1
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Barakat M, Elhajj S, Yazji R, Miller AJM, Hasanayn F. Kinetic Isotope Effects and the Mechanism of CO 2 Insertion into the Metal-Hydride Bond of fac-(bpy)Re(CO) 3H. Inorg Chem 2024; 63:12133-12145. [PMID: 38901030 DOI: 10.1021/acs.inorgchem.4c01246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
The 1,2-insertion reaction of CO2 into metal-hydride bonds of d6-octahedral complexes to give κ1-O-metal-formate products is the key step in various CO2 reduction schemes and as a result has attracted extensive mechanistic investigations. For many octahedral catalysts, CO2 insertion follows an associative mechanism in which CO2 interacts directly with the coordinated hydride ligand instead of the more classical dissociative mechanism that opens an empty coordination site to bind the substrate to the metal prior to a hydride migration step. To better understand the associative mechanism, we conducted a systematic quantum chemical investigation on the reaction between CO2 and fac-(bpy)Re(CO)3H (1-Re-H; bpy = 2,2'-bipyridine) starting with the gas phase and then moving to THF and other solvents with increased dielectric constants. Detailed analyses of the potential energy surfaces (PESs) and intrinsic reaction coordinates (IRCs) reveal that the reaction is enabled in all media by an initial stage of making a 3c-2e bond between the carbon of CO2 and the metal-hydride bond that is most consistent with an organometallic bridging hydride Re-H-CO2 species. Once CO2 is bent and anchored to the metal-hydride bond, the reaction proceeds by a rotation motion via a cyclic transition state TS2 that interchanges Re-H-CO2 and Re-O-CHO coordination. The combined stages provide an asynchronous-concerted pathway for CO2 insertion on the Gibbs free energy surface with TS2 as the highest energy point. Consideration of TS2 as a rate-determining TS gives activation barriers, inverse KIEs, substituent effects, and solvent effects that agree with the experimental data available in this system. An important new insight revealed by the analyses of the results is that the initial stage of the reaction is not a hydride transfer step as has been assumed in some studies. In fact, the loose vibration of the TS that can be identified for the first stage of the reaction in solution (TS1) does not involve the Re-H stretching vibrational mode. Accordingly, the imaginary frequency of TS1 is insensitive to deuteration, and therefore, TS1 leads to no significant KIE.
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Affiliation(s)
- Mariam Barakat
- Department of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon
| | - Sarah Elhajj
- Department of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon
| | - Riyad Yazji
- Department of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Faraj Hasanayn
- Department of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon
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2
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Zhang H, Liang Q, Xie K. How to rationally design homogeneous catalysts for efficient CO 2 electroreduction? iScience 2024; 27:108973. [PMID: 38327791 PMCID: PMC10847752 DOI: 10.1016/j.isci.2024.108973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024] Open
Abstract
Electrified converting CO2 into valuable fuels and chemicals using a homogeneous electrochemical CO2 reduction (CO2ER) approach simplifies the operation, providing a potential option for decoupling energy harvesting and renewable chemical production. These merits benefit the scenarios where decentralization and intermittent power are key factors. This perspective aims to provide an overview of recent progress in homogeneous CO2ER. We introduce firstly the fundamentals chemistry of the homogeneous CO2ER, followed by a summary of the crucial factors and the important criteria broadly employed for evaluating the performance. We then highlight the recent advances in the most widely explored transition-metal coordinate complexes for the C1 and multicarbon (C2+) products from homogeneous CO2ER. Finally, we summarize the remaining challenges and opportunities for developing homogeneous electrocatalysts for efficient CO2ER. This perspective is expected to favor the rational design of efficient homogeneous electrocatalysts for selective CO2ER toward renewable fuels and feedstocks.
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Affiliation(s)
- Hui Zhang
- International Center for Quantum and Molecular Structures, College of Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Qinghua Liang
- Key Laboratory of Rare Earths, Chinese Academy of Sciences, Ganzhou, Jiangxi 341000, P.R. China
- Ganjiang Innovation Academy, Chinese Academy of Sciences, Ganzhou, Jiangxi 341000, P.R. China
| | - Ke Xie
- Department of Chemistry, Northwestern Universiy, Evanston, IL 60208, USA
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3
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Carr CR, Vrionides MA, Grills DC. Reactivity of radiolytically and photochemically generated tertiary amine radicals towards a CO2 reduction catalyst. J Chem Phys 2023; 159:244503. [PMID: 38146832 DOI: 10.1063/5.0180065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 10/30/2023] [Indexed: 12/27/2023] Open
Abstract
Homogeneous solar fuels photocatalytic systems often require several additives in solution with the catalyst to operate, such as a photosensitizer (PS), Brønsted acid/base, and a sacrificial electron donor (SED). Tertiary amines, in particular triethylamine (TEA) and triethanolamine (TEOA), are ubiquitously deployed in photocatalysis applications as SEDs and are capable of reductively quenching the PS's excited state. Upon oxidation, TEA and TEOA form TEA•+ and TEOA•+ radical cations, respectively, which decay by proton transfer to generate redox non-innocent transient radicals, TEA• and TEOA•, respectively, with redox potentials that allow them to participate in an additional electron transfer step, thus resulting in net one-photon/two-electron donation. However, the properties of the TEA• and TEOA• radicals are not well understood, including their reducing powers and kinetics of electron transfer to catalysts. Herein, we have used both pulse radiolysis and laser flash photolysis to generate TEA• and TEOA• radicals in CH3CN, and combined with UV/Vis transient absorption and time-resolved mid-infrared spectroscopies, we have probed the kinetics of reduction of the well-established CO2 reduction photocatalyst, fac-ReCl(bpy)(CO)3 (bpy = 2,2'-bipyridine), by these radicals [kTEA• = (4.4 ± 0.3) × 109 M-1 s-1 and kTEOA• = (9.3 ± 0.6) × 107 M-1 s-1]. The ∼50× smaller rate constant for TEOA• indicates, that in contrast to a previous assumption, TEA• is a more potent reductant than TEOA• (by ∼0.2 V, as estimated using the Marcus cross relation). This knowledge will aid in the design of photocatalytic systems involving SEDs. We also show that TEA can be a useful radiolytic solvent radical scavenger for pulse radiolysis experiments in CH3CN, effectively converting unwanted oxidizing radicals into useful reducing equivalents in the form of TEA• radicals.
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Affiliation(s)
- Cody R Carr
- Chemistry Division, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA
| | - Michael A Vrionides
- Chemistry Division, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA
| | - David C Grills
- Chemistry Division, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, USA
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4
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Saha S, Doughty T, Banerjee D, Patel SK, Mallick D, Iyer ESS, Roy S, Mitra R. Electrocatalytic reduction of CO 2 to CO by a series of organometallic Re(I)-tpy complexes. Dalton Trans 2023; 52:15394-15411. [PMID: 37203345 DOI: 10.1039/d3dt00441d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A series of organometallic Re(I)(L)(CO)3Br complexes with 4'-substituted terpyridine ligands (L) has been synthesised as electrocatalysts for CO2 reduction. The complexes' spectroscopic characterisation and computationally optimised geometry demonstrate a facial geometry around Re(I) with three cis COs and the terpyridine ligand coordinating in a bidentate mode. The effect of substitution on the 4'-position of terpyridine (Re1-5) on CO2 electroreduction was investigated and compared with a known Lehn-type catalyst, Re(I)(bpy)(CO)3Br (Re7). All complexes catalyse CO evolution in homogeneous organic media at moderate overpotentials (0.75-0.95 V) with faradaic yields of 62-98%. The electrochemical catalytic activity was further evaluated in the presence of three Brønsted acids to demonstrate the influence of the pKa of the proton sources. The TDDFT and ultrafast transient absorption spectroscopy (TAS) studies showed combined charge transfer bands of ILCT and MLCT. Amongst the series, the Re-complex containing a ferrocenyl-substituted terpyridine ligand (Re5) shows an additional intra-ligand charge transfer band and was probed using UV-Vis spectroelectrochemistry.
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Affiliation(s)
- Shriya Saha
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa 403401, India.
| | - Thomas Doughty
- School of Chemistry, University of Lincoln, Green Lane, Lincoln, Lincolnshire, LN6 7DL, UK.
| | - Dibyendu Banerjee
- Department of Chemistry, Presidency University, Kolkata 700073, India.
| | - Sunil K Patel
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa 403401, India.
| | - Dibyendu Mallick
- Department of Chemistry, Presidency University, Kolkata 700073, India.
| | - E Siva Subramaniam Iyer
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa 403401, India.
| | - Souvik Roy
- School of Chemistry, University of Lincoln, Green Lane, Lincoln, Lincolnshire, LN6 7DL, UK.
| | - Raja Mitra
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Farmagudi, Goa 403401, India.
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5
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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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6
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Isopi J, Quartapelle Procopio E, Veronese L, Malferrari M, Valenti G, Panigati M, Paolucci F, Marcaccio M. Electrochemical Characterization and CO 2 Reduction Reaction of a Family of Pyridazine-Bridged Dinuclear Mn(I) Carbonyl Complexes. Molecules 2023; 28:molecules28031138. [PMID: 36770804 PMCID: PMC9922005 DOI: 10.3390/molecules28031138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 01/26/2023] Open
Abstract
Three recently synthesized neutral dinuclear carbonyl manganese complexes with the pyridazine bridging ligand, of general formula [Mn2(μ-ER)2(CO)6(μ-pydz)] (pydz = pyridazine; E = O or S; R = methyl or phenyl), have been investigated by cyclic voltammetry in dimethylformamide and acetonitrile both under an inert argon atmosphere and in the presence of carbon dioxide. This family of Mn(I) compounds behaves interestingly at negative potentials in the presence of CO2. Based on this behavior, which is herein discussed, a rather efficient catalytic mechanism for the CO2 reduction reaction toward the generation of CO has been hypothesized.
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Affiliation(s)
- Jacopo Isopi
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | | | - Lorenzo Veronese
- Dipartimento di Chimica, Università di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Marco Malferrari
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Giovanni Valenti
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Monica Panigati
- Dipartimento di Chimica, Università di Milano, Via Golgi 19, 20133 Milano, Italy
- Consorzio INSTM, Via G. Giusti 9, 50121 Firenze, Italy
| | - Francesco Paolucci
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
- Correspondence: (F.P.); (M.M.)
| | - Massimo Marcaccio
- Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
- Correspondence: (F.P.); (M.M.)
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7
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Röß-Ohlenroth R, Kraft M, Bunzen H, Volkmer D. Inhibition, Binding of Organometallics, and Thermally Induced CO Release in an MFU-4-Type Metal-Organic Framework Scaffold with Open Bidentate Bibenzimidazole Coordination Sites. Inorg Chem 2022; 61:16380-16389. [PMID: 36197843 DOI: 10.1021/acs.inorgchem.2c02394] [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
Triazolate-based MFU-4-type metal-organic frameworks are promising candidates for various applications, of which heterogeneous catalysis has emerged as a hot topic owing to the facile post-synthetic metal and ligand exchange in Kuratowski secondary building units (SBUs). Herein, we present the largest non-interpenetrated isoreticular MFU-4-type framework CFA-19 ([Co5IICl4(H2-bibt)3]; H4-bibt = 1,1',5,5'-tetrahydro-6,6'-biimidazo[4,5-f]benzotriazole; CFA-19 = Coordination Framework Augsburg University-19) and the CFA-19-Tp derivative featuring trispyrazolylborate inhibited SBUs as a scaffold with open bibenzimidazole coordination sites at the backbone of the H4-bibt linker. The proof-of-principle incorporation of accessible MIBr(CO)3 (M = Re, Mn) sites in CFA-19-Tp was revealed by single-crystal X-ray diffraction, and a thermally induced CO release was observed for MnBr(CO)3. Deprotonation of bibenzimidazole was also achieved by the reaction with ZnEt2.
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Affiliation(s)
- Richard Röß-Ohlenroth
- Chair of Solid State and Materials Chemistry, Institute of Physics, University of Augsburg, Universitätsstr. 1, D-86159 Augsburg, Germany
| | - Maryana Kraft
- Chair of Solid State and Materials Chemistry, Institute of Physics, University of Augsburg, Universitätsstr. 1, D-86159 Augsburg, Germany
| | - Hana Bunzen
- Chair of Solid State and Materials Chemistry, Institute of Physics, University of Augsburg, Universitätsstr. 1, D-86159 Augsburg, Germany
| | - Dirk Volkmer
- Chair of Solid State and Materials Chemistry, Institute of Physics, University of Augsburg, Universitätsstr. 1, D-86159 Augsburg, Germany
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8
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Nguyen P, Dao TBN, Tran TT, Tran NAT, Nguyen TA, Phan TDL, Nguyen LP, Dang VQ, Nguyen TM, Dang NN. Electrocatalytic CO 2 Reduction by [Re(CO) 3Cl(3-(pyridin-2-yl)-5-phenyl-1,2,4-triazole)] and [Re(CO) 3Cl(3-(2-pyridyl)-1,2,4-triazole)]. ACS OMEGA 2022; 7:34089-34097. [PMID: 36188295 PMCID: PMC9520745 DOI: 10.1021/acsomega.2c03278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 09/05/2022] [Indexed: 06/16/2023]
Abstract
The exploration of novel electrocatalysts for CO2 reduction is necessary to overcome global warming and the depletion of fossil fuels. In the current study, the electrocatalytic CO2 reduction of [Re(CO)3Cl(N-N)], where N-N represents 3-(2-pyridyl)-1,2,4-triazole (Hpy), 3-(pyridin-2-yl)-5-phenyl-l,2,4-triazole (Hph), and 2,2'-bipyridine-4,4' dicarboxylic acidic (bpy-COOH) ligands, was investigated. In CO2-saturated electrolytes, cyclic voltammograms showed an enhancement of the current at the second reduction wave for all complexes. In the presence of triethanolamine (TEOA), the currents of Re(Hpy), Re(Hph), and Re(bpy-COOH) enhanced significantly by approximately 4-, 2-, and 5-fold at peak potentials of -1.60, -150, and -1.69 VAg/Ag+, respectively (in comparison to without TEOA). The reduction potential of Re(Hph) was less negative than those of Re(Hpy) and Re(COOH), which was suggested to cause its least efficiency for CO2 reduction. Chronoamperometry measurements showed the stability of the cathodic current at the second reduction wave for at least 300 s, and Re(COOH) was the most stable in the CO2-catalyzed reduction. The appearance and disappearance of the absorption band in the UV/vis spectra indicated the reaction of the catalyst with molecular CO2 and its conversion to new species, which were proposed to be Re-DMF + and Re-TEOA and were supposed to react with CO2 molecules. The CO2 molecules were claimed to be captured and inserted into the oxygen bond of Re-TEOA, resulting in the enhancement of the CO2 reduction efficiency. The results indicate a new way of using these complexes in electrocatalytic CO2 reduction.
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Affiliation(s)
- Phuong
N. Nguyen
- Institute
of Applied Materials Science, Vietnam Academy of Science and Technology
(VAST), 29TL Street, Thanh Loc Ward, District 12, Ho Chi Minh City 700000, Vietnam
- Graduate
University of Science and Technology, VAST, 18 Hoang Quoc Viet Street, Cau
Giay, Ha Noi 100000, Vietnam
| | - Thi-Bich-Ngoc Dao
- Future
Materials & Devices Lab., Institute of Fundamental and Applied
Sciences, Duy Tan University, Ho Chi Minh City 700000, Vietnam
- The
Faculty of Environmental and Chemical Engineering, Duy Tan University, Danang 550000, Vietnam
| | - Trang T. Tran
- Institute
of Applied Materials Science, Vietnam Academy of Science and Technology
(VAST), 29TL Street, Thanh Loc Ward, District 12, Ho Chi Minh City 700000, Vietnam
- Department
Materials Science and Technology, University
of Science, Ward 4, District 5, Ho Chi Minh City 700000, Vietnam
| | - Ngoc-Anh T. Tran
- Institute
of Applied Materials Science, Vietnam Academy of Science and Technology
(VAST), 29TL Street, Thanh Loc Ward, District 12, Ho Chi Minh City 700000, Vietnam
- Department
Materials Science and Technology, University
of Science, Ward 4, District 5, Ho Chi Minh City 700000, Vietnam
| | - Tu A. Nguyen
- Institute
of Applied Materials Science, Vietnam Academy of Science and Technology
(VAST), 29TL Street, Thanh Loc Ward, District 12, Ho Chi Minh City 700000, Vietnam
- Department
Materials Science and Technology, University
of Science, Ward 4, District 5, Ho Chi Minh City 700000, Vietnam
| | - Thao-Dang L. Phan
- Institute
of Applied Materials Science, Vietnam Academy of Science and Technology
(VAST), 29TL Street, Thanh Loc Ward, District 12, Ho Chi Minh City 700000, Vietnam
- Department
Materials Science and Technology, University
of Science, Ward 4, District 5, Ho Chi Minh City 700000, Vietnam
| | - Loc P. Nguyen
- Institute
of Applied Materials Science, Vietnam Academy of Science and Technology
(VAST), 29TL Street, Thanh Loc Ward, District 12, Ho Chi Minh City 700000, Vietnam
- Department
Materials Science and Technology, University
of Science, Ward 4, District 5, Ho Chi Minh City 700000, Vietnam
| | - Vinh Q. Dang
- Department
Materials Science and Technology, University
of Science, Ward 4, District 5, Ho Chi Minh City 700000, Vietnam
- Vietnam
National University, Ho Chi Minh (VNU-HCM), Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Vietnam
| | - Tuan M. Nguyen
- Institute
of Applied Materials Science, Vietnam Academy of Science and Technology
(VAST), 29TL Street, Thanh Loc Ward, District 12, Ho Chi Minh City 700000, Vietnam
- Graduate
University of Science and Technology, VAST, 18 Hoang Quoc Viet Street, Cau
Giay, Ha Noi 100000, Vietnam
| | - Nam N. Dang
- Future
Materials & Devices Lab., Institute of Fundamental and Applied
Sciences, Duy Tan University, Ho Chi Minh City 700000, Vietnam
- The
Faculty of Environmental and Chemical Engineering, Duy Tan University, Danang 550000, Vietnam
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9
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Blasczak V, McKinnon M, Suntrup L, Aminudin NA, Reed B, Groysman S, Ertem MZ, Grills DC, Rochford J. Steric and Lewis Basicity Influence of the Second Coordination Sphere on Electrocatalytic CO 2 Reduction by Manganese Bipyridyl Complexes. Inorg Chem 2022; 61:15784-15800. [PMID: 36162397 DOI: 10.1021/acs.inorgchem.2c02586] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study aims to provide a greater insight into the balance between steric (bpy vs (Ph)2bpy vs mes2bpy ligands) and Lewis basic ((Ph)2bpy vs (MeOPh)2bpy vs (MeSPh)2bpy ligands) influence on the efficiencies of the protonation-first vs reduction-first CO2 reduction mechanisms with [MnI(R2bpy)(CO)3(CH3CN)]+ precatalysts, and on their respective transition-state geometries/energies for rate-determining C-OH bond cleavage toward CO evolution. The presence of only modest steric bulk at the 6,6'-diphenyl-2,2'-bipyridyl ((Ph)2bpy) ligand has here allowed unique insight into the mechanism of catalyst activation and CO2 binding by navigating a perfect medium between the nonsterically encumbered bpy-based and the highly sterically encumbered mes2bpy-based precatalysts. Cyclic voltammetry conducted in CO2-saturated electrolyte for the (Ph)2bpy-based precatalyst [2-CH3CN]+ confirms that CO2 binding occurs at the two-electron-reduced activated catalyst [2]- in the absence of an excess proton source, in contrast to prior assumptions that all manganese catalysts require a strong acid for CO2 binding. This observation is supported by computed free energies of the parent-child reaction for [Mn-Mn]0 dimer formation, where increased steric hindrance relative to the bpy-based precatalyst correlates with favorable CO2 binding. A critical balance must be adhered to, however, as the absence of steric bulk in the bpy-based precatalyst [1-CH3CN]+ maintains a lower overpotential than [2-CH3CN]+ at the protonation-first pathway with comparable kinetic performance, whereas an ∼2-fold greater TOFmax is observed at its reduction-first pathway with an almost identical overpotential as [2-CH3CN]+. Notably, excessive steric bulk in the mes2bpy-based precatalyst [3-CH3CN]+ results in increased activation free energies of the C-OH bond cleavage transition states for both the protonation-first and the reduction-first pathways relative to both [1-CH3CN]+ and [2-CH3CN]+. In fact, [3-CH3CN]+ requires a 1 V window beyond its onset potential to reach its peak catalytic current, which is in contrast to the narrower (<0.30 V) potential response window of the remaining catalysts here studied. Voltammetry recorded under 1 atm of CO2 with 2.8 M (5%) H2O establishes [2-CH3CN]+ to have the lowest overpotential (η = 0.75 V) in the series here studied, attributed to its ability to lie "on the fence" when providing sufficient steric bulk to hinder (but not prevent) [Mn-Mn]0 dimerization, while simultaneously having a limited steric impact on the free energy of activation for the rate-determining C-OH bond cleavage transition state. While the methoxyphenyl bpy-based precatalyst [4-CH3CN]+ possesses an increased steric presence relative to [2-CH3CN]+, this is offset by its capacity to stabilize the C-OH bond cleavage transition states of both the protonation-first and the reduction-first pathways by facilitating second coordination sphere H-bonding stabilization.
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Affiliation(s)
- Vanna Blasczak
- Department of Chemistry, University of Massachusetts─Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125, United States
| | - Meaghan McKinnon
- Department of Chemistry, University of Massachusetts─Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125, United States
| | - Lisa Suntrup
- Department of Chemistry, University of Massachusetts─Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125, United States
| | - Nur Alisa Aminudin
- Department of Chemistry, University of Massachusetts─Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125, United States
| | - Blake Reed
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Stanislav Groysman
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Mehmed Z Ertem
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - David C Grills
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Jonathan Rochford
- Department of Chemistry, University of Massachusetts─Boston, 100 Morrissey Boulevard, Boston, Massachusetts 02125, United States
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10
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Holzhauer L, Liagre C, Fuhr O, Jung N, Bräse S. Scope of tetrazolo[1,5- a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof. Beilstein J Org Chem 2022; 18:1088-1099. [PMID: 36105720 PMCID: PMC9443424 DOI: 10.3762/bjoc.18.111] [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: 02/25/2022] [Accepted: 07/20/2022] [Indexed: 11/23/2022] Open
Abstract
The conversion of tetrazolo[1,5-a]quinoxalines to 1,2,3-triazoloquinoxalines and triazoloimidazoquinoxalines under typical conditions of a CuAAC reaction has been investigated. Derivatives of the novel compound class of triazoloimidazoquinoxalines (TIQ) and rhenium(I) triazoloquinoxaline complexes as well as a new TIQ rhenium complex were synthesized. As a result, a small 1,2,3-triazoloquinoxaline library was obtained and the method could be expanded towards 4-substituted tetrazoloquinoxalines. The compatibility of various aliphatic and aromatic alkynes towards the reaction was investigated and the denitrogenative annulation towards imidazoloquinoxalines could be observed as a competing reaction depending on the alkyne concentration and the substitutions at the quinoxaline.
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Affiliation(s)
- Laura Holzhauer
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Chloé Liagre
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Olaf Fuhr
- Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Nicole Jung
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Stefan Bräse
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
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11
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Scherpf T, Carr CR, Donnelly LJ, Dubrawski ZS, Gelfand BS, Piers WE. A Mesoionic Carbene-Pyridine Bidentate Ligand That Improves Stability in Electrocatalytic CO 2 Reduction by a Molecular Manganese Catalyst. Inorg Chem 2022; 61:13644-13656. [PMID: 35981323 DOI: 10.1021/acs.inorgchem.2c02689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tricarbonyl Group 7 complexes have a longstanding history as efficacious CO2 electroreduction catalysts. Typically, these complexes feature an auxiliary 2,2'-bipyridine ligand that assists in redox steps by delocalizing the electron density into the ligand orbitals. While this feature lends to an accessible redox potential for CO2 electroreduction, it also presents challenges for electrocatalysis with Mn because the electron density is removed from metal-ligand bonding orbitals. The results presented here thus introduce a mesoionic carbene (MIC) as a potent ligand platform to promote Mn-based electrocatalysis. The strong σ donation of the N,C-bidentate MIC is shown to help centralize the electron density on the Mn center while also maintaining relevant redox potentials for CO2 electroreduction. Mechanistic investigation supports catalytic turnover at two operative potentials separated by 400 mV. In the low operating potential regime at -1.54 V, Mn(0) species catalyze CO2 to CO and CO32-, which has a maximum rate of 7 ± 5 s-1 and is stable for up to 30.7 h. At higher operating potential at -1.94 V, "Mn(-1)" catalyzes CO2 to CO and H2O with faster turnovers of 200 ± 100 s-1, with the trade-off being less stability at 6.7 h. The relative stabilities of Mn complexes bearing MIC and 4,4'-di-tert-butyl-2,2'-bipyridine were compared by evaluation under the same electrolysis conditions and therefore elucidated that the MIC promotes longevity for CO evolution throughout a 5 h period.
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Affiliation(s)
- Thorsten Scherpf
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Cody R Carr
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Laurie J Donnelly
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Zachary S Dubrawski
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Benjamin S Gelfand
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Warren E Piers
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
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12
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Capulín Flores L, Paul LA, Siewert I, Havenith R, Zúñiga-Villarreal N, Otten E. Neutral Formazan Ligands Bound to the fac-(CO) 3Re(I) Fragment: Structural, Spectroscopic, and Computational Studies. Inorg Chem 2022; 61:13532-13542. [PMID: 35969867 PMCID: PMC9438031 DOI: 10.1021/acs.inorgchem.2c02168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Metal complexes with ligands that coordinate via the nitrogen atom of azo (N═N) or imino (C═N) groups are of interest due to their π-acceptor properties and redox-active nature, which leads to interesting (opto)electronic properties and reactivity. Here, we describe the synthesis and characterization of rhenium(I) tricarbonyl complexes with neutral N,N-bidentate formazans, which possess both N═N and C═N fragments within the ligand backbone (Ar1-NH-N═C(R3)-N═N-Ar5). The compounds were synthesized by reacting equimolar amounts of [ReBr(CO)5] and the corresponding neutral formazan. X-ray crystallographic and spectroscopic (IR, NMR) characterization confirmed the generation of formazan-type species with the structure fac-[ReBr(CO)3(κ2-N2,N4(Ar1-N1H-N2═C(R3)-N3═N4-Ar5))]. The formazan ligand coordinates the metal center in the 'open' form, generating a five-membered chelate ring with a pendant NH arm. The electronic absorption and emission properties of these complexes are governed by the presence of low-lying π*-orbitals on the ligand as shown by DFT calculations. The high orbital mixing between the metal and ligand results in photophysical properties that contrast to those observed in fac-[ReBr(CO)3(L,L)] species with α-diimine ligands.
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Affiliation(s)
- Liliana Capulín Flores
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.,Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Circuito Exterior, 04510 México, D.F., México
| | - Lucas A Paul
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Inke Siewert
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Remco Havenith
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Noé Zúñiga-Villarreal
- Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, Circuito Exterior, 04510 México, D.F., México
| | - Edwin Otten
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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13
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Shipp J, Parker S, Spall S, Peralta-Arriaga SL, Robertson CC, Chekulaev D, Portius P, Turega S, Buckley A, Rothman R, Weinstein JA. Photocatalytic Reduction of CO 2 to CO in Aqueous Solution under Red-Light Irradiation by a Zn-Porphyrin-Sensitized Mn(I) Catalyst. Inorg Chem 2022; 61:13281-13292. [PMID: 35960651 PMCID: PMC9446891 DOI: 10.1021/acs.inorgchem.2c00091] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
This work demonstrates photocatalytic CO2 reduction
by a noble-metal-free photosensitizer-catalyst system in aqueous solution
under red-light irradiation. A water-soluble Mn(I) tricarbonyl diimine
complex, [MnBr(4,4′-{Et2O3PCH2}2-2,2′-bipyridyl)(CO)3] (1), has been fully characterized, including single-crystal X-ray crystallography,
and shown to reduce CO2 to CO following photosensitization
by tetra(N-methyl-4-pyridyl)porphyrin Zn(II) tetrachloride
[Zn(TMPyP)]Cl4 (2) under 625 nm irradiation.
This is the first example of 2 employed as a photosensitizer
for CO2 reduction. The incorporation of −P(O)(OEt)2 groups, decoupled from the core of the catalyst by a −CH2– spacer, afforded water solubility without compromising
the electronic properties of the catalyst. The photostability of the
active Mn(I) catalyst over prolonged periods of irradiation with red
light was confirmed by 1H and 13C{1H} NMR spectroscopy. This first report on Mn(I) species as a homogeneous
photocatalyst, working in water and under red light, illustrates further
future prospects of intrinsically photounstable Mn(I) complexes as
solar-driven catalysts in an aqueous environment. A Mn(I) bipyridyl tricarbonyl complex,
where the diimine
ligand is functionalized with water-solubilizing phosphonate ester
groups, has been prepared and is shown to catalytically convert CO2 to CO in aqueous solution following photosensitization from
a water-soluble Zn(II) porphyrin under red-light irradiation.
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Affiliation(s)
- James Shipp
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Simon Parker
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Steven Spall
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | | | - Craig C Robertson
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Dimitri Chekulaev
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Peter Portius
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Simon Turega
- Department of Chemistry, Sheffield Hallam University, Sheffield S1 1WB, U.K
| | - Alastair Buckley
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, U.K
| | - Rachael Rothman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, U.K
| | - Julia A Weinstein
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
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14
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Fokin I, Kuessner KT, Siewert I. Electroreduction of Carbonyl Compounds Catalyzed by a Manganese Complex. ACS Catal 2022. [DOI: 10.1021/acscatal.2c02362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Igor Fokin
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstr. 4, 37077 Göttingen, Germany
| | - Kai-Thorben Kuessner
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstr. 4, 37077 Göttingen, Germany
| | - Inke Siewert
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstr. 4, 37077 Göttingen, Germany
- Universität Göttingen, International Center for Advanced Energy Studies, Tammannstr. 4, 37077 Göttingen, Germany
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15
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Electrochemical and Light-driven CO2 reduction by Amine-Functionalized rhenium Catalysts: A comparison between primary and tertiary amine substitutions. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.115976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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16
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Hellman AN, Intrator JA, Choate J, Velazquez DA, Marinescu SC. Primary- and secondary-sphere effects of amine substituent position on rhenium bipyridine electrocatalysts for CO2 reduction. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.115933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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17
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Fujita E, Grills DC, Manbeck GF, Polyansky DE. Understanding the Role of Inter- and Intramolecular Promoters in Electro- and Photochemical CO 2 Reduction Using Mn, Re, and Ru Catalysts. Acc Chem Res 2022; 55:616-628. [PMID: 35133133 DOI: 10.1021/acs.accounts.1c00616] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Recycling of carbon dioxide to fuels and chemicals is a promising strategy for renewable energy storage. Carbon dioxide conversion can be achieved by (i) artificial photosynthesis using photoinduced electrons; (ii) electrolysis using electricity produced by photovoltaics; and (iii) thermal CO2 hydrogenation using renewable H2. The focus of our group's research is on molecular catalysts, in particular coordination complexes of transition metals (e.g., Mn, Re, and Ru), which offer versatile platforms for mechanistic studies of photo- and electrochemical CO2 reduction. The interactions of catalytic intermediates with Lewis or Brønsted acids, hydrogen-bonding moieties, solvents, cations, etc., that function as promoters or cofactors have become increasingly important for efficient catalysis. These interactions may have dramatic effects on selectivity and rates by stabilizing intermediates or lowering transition state barriers, but they are difficult to elucidate and challenging to predict. We have been carrying out experimental and theoretical studies of CO2 reduction using molecular catalysts toward addressing mechanisms of efficient CO2 reduction systems with emphasis on those containing intramolecular (or pendent) and intermolecular (solution phase) additives. This Account describes the identification of reaction intermediates produced during CO2 reduction in the presence of triethanolamine or ionic liquids, the benefits of hydrogen-bonding interactions among intermediates or cofactors, and the complications of pendent phenolic donors/phenoxide bases under electrochemical conditions.Triethanolamine (TEOA) is a common sacrificial electron donor for photosensitizer excited state reductive quenching and has a long history of use in photocatalytic CO2 reduction. It also functions as a Brønsted base in conjunction with more potent sacrificial electron donors, such as 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH). Deprotonation of the BIH•+ cation radical promotes irreversible photoinduced electron transfer by preventing charge recombination. Despite its wide use, most research to date has not considered the broader reactions of TEOA, including its direct interaction with CO2 or its influence on catalytic intermediates. We found that in acetonitrile, TEOA captures CO2 in the form of a zwitterionic adduct without any metal catalyst. In the presence of ruthenium carbonyl catalysts bearing α-diimine ligands, it participates in metal hydride formation, accelerates hydride transfer to CO2 to form the bound formate intermediate, and assists in the dissociation of formate anion from the catalyst ( J. Am. Chem. Soc. 2020, 142, 2413-2428).Hydrogen bonding and acid/base promoters are understood to interact with key catalytic intermediates, such as the metallocarboxylate or metallocarboxylic acid during CO2 reduction. The former is a high energy species, and hydrogen-bonding or Lewis acid-stabilization are beneficial. We have found that imidazolium-based ionic liquid cations can stabilize the doubly reduced form of the [ReCl(bpy)(CO)3] (bpy = 2,2'-bipyridine) electrocatalyst through both hydrogen-bonding and π-π interactions, resulting in CO2 reduction occurring at a more positive potential with a higher catalytic current ( J. Phys. Chem. Lett. 2014, 5, 2033-2038). Hydrogen bonding interactions between Lewis basic methoxy groups in the second coordination sphere of a Mn-based catalyst and the OH group of the Mn-COOH intermediate in the presence of a Brønsted acid were also found to promote C-(OH) bond cleavage, enabling access to a low-energy protonation-first pathway for CO2 reduction ( J. Am. Chem. Soc. 2017, 139, 2604-2618).The kinetics of forming the metallocarboxylic acid can be enhanced by internal acids, and its proton-induced C-OH bond cleavage to the metallocarbonyl and H2O is often the rate-limiting step. Therefore, proton movement organized by pendent hydrogen-bonding networks may also accelerate this step. In contrast, during electrolysis, OH groups in the second coordination sphere are deprotonated to the oxyanions, which deter catalytic CO2 reduction by directly binding CO2 to form the carbonate or by making an M-O bond in competition with CO2 binding ( Inorg. Chem. 2016, 55, 4582-4594). Our results emphasize that detailed mechanistic research is critical in discovering the design principles for improved catalysts.
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Affiliation(s)
- Etsuko Fujita
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - David C. Grills
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Gerald F. Manbeck
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Dmitry E. Polyansky
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
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18
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Siewert I. Electrochemical CO 2 Reduction Catalyzed by Binuclear LRe 2(CO) 6Cl 2 and LMn 2(CO) 6Br 2 Complexes with an Internal Proton Source. Acc Chem Res 2022; 55:473-483. [PMID: 35077152 DOI: 10.1021/acs.accounts.1c00609] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of certain commodity chemicals, e.g., methanol and acetic acid, relies on CO, which is currently mainly produced by the combustion of carbon or natural gas. Photo- or electrochemical conversion of atmospheric CO2 to CO represents an attractive alternative strategy as this approach is carbon-neutral. Such photo- or electrochemically formed CO can also be used in the Fischer-Tropsch process forming liquid hydrocarbons for energy storage applications. The multiple electroreduction of CO2 is preferably coupled with proton transfer steps as this requires less energy than the single outer-sphere 1e- reduction of CO2.In 1984 and 2011, it was shown that [(Lbpy)Re(CO)3Cl] (1) and [(Lbpy)Mn(CO)3Br] (2), respectively, mediate the electrochemical 2e-/2H+ reduction of CO2 forming CO and water (Lbpy = 2,2'-bipyridine). Since proton management is crucial for catalysis, recently the impact of internal proton sources close to the axial position in such complexes has been investigated. However, binuclear complexes have been used rarely as mediators although it has been shown very early for 1 that electron management is also important: the 2e-/2H+ reduction pathway with 1 exhibits a higher reaction rate than going via the singly reduced species, though the pathway requires a higher overpotential. In this Account, we focus on recent developments of binuclear LMn2(CO)6 and LRe2(CO)6 mediators with an internal phenol group in the electroreduction of CO2. In contrast to mononuclear derivatives, for which the impact of the internal proton source on catalysis is very diverse, we always observed a higher reaction rate and for the Mn complexes also a lower overpotential with the binuclear complexes compared to the mononuclear variants. Spectroscopic, electrochemical, and computational studies on the mono- and binuclear complexes shed light on their reactivity under reductive conditions, elucidated the structure of reduced species, unraveled the kinetics for catalytically productive and unproductive (side) reactions, and allowed us to derive some hypothesis on the CO2 reduction mechanism. Finally, I emphasize that the electrohydrogenation of the polar double bonds by the binuclear complex LMn2(CO)6 with a central phenol unit is not restricted to CO2 but is also applicable to organic compounds with C═O bonds.
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Affiliation(s)
- Inke Siewert
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstr. 4, 37077 Göttingen, Germany
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19
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Alberto R, Müller P, Probst B, Spingler B, Blacque O. Polar substituents enable efficient catalysis for a class of cobalt polypyridyl hydrogen evolving catalyst. Helv Chim Acta 2022. [DOI: 10.1002/hlca.202100237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Roger Alberto
- University of Zürich Department of Chemistry Winterthurerstr. 190 CH-8057 Zürich SWITZERLAND
| | - Peter Müller
- University of Zurich Faculty of Mathematics and Science: Universitat Zurich Mathematisch-Naturwissenschaftliche Fakultat Chemistry SWITZERLAND
| | - Benjamin Probst
- University of Zurich Faculty of Mathematics and Science: Universitat Zurich Mathematisch-Naturwissenschaftliche Fakultat Chemistry SWITZERLAND
| | - Bernhard Spingler
- University of Zurich Faculty of Mathematics and Science: Universitat Zurich Mathematisch-Naturwissenschaftliche Fakultat Chemistry SWITZERLAND
| | - Olivier Blacque
- University of Zurich Faculty of Science: Universitat Zurich Mathematisch-Naturwissenschaftliche Fakultat Chemistry SWITZERLAND
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20
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Koenig JDB, Piers WE, Welch GC. Promoting photocatalytic CO2 reduction through facile electronic modification of N-annulated perylene diimide rhenium bipyridine dyads. Chem Sci 2022; 13:1049-1059. [PMID: 35211271 PMCID: PMC8790914 DOI: 10.1039/d1sc05465a] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/28/2021] [Indexed: 11/24/2022] Open
Abstract
The development of CO2 conversion catalysts has become paramount in the effort to close the carbon loop. Herein, we report the synthesis, characterization, and photocatalytic CO2 reduction performance for a series of N-annulated perylene diimide (NPDI) tethered Re(bpy) supramolecular dyads [Re(bpy-C2-NPDI-R)], where R = –H, –Br, –CN, –NO2, –OPh, –NH2, or pyrrolidine (–NR2). The optoelectronic properties of these Re(bpy-C2-NPDI-R) dyads were heavily influenced by the nature of the R-group, resulting in significant differences in photocatalytic CO2 reduction performance. Although some R-groups (i.e. –Br and –OPh) did not influence the performance of CO2 photocatalysis (relative to –H; TONco ∼60), the use of an electron-withdrawing –CN was found to completely deactivate the catalyst (TONco < 1) while the use of an electron-donating –NH2 improved CO2 photocatalysis four-fold (TONco = 234). Despite being the strongest EWG, the –NO2 derivative exhibited good photocatalytic CO2 reduction abilities (TONco = 137). Using a combination of CV and UV-vis-nIR SEC, it was elucidated that the –NO2 derivative undergoes an in situ transformation to –NH2 under reducing conditions, thereby generating a more active catalyst that would account for the unexpected activity. A photocatalytic CO2 mechanism was proposed for these Re(bpy-C2-NPDI-R) dyads (based on molecular orbital descriptions), where it is rationalized that the photoexcitation pathway, as well as the electronic driving-force for NPDI2− to Re(bpy) electron-transfer both significantly influence photocatalytic CO2 reduction. These results help provide rational design principles for the future development of related supramolecular dyads. Seven N-annulated perylene diimide tethered rhenium (2,2′-bipyridine) supramolecular dyads are evaluated as photocatalysts for the reduction for carbon dioxide, highlighting the importance of photoexcitation pathway and electronic driving-force.![]()
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Affiliation(s)
- Josh D. B. Koenig
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, T2N 1N4, Canada
| | - Warren E. Piers
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, T2N 1N4, Canada
| | - Gregory C. Welch
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, T2N 1N4, Canada
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21
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Friães S, Realista S, Gomes CSB, Martinho PN, Royo B. Click-Derived Triazoles and Triazolylidenes of Manganese for Electrocatalytic Reduction of CO 2. Molecules 2021; 26:molecules26216325. [PMID: 34770734 PMCID: PMC8588546 DOI: 10.3390/molecules26216325] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/14/2021] [Accepted: 10/16/2021] [Indexed: 11/16/2022] Open
Abstract
A series of new fac-[Mn(L)(CO)3Br] complexes where L is a bidentate chelating ligand containing mixed mesoionic triazolylidene-pyridine (MIC^py, 1), triazolylidene-triazole (MIC^trz, 2), and triazole-pyridine (trz^py, 3) ligands have been prepared and fully characterized, including the single crystal X-ray diffraction studies of 1 and 2. The abilities of 1–3 and complex fac-[Mn(MIC^MIC)(CO)3Br] (4) to catalyze the electroreduction of CO2 has been assessed for the first time. It was found that all complexes displayed a current increase under CO2 atmosphere, being 3 and 4 the most active complexes. Complex 3, bearing a N^N-based ligand exhibited a good efficiency and an excellent selectivity for reducing CO2 to CO in the presence of 1.0 M of water, at low overpotential. Interestingly, complex 4 containing the strongly electron donating di-imidazolylidene ligand exhibited comparable activity to 3, when the experiments were performed in neat acetonitrile at slightly higher overpotential (−1.86 vs. −2.14 V).
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Affiliation(s)
- Sofia Friães
- ITQB NOVA, Instituto de Tecnologia Química e Biológica António Xavier, Av. da República, 2780-157 Oeiras, Portugal; (S.F.); (S.R.)
| | - Sara Realista
- ITQB NOVA, Instituto de Tecnologia Química e Biológica António Xavier, Av. da República, 2780-157 Oeiras, Portugal; (S.F.); (S.R.)
| | - Clara S. B. Gomes
- LAQV-REQUIMTE, Department of Chemistry, Campus de Caparica, NOVA School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal;
- Associated Laboratory i4HB-Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
- UCIBIO-Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, 2829-516 Caparica, Portugal
| | - Paulo N. Martinho
- Biosystems and Integrative Sciences Institute (BioISI), Faculdade de Ciências, Campo Grande, Universidade de Lisboa, 1749-016 Lisboa, Portugal;
- Centro de Química Estrutural, Campo Grande, Faculdade de Ciências Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Beatriz Royo
- ITQB NOVA, Instituto de Tecnologia Química e Biológica António Xavier, Av. da República, 2780-157 Oeiras, Portugal; (S.F.); (S.R.)
- Correspondence:
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22
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Saund SS, Siegler MA, Thoi VS. Electrochemical Degradation of a Dicationic Rhenium Complex via Hoffman-Type Elimination. Inorg Chem 2021; 60:13011-13020. [PMID: 34492759 DOI: 10.1021/acs.inorgchem.1c01427] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Electrocatalytic reduction of carbon dioxide (CO2) by transition-metal catalysts is an attractive means for storing renewably sourced electricity in chemical bonds. Metal coordination compounds represent highly tunable platforms ideal for studying the fundamental stepwise transformations of CO2 into its reduced products. However, metal complexes can decompose upon extended electrolysis and form chemically distinct molecular species or, in some cases, catalytically active electrode deposits. Deciphering the degradative pathways is important for understanding the nature of the active catalyst and designing robust metal complexes for small-molecule activation. Herein, we present a new dicationic rhenium bipyridyl complex capable of multielectron ligand-centered reductions electrochemically. Our in-depth experimental and computational study provides mechanistic insight into an unusual reductively induced Hoffman-type elimination. We identify benzylic tertiary ammonium groups as an electrolytically susceptible moiety and propose key intermediates in the degradative pathway. This investigation highlights the complex interplay between the ligand and metal ion and will guide the future design of metal-organic catalysts.
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Affiliation(s)
- Simran S Saund
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - V Sara Thoi
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States.,Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
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23
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da Silva Freitas W, D’Epifanio A, Mecheri B. Electrocatalytic CO2 reduction on nanostructured metal-based materials: Challenges and constraints for a sustainable pathway to decarbonization. J CO2 UTIL 2021. [DOI: 10.1016/j.jcou.2021.101579] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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24
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Cao X, Cao G, Li M, Zhu X, Han J, Ge Q, Wang H. Enhanced Ethylene Formation from Carbon Dioxide Reduction through Sequential Catalysis on Au Decorated Cubic Cu
2
O Electrocatalyst. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Xuerui Cao
- Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and Engineering School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China
| | - Guangwei Cao
- Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and Engineering School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China
| | - Mei Li
- Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and Engineering School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China
| | - Xinli Zhu
- Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and Engineering School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China
| | - Jinyu Han
- Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and Engineering School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China
| | - Qingfeng Ge
- Department of Chemistry and Biochemistry Southern llinois University Carbondale IL 62901 United States
| | - Hua Wang
- Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and Engineering School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China
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25
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Gerschel P, Cordes AL, Bimmermann S, Siegmund D, Metzler‐Nolte N, Apfel U. Investigation of Cyclam Based Re‐Complexes as Potential Electrocatalysts for the CO
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Reduction Reaction. Z Anorg Allg Chem 2021. [DOI: 10.1002/zaac.202000450] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Philipp Gerschel
- Inorganic Chemistry I Ruhr-Universität Bochum Universitätsstraße 150 44801 Bochum Germany
| | - Anna L. Cordes
- Inorganic Chemistry I Ruhr-Universität Bochum Universitätsstraße 150 44801 Bochum Germany
| | - Sarah Bimmermann
- Inorganic Chemistry I Ruhr-Universität Bochum Universitätsstraße 150 44801 Bochum Germany
| | - Daniel Siegmund
- Department of Electrosynthesis Fraunhofer UMSICHT Osterfelder Straße 3 46047 Oberhausen Germany
| | - Nils Metzler‐Nolte
- Inorganic Chemistry I Ruhr-Universität Bochum Universitätsstraße 150 44801 Bochum Germany
| | - Ulf‐Peter Apfel
- Inorganic Chemistry I Ruhr-Universität Bochum Universitätsstraße 150 44801 Bochum Germany
- Department of Electrosynthesis Fraunhofer UMSICHT Osterfelder Straße 3 46047 Oberhausen Germany
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26
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Fernández-Terán RJ, Sévery L. Coordination Environment Prevents Access to Intraligand Charge-Transfer States through Remote Substitution in Rhenium(I) Terpyridinedicarbonyl Complexes. Inorg Chem 2021; 60:1325-1333. [PMID: 33301310 DOI: 10.1021/acs.inorgchem.0c02914] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Six rhenium(I) κ3N-dicarbonyl complexes with 4'-(4-substituted phenyl)terpyridine ligands were evaluated in their ground and excited states. These complexes, bearing substituents of different electron-donating strengths-from CN to NMe2-were studied by a combination of transient IR (TRIR), electrochemistry, and IR spectroelectrochemistry, as well as time-dependent density functional theory (TD-DFT). They exhibit panchromatic absorption and can act as stronger photoreductants than their tricarbonyl counterparts. The ground- and excited-state potentials, absorption maxima, and lifetimes (250-750 ps) of these complexes correlate well with the Hammett σp substituent constants, showing the systematic effect of remote substitution in the ligand framework. TRIR spectroscopy allowed us to assign the lowest singlet and triplet excited states to a metal-to-ligand charge-transfer (MLCT) character. This result contrasts our previous report on analogous κ2N-tricarbonyl complexes, where remote substitution switched the character from MLCT to intraligand charge transfer. With the help of TD-DFT calculations, we dissect the geometric and electronic effects of coordination of the third pyridine, local symmetries, and increasing conjugation length. These results give valuable insights for the design of complexes with long-lived triplet excited states and enhanced absorption throughout the visible spectrum, while showcasing the boundaries of the excited-state switching strategy via remote substitution.
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Affiliation(s)
| | - Laurent Sévery
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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27
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Martin SM, Oldacre AN, Pointer CA, Huang T, Repa GM, Fredin LA, Young ER. Proton-controlled non-exponential photoluminescence in a pyridylamidine-substituted Re(I) complex. Dalton Trans 2021; 50:7265-7276. [PMID: 33954322 DOI: 10.1039/d1dt01132d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chemical intuition and well-known design principles can typically be used to create ligand environments in transition metal complexes to deliberately tune reactivity for desired applications. However, intelligent ligand design does not always result in the expected outcomes. Herein we report the synthesis and characterization of a tricarbonyl rhenium (2,2'-bipyridine) 4-pyridylamidine, Re(4-Pam), complex with unexpected photophysical properties. Photoluminescence kinetics of Re(4-Pam) undergoes non-exponential decay, which can be deconvolved into two emission lifetimes. However, upon protonation of the amidine functionality of the 4-pyridylamidine to form Re(4-PamH), a single exponential decay is observed. To understand and rationalize these experimental observations, density functional theory (DFT) and time-dependent density functional theory (TDDFT) are employed. The symmetry or asymmetry of the protonated or deprotonated 4-pyridylamidine ligand, respectively, is the key factor in switching between one and two photoluminescence lifetimes. Specifically, rotation of the dihedral angle formed between the bipyridine and 4-Pam ligand leads to two rotamers of Re(4-Pam) with degenerate triplet- to ground-state transitions.
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Affiliation(s)
- Shea M Martin
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
| | - Amanda N Oldacre
- Department of Chemistry, St Lawrence University, Canton, New York 13617, USA
| | - Craig A Pointer
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
| | - Tao Huang
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
| | - Gil M Repa
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
| | - Lisa A Fredin
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
| | - Elizabeth R Young
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
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