-2-iminato]-, Dipp = C6H3-2,6-iPr2) with 4 and 6 equiv of KC8 generates the intramolecularly arene-masked, dinuclear titanium compounds [(μ-N-η6-ImDipp)Ti]2 (2) and {[(Et2O)2K](μ-N-μ-η6:η6-ImDipp)Ti}2 (3), respectively, in modest yields. The compounds have been structurally characterized by X-ray crystallographic analysis, and inspection of the bond metrics within the η6-coordinated aryl substituent of the bridging imidazolin-2-iminato ligand shows perturbation of the aromatic system most consistent with two-electron reduction of the ring. As such, 2 and 3 can be assigned respectively as possessing metal centers in formal Ti(III)/Ti(III) and Ti(II)/Ti(II) oxidation states. Exploration of their redox chemistry reveal the ability to reduce several substrate equivalents. For instance, treatment of 2 with excess C8H8 (COT) forms the novel COT-bridged complex [(ImDippN)(η8-COT)Ti](μ-η2:η3-COT)[Ti(η4-COT)(NImDipp)] (4) that dissociates in THF solutions to give mononuclear (ImDippN)Ti(η8-COT)(THF) (5). Addition of COT to 3 yields heterometallic [(ImDippN)(η4-COT)Ti(μ-η4:η5-COT)K(THF)(μ-η6:η4-COT)Ti(NImDipp)(μ-η4:η4-COT)K(THF)2]n (6). Compounds 4 and 5 are the products of the 4-electron oxidation of 2, while 6 stands as the 8-electron oxidation product of 3. Reduction of organozides was also explored. Low temperature reaction of 2 with 4 equiv of AdN3 gives the terminal and bridged imido complex [(ImDippN)Ti(═NAd)](μ-NAd)2[Ti(NImDipp)(N3Ad)] (7) that undergoes intermolecular C-H activation of toluene at room temperature to afford the amido compound [(ImDippN)Ti(NHAd)](μ-NAd)2[Ti(C6H4Me)(NImDipp)] (8-tol). These complexes are the 6-electron oxidation products of the reaction of 2 with AdN3. Furthermore, treatment of 3 with 4 equiv of AdN3 produces the thermally stable Ti(III)/Ti(III) terminal and bridged imido [K(18-crown-6)(THF)2]{[(ImDippN)Ti(NAd)](μ-NAd)2K[Ti(NImDipp)]} (10). Altogether, these reactions firmly establish 2 and 3 as unprecedented Ti(I)/Ti(I) and Ti(0)/Ti(0) synthons with the clear capacity to effect multielectron reductions ranging from 4 to 8 electrons.
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Affiliation(s)
- Alejandra Gómez-Torres
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Niki Mavragani
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Alejandro Metta-Magaña
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
| | - Muralee Murugesu
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Skye Fortier
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States
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23
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Fertig AA, Matson EM. Connecting Thermodynamics and Kinetics of Proton Coupled Electron Transfer at Polyoxovanadate Surfaces Using the Marcus Cross Relation. Inorg Chem 2022; 62:1958-1967. [PMID: 36049052 PMCID: PMC9906739 DOI: 10.1021/acs.inorgchem.2c02541] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Here, we evaluate the efficacy of multiple methods for elucidating the average bond dissociation free energy (BDFE) of two surface hydroxide moieties in a reduced polyoxovanadate cluster, [V6O11(OH)2(TRIOLNO2)2]-2. Through cyclic voltammetry, individual thermochemical parameters describing proton coupled electron transfer (PCET) are obtained, without the need for synthetic isolation of intermediates. Further, we demonstrate that a method involving a series of open circuit potential measurements with varying ratios of reduced to oxidized clusters is most attractive for the direct measurement of BDFE(O-H) for polyoxovanadate clusters as this approach also determines the stoichiometry of PCET. We subsequently connect the driving force of PCET to the rate constant for the transfer of hydrogen atoms to a series of organic substrates through the Marcus cross relation. We show that this method is applicable for the prediction of reaction rates for multielectron/multiproton transfer reactions, extending the findings from previous work focused on single electron/proton reactions.
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24
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Fertig AA, Cooney SE, Meyer RL, Brennessel WW, Matson EM. Mechanistic insight into rapid oxygen-atom transfer from a calix-functionalized polyoxovanadate. Chem Commun (Camb) 2022; 58:6004-6007. [PMID: 35485443 DOI: 10.1039/d2cc01228f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report accelerated rates of oxygen-atom transfer from a polyoxovanadate-alkoxide cluster following functionalization with a 4-tertbutylcalix[4]arene ligand. Incorporation of this electron withdrawing ligand modifies the electronics of the metal oxide core, favoring a mechanism in which the rate of oxygen-atom transfer is limited by outer-sphere electron transfer.
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Affiliation(s)
- Alex A Fertig
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
| | - Shannon E Cooney
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
| | - Rachel L Meyer
- 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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25
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Hu B, Yang Y, Wang J, Wang W, Li J, Liu S, Xia D, Lin K, Dong Y, Fan R. Investigation on the Mechanism of Radical Intermediate Formation and Moderate Oxidation of Spiro-OMeTAD by the Synergistic Effect of Multisubstituted Polyoxometalates in Perovskite Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2022; 14:17610-17620. [PMID: 35380420 DOI: 10.1021/acsami.1c24337] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Conventional oxidation of 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD) by air would bring various drawbacks for perovskite solar cells (PSCs), such as low power conversion efficiency (PCE) and poor stability. Here, a series of heteroatom-substituted Keggin-type polyoxometalates (POMs), H4PMo11VO40 (PMo11V), H5PMo10V2O40 (PMo10V2), and H6PMo9V3O40 (PMo9V3) are prepared and applied as p-type dopants to realize quantitative and controllable oxidation of Spiro-OMeTAD under an inert condition. The possible mechanism and electron donor regions in the oxidation of Spiro-OMeTAD are investigated using two-dimensional nuclear magnetic resonance (NMR) spectra and the relationship between POM structures and the oxidation degree of Spiro-OMeTAD is proposed. In addition, the synergistic effect of heteroatoms makes V2-substituted PMo10V2 exhibit appropriate oxidation of Spiro-OMeTAD and promoted the highest efficient hole extraction as well as the decreased charge recombination. Therefore, the champion device doped with PMo10V2 shows a PCE of 20.41% and a superior open circuit voltage (Voc) of 1.133 V, surpassing that of the pristine device (18.61%). This work presents a fresh perspective to the controllable oxidation of Spiro-OMeTAD employing economical inorganic POM dopants, which would promote the commercialization of PSCs.
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Affiliation(s)
- Boyuan Hu
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Yulin Yang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Jiaqi Wang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Wei Wang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Jiao Li
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Shihui Liu
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Debin Xia
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Kaifeng Lin
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Yayu Dong
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Ruiqing Fan
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
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Schreiber E, Fertig AA, Brennessel WW, Matson EM. Oxygen-Atom Defect Formation in Polyoxovanadate Clusters via Proton-Coupled Electron Transfer. J Am Chem Soc 2022; 144:5029-5041. [PMID: 35275632 PMCID: PMC8949770 DOI: 10.1021/jacs.1c13432] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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The uptake of hydrogen
atoms (H-atoms) into reducible metal oxides
has implications in catalysis and energy storage. However, outside
of computational modeling, it is difficult to obtain insight into
the physicochemical factors that govern H-atom uptake at the atomic
level. Here, we describe oxygen-atom vacancy formation in a series
of hexavanadate assemblies via proton-coupled electron transfer, presenting
a novel pathway for the formation of defect sites at the surface of
redox-active metal oxides. Kinetic investigations reveal that H-atom
transfer to the metal oxide surface occurs through concerted proton–electron
transfer, resulting in the formation of a transient VIII–OH2 moiety that, upon displacement of the water
ligand with an acetonitrile molecule, forms the oxygen-deficient polyoxovanadate-alkoxide
cluster. Oxidation state distribution of the cluster core dictates
the affinity of surface oxido ligands for H-atoms, mirroring the behavior
of reducible metal oxide nanocrystals. Ultimately, atomistic insights
from this work provide new design criteria for predictive proton-coupled
electron-transfer reactivity of terminal M=O moieties at the
surface of nanoscopic metal oxides.
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Affiliation(s)
- Eric Schreiber
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Alex A Fertig
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - William W Brennessel
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Ellen M Matson
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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