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Muckerman JT, Kowalczyk M, Badiei YM, Polyansky DE, Concepcion JJ, Zong R, Thummel RP, Fujita E. New water oxidation chemistry of a seven-coordinate ruthenium complex with a tetradentate polypyridyl ligand. Inorg Chem 2014; 53:6904-13. [PMID: 24911180 DOI: 10.1021/ic500709h] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The mononuclear ruthenium(II) complex [Ru](2+) (Ru = Ru(dpp)(pic)2, where dpp is the tetradentate 2,9-dipyrid-2'-yl-1,10-phenanthroline ligand and pic is 4-picoline) reported by Thummel's group (Inorg. Chem. 2008, 47, 1835-1848) that contains no water molecule in its primary coordination shell is evaluated as a catalyst for water oxidation in artificial photosynthesis. A detailed theoretical characterization of the energetics, thermochemistry, and spectroscopic properties of intermediates allowed us to interpret new electrochemical and spectroscopic experimental data, and propose a mechanism for the water oxidation process that involves an unprecedented sequence of seven-coordinate ruthenium complexes as intermediates. This analysis provides insights into a mechanism that generates four electrons and four protons in the solution and a gas-phase oxygen molecule at different pH values. On the basis of the calculations and corroborated substantially by experiments, the catalytic cycle goes through [(2)Ru(III)](3+) and [(2)Ru(V)(O)](3+) to [(1)Ru(IV)(OOH)](3+) then [(2)Ru(III)(···(3)O2)](3+) at pH 0, and through [(3)Ru(IV)(O)](2+), [(2)Ru(V)(O)](3+), and [(1)Ru(IV)(OO)](2+) at pH 9 before reaching the same [(2)Ru(III)(···(3)O2)](3+) species, from which the liberation of the weakly bound O2 might require an additional oxidation to form [(3)Ru(IV)(O)](2+) to initiate further cycles involving all seven-coordinate species.
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Ashford DL, Glasson CRK, Norris MR, Concepcion JJ, Keinan S, Brennaman MK, Templeton JL, Meyer TJ. Controlling ground and excited state properties through ligand changes in ruthenium polypyridyl complexes. Inorg Chem 2014; 53:5637-46. [PMID: 24849026 DOI: 10.1021/ic500408j] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The capture and storage of solar energy requires chromophores that absorb light throughout the solar spectrum. We report here the synthesis, characterization, electrochemical, and photophysical properties of a series of Ru(II) polypyridyl complexes of the type [Ru(bpy)2(N-N)](2+) (bpy = 2,2'-bipyridine; N-N is a bidentate polypyridyl ligand). In this series, the nature of the N-N ligand was altered, either through increased conjugation or incorporation of noncoordinating heteroatoms, as a way to use ligand electronic properties to tune redox potentials, absorption spectra, emission spectra, and excited state energies and lifetimes. Electrochemical measurements show that lowering the π* orbitals on the N-N ligand results in more positive Ru(3+/2+) redox potentials and more positive first ligand-based reduction potentials. The metal-to-ligand charge transfer absorptions of all of the new complexes are mostly red-shifted compared to Ru(bpy)3(2+) (λmax = 449 nm) with the lowest energy MLCT absorption appearing at λmax = 564 nm. Emission energies decrease from λmax = 650 nm to 885 nm across the series. One-mode Franck-Condon analysis of room-temperature emission spectra are used to calculate key excited state properties, including excited state redox potentials. The impacts of ligand changes on visible light absorption, excited state reduction potentials, and Ru(3+/2+) potentials are assessed in the context of preparing low energy light absorbers for application in dye-sensitized photoelectrosynthesis cells.
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Bettis SE, Hanson K, Wang L, Gish MK, Concepcion JJ, Fang Z, Meyer TJ, Papanikolas JM. Photophysical Characterization of a Chromophore/Water Oxidation Catalyst Containing a Layer-by-Layer Assembly on Nanocrystalline TiO2 Using Ultrafast Spectroscopy. J Phys Chem A 2014; 118:10301-8. [DOI: 10.1021/jp411139j] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Schmidt RD, Kent CA, Concepcion JJ, Lin W, Meyer TJ, Forbes MDE. A little spin on the side: solvent and temperature dependent paramagnetism in [RuII(bpy)2(phendione)]2+. Dalton Trans 2014; 43:17729-39. [DOI: 10.1039/c4dt01868k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Magnetometry, 1H-NMR, EPR and substituent effects are used to explain solvent and temperature dependent paramagnetism in [RuII(bpy)2(phendione)](PF6)2.
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Chen Z, Concepcion JJ, Song N, Meyer TJ. Chloride-assisted catalytic water oxidation. Chem Commun (Camb) 2014; 50:8053-6. [DOI: 10.1039/c4cc04071f] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Nayak A, Knauf RR, Hanson K, Alibabaei L, Concepcion JJ, Ashford DL, Dempsey JL, Meyer TJ. Synthesis and photophysical characterization of porphyrin and porphyrin–Ru(ii) polypyridyl chromophore–catalyst assemblies on mesoporous metal oxides. Chem Sci 2014. [DOI: 10.1039/c4sc00875h] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Norris MR, Concepcion JJ, Fang Z, Templeton JL, Meyer TJ. Low-Overpotential Water Oxidation by a Surface-Bound Ruthenium-Chromophore-Ruthenium-Catalyst Assembly. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201305951] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Norris MR, Concepcion JJ, Fang Z, Templeton JL, Meyer TJ. Low-Overpotential Water Oxidation by a Surface-Bound Ruthenium-Chromophore-Ruthenium-Catalyst Assembly. Angew Chem Int Ed Engl 2013; 52:13580-3. [DOI: 10.1002/anie.201305951] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 10/09/2013] [Indexed: 11/06/2022]
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Norris MR, Concepcion JJ, Glasson CRK, Fang Z, Lapides AM, Ashford DL, Templeton JL, Meyer TJ. Synthesis of Phosphonic Acid Derivatized Bipyridine Ligands and Their Ruthenium Complexes. Inorg Chem 2013; 52:12492-501. [DOI: 10.1021/ic4014976] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Concepcion JJ, Binstead RA, Alibabaei L, Meyer TJ. Application of the Rotating Ring-Disc-Electrode Technique to Water Oxidation by Surface-Bound Molecular Catalysts. Inorg Chem 2013; 52:10744-6. [DOI: 10.1021/ic402240t] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hewitt JT, Concepcion JJ, Damrauer NH. Inverse Kinetic Isotope Effect in the Excited-State Relaxation of a Ru(II)–Aquo Complex: Revealing the Impact of Hydrogen-Bond Dynamics on Nonradiative Decay. J Am Chem Soc 2013; 135:12500-3. [DOI: 10.1021/ja4037498] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Song W, Ito A, Binstead RA, Hanson K, Luo H, Brennaman MK, Concepcion JJ, Meyer TJ. Accumulation of multiple oxidative equivalents at a single site by cross-surface electron transfer on TiO2. J Am Chem Soc 2013; 135:11587-94. [PMID: 23848562 DOI: 10.1021/ja4032538] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The photodriven accumulation of two oxidative equivalents at a single site was investigated on TiO2 coloaded with a ruthenium polypyridyl chromophore [Ru(bpy)2((4,4'-(OH)2PO)2bpy)](2+) (Ru(II)P(2+), bpy = 2,2'-bipyridine, ((OH)2PO)2-bpy = 2,2'-bipyridine-4,4'-diyldiphosphonic acid) and a water oxidation catalyst [Ru(Mebimpy) ((4,4'-(OH)2PO-CH2)2bpy)(OH2)](2+) (Ru(II)OH2(2+), Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine, (4,4'-(OH)2PO-CH2)2bpy) = 4,4'-bis-methlylenephosphonato-2,2'-bipyridine). Electron injection from the metal-to-ligand charge transfer (MLCT) excited state of -Ru(II)P(2+) (-Ru(II)P(2+)*) to give -Ru(III)P(3+) and TiO2(e(-)) was followed by rapid (<20 ns) nearest-neighbor -Ru(II)OH2(2+) to -Ru(III)P(3+) electron transfer. On surfaces containing both -Ru(II)P(2+) and -Ru(III)OH2(3+) (or -Ru(III)OH(2+)), -Ru(II)OH2(2+) was formed by random migration of the injected electron inside the TiO2 nanoparticle and recombination with the preoxidized catalyst, followed by relatively slow (μs-ms) non-nearest neighbor cross-surface electron transfer from -Ru(II)OH2(2+) to -Ru(III)P(3+). Steady state illumination of coloaded TiO2 photoanodes in a dye sensitized photoelectrosynthesis cell (DSPEC) configuration resulted in the buildup of -Ru(III)P(3+), -Ru(III)OH(2+), and -Ru(IV)═O(2+), with -Ru(IV)═O(2+) formation favored at high chromophore to catalyst ratios.
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Méndez MA, Alibabaei L, Concepcion JJ, Meyer TJ. Electrocatalysis on Oxide-Stabilized, High-Surface Area Carbon Electrodes. ACS Catal 2013. [DOI: 10.1021/cs4003595] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Kent CA, Concepcion JJ, Dares CJ, Torelli DA, Rieth AJ, Miller AS, Hoertz PG, Meyer TJ. Water Oxidation and Oxygen Monitoring by Cobalt-Modified Fluorine-Doped Tin Oxide Electrodes. J Am Chem Soc 2013; 135:8432-5. [DOI: 10.1021/ja400616a] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Harrison DP, Lapides AM, Binstead RA, Concepcion JJ, Méndez MA, Torelli DA, Templeton JL, Meyer TJ. Coordination Chemistry of Single-Site Catalyst Precursors in Reductively Electropolymerized Vinylbipyridine Films. Inorg Chem 2013; 52:4747-9. [DOI: 10.1021/ic302472r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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41
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Norris MR, Concepcion JJ, Harrison DP, Binstead RA, Ashford DL, Fang Z, Templeton JL, Meyer TJ. Redox Mediator Effect on Water Oxidation in a Ruthenium-Based Chromophore–Catalyst Assembly. J Am Chem Soc 2013; 135:2080-3. [DOI: 10.1021/ja311645d] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Moonshiram D, Purohit V, Concepcion JJ, Meyer TJ, Pushkar Y. Mechanism of Catalytic Water Oxidation by the Ruthenium Blue Dimer Catalyst: Comparative Study in D₂O versus H₂O. MATERIALS 2013; 6:392-409. [PMID: 28809314 PMCID: PMC5452097 DOI: 10.3390/ma6020392] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/05/2013] [Accepted: 01/23/2013] [Indexed: 12/30/2022]
Abstract
Water oxidation is critically important for the development of energy solutions based on the concept of artificial photosynthesis. In order to gain deeper insight into the mechanism of water oxidation, the catalytic cycle for the first designed water oxidation catalyst, cis,cis-[(bpy)2(H2O)RuIIIORuIII(OH2)(bpy)2]4+ (bpy is 2,2-bipyridine) known as the blue dimer (BD), is monitored in D2O by combined application of stopped flow UV-Vis, electron paramagnetic resonance (EPR) and resonance Raman spectroscopy on freeze quenched samples. The results of these studies show that the rate of formation of BD[4,5] by Ce(IV) oxidation of BD[3,4] (numbers in square bracket denote oxidation states of the ruthenium (Ru) centers) in 0.1 M HNO3, as well as further oxidation of BD[4,5] are slower in D2O by 2.1–2.5. Ce(IV) oxidation of BD[4,5] and reaction with H2O result in formation of an intermediate, BD[3,4]′, which builds up in reaction mixtures on the minute time scale. Combined results under the conditions of these experiments at pH 1 indicate that oxidation of BD[3,4]′ is a rate limiting step in water oxidation with the BD catalyst.
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Hanson K, Torelli DA, Vannucci AK, Brennaman MK, Luo H, Alibabaei L, Song W, Ashford DL, Norris MR, Glasson CRK, Concepcion JJ, Meyer TJ. Self-Assembled Bilayer Films of Ruthenium(II)/Polypyridyl Complexes through Layer-by-Layer Deposition on Nanostructured Metal Oxides. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201206882] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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44
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Hanson K, Torelli DA, Vannucci AK, Brennaman MK, Luo H, Alibabaei L, Song W, Ashford DL, Norris MR, Glasson CRK, Concepcion JJ, Meyer TJ. Self-Assembled Bilayer Films of Ruthenium(II)/Polypyridyl Complexes through Layer-by-Layer Deposition on Nanostructured Metal Oxides. Angew Chem Int Ed Engl 2012; 51:12782-5. [DOI: 10.1002/anie.201206882] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Indexed: 11/09/2022]
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Ashford DL, Song W, Concepcion JJ, Glasson CRK, Brennaman MK, Norris MR, Fang Z, Templeton JL, Meyer TJ. Photoinduced electron transfer in a chromophore-catalyst assembly anchored to TiO2. J Am Chem Soc 2012; 134:19189-98. [PMID: 23101955 DOI: 10.1021/ja3084362] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Photoinduced formation, separation, and buildup of multiple redox equivalents are an integral part of cycles for producing solar fuels in dye-sensitized photoelectrosynthesis cells (DSPECs). Excitation wavelength-dependent electron injection, intra-assembly electron transfer, and pH-dependent back electron transfer on TiO(2) were investigated for the molecular assembly [((PO(3)H(2)-CH(2))-bpy)(2)Ru(a)(bpy-NH-CO-trpy)Ru(b)(bpy)(OH(2))](4+) ([TiO(2)-Ru(a)(II)-Ru(b)(II)-OH(2)](4+); ((PO(3)H(2)-CH(2))(2)-bpy = ([2,2'-bipyridine]-4,4'-diylbis(methylene))diphosphonic acid); bpy-ph-NH-CO-trpy = 4-([2,2':6',2″-terpyridin]-4'-yl)-N-((4'-methyl-[2,2'-bipyridin]-4-yl)methyl) benzamide); bpy = 2,2'-bipyridine). This assembly combines a light-harvesting chromophore and a water oxidation catalyst linked by a synthetically flexible saturated bridge designed to enable long-lived charge-separated states. Following excitation of the chromophore, rapid electron injection into TiO(2) and intra-assembly electron transfer occur on the subnanosecond time scale followed by microsecond-millisecond back electron transfer from the semiconductor to the oxidized catalyst, [TiO(2)(e(-))-Ru(a)(II)-Ru(b)(III)-OH(2)](4+)→[TiO(2)-Ru(a)(II)-Ru(b)(II)-OH(2)](4+).
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Hanson K, Ashford DL, Concepcion JJ, Binstead RA, Habibi S, Luo H, Glasson CRK, Templeton JL, Meyer TJ. Sensitized Photodecomposition of Organic Bisphosphonates By Singlet Oxygen. J Am Chem Soc 2012; 134:16975-8. [DOI: 10.1021/ja307987g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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47
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Glasson CRK, Song W, Ashford DL, Vannucci A, Chen Z, Concepcion JJ, Holland PL, Meyer TJ. Self-Assembled Bilayers on Indium–Tin Oxide (SAB-ITO) Electrodes: A Design for Chromophore–Catalyst Photoanodes. Inorg Chem 2012; 51:8637-9. [DOI: 10.1021/ic300636w] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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48
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Song W, Chen Z, Glasson CRK, Hanson K, Luo H, Norris MR, Ashford DL, Concepcion JJ, Brennaman MK, Meyer TJ. Interfacial dynamics and solar fuel formation in dye-sensitized photoelectrosynthesis cells. Chemphyschem 2012; 13:2882-90. [PMID: 22715164 DOI: 10.1002/cphc.201200100] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2012] [Revised: 05/04/2012] [Indexed: 11/12/2022]
Abstract
Dye-sensitized photoelectrosynthesis cells (DSPECs) represent a promising approach to solar fuels with solar-energy storage in chemical bonds. The targets are water splitting and carbon dioxide reduction by water to CO, other oxygenates, or hydrocarbons. DSPECs are based on dye-sensitized solar cells (DSSCs) but with photoexcitation driving physically separated solar fuel half reactions. A systematic basis for DSPECs is available based on a modular approach with light absorption/excited-state electron injection, and catalyst activation assembled in integrated structures. Progress has been made on catalysts for water oxidation and CO(2) reduction, dynamics of electron injection, back electron transfer, and photostability under conditions appropriate for water splitting. With added reductive scavengers, as surrogates for water oxidation, DSPECs have been investigated for hydrogen generation based on transient absorption and photocurrent measurements. Detailed insights are emerging which define kinetic and thermodynamic requirements for the individual processes underlying DSPEC performance.
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Ashford DL, Stewart DJ, Glasson CR, Binstead RA, Harrison DP, Norris MR, Concepcion JJ, Fang Z, Templeton JL, Meyer TJ. An Amide-Linked Chromophore–Catalyst Assembly for Water Oxidation. Inorg Chem 2012; 51:6428-30. [DOI: 10.1021/ic300061u] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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50
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Vannucci AK, Chen Z, Concepcion JJ, Meyer TJ. Nonaqueous Electrocatalytic Oxidation of the Alkylaromatic Ethylbenzene by a Surface Bound RuV(O) Catalyst. ACS Catal 2012. [DOI: 10.1021/cs300040m] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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