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Kumar P, M B, Rasool A, Demeshko S, Bommakanti S, Mukhopadhyay N, Gupta R, Dar MA, Ghosh M. Bioinspired Diiron Complex with Proton Shuttling and Redox-Active Ligand for Electrocatalytic Hydrogen Evolution. Inorg Chem 2024. [PMID: 38985539 DOI: 10.1021/acs.inorgchem.4c01112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
A μ-oxo diiron complex, featuring the pyridine-2,6-dicarboxamide-based thiazoline-derived redox-active ligand, H2L (H2L = N2,N6-bis(4,5-dihydrothiazol-2-yl)pyridine-2,6-dicarboxamide), was synthesized and thoroughly characterized. [FeIII-(μ-O)-FeIII] showed electrocatalytic hydrogen evolution reaction activity in the presence of different organic acids of varying pKa values in dimethylformamide. Through electrochemical analysis, we found that [FeIII-(μ-O)-FeIII] is a precatalyst that undergoes concerted two-electron reduction to generate an active catalyst. Fourier transform infrared spectrum of reduced species and density functional theory (DFT) investigation indicate that the active catalyst contains a bridged hydroxo unit which serves as a local proton source for the Fe(III) hydride intermediate to release H2. We propose that in this active catalyst, the thiazolinium moiety acts as a proton-transferring group. Additionally, under sufficiently strong acidic conditions, bridged oxygen gets protonated before two-electron reduction. In the presence of exogenous acids of varying strengths, it displays electro-assisted catalytic response at a distinct applied potential. Stepwise electron-transfer and protonation reactions on the metal center and the ligand were studied through DFT to understand the thermodynamically favorable pathways. An ECEC or EECC mechanism is proposed depending on the acid strength and applied potential.
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Affiliation(s)
- Pankaj Kumar
- Department of Chemistry, Ashoka University, Sonipat, Delhi NCR, Haryana 131029, India
| | - Bharath M
- Department of Chemistry, Ashoka University, Sonipat, Delhi NCR, Haryana 131029, India
| | - Anjumun Rasool
- Department of Chemistry, Islamic University of Science and Technology, Awantipora, Jammu and Kashmir 192122, India
| | - Serhiy Demeshko
- University of Göttingen, Institute of Inorganic Chemistry, Tammannstrasse 4, Göttingen D 37077, Germany
| | - Suresh Bommakanti
- School of Chemical Sciences, National Institute of Science Education and Research Bhubaneswar, Jatni, Khurda, Odisha 752050, India
| | - Narottom Mukhopadhyay
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741246, India
| | - Rajeev Gupta
- Department of Chemistry, University of Delhi, Delhi 110007, India
| | - Manzoor Ahmad Dar
- Department of Chemistry, Islamic University of Science and Technology, Awantipora, Jammu and Kashmir 192122, India
| | - Munmun Ghosh
- Department of Chemistry, Ashoka University, Sonipat, Delhi NCR, Haryana 131029, India
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Phu PN, Barman SK, Ziller JW, Hendrich MP, Borovik AS. Synthesis, characterization and reactivity of a Mn(III)-hydroxido complex as a biomimetic model for lipoxygenase. J Inorg Biochem 2024; 259:112618. [PMID: 38986289 DOI: 10.1016/j.jinorgbio.2024.112618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 05/19/2024] [Accepted: 05/24/2024] [Indexed: 07/12/2024]
Abstract
Manganese hydroxido (Mn-OH) complexes supported by a tripodal N,N',N″-[nitrilotris(ethane-2,1-diyl)]tris(P,P-diphenylphosphinic amido) ([poat]3-) ligand have been synthesized and characterized by spectroscopic techniques including UV-vis and electron paramagnetic resonance (EPR) spectroscopies. X-ray diffraction (XRD) methods were used to confirm the solid-state molecular structures of {Na2[MnIIpoat(OH)]}2 and {Na[MnIIIpoat(OH)]}2 as clusters that are linked by the electrostatic interactions between the sodium counterions and the oxygen atom of the ligated hydroxido unit and the phosphinic (P=O) amide groups of [poat]3-. Both clusters feature two independent monoanionic fragments in which each contains a trigonal bipyramidal Mn center that is comprised of three equatorial deprotonated amide nitrogen atoms, an apical tertiary amine, and an axial hydroxido ligand. XRD analyses of {Na[MnIIIpoat(OH)]}2 also showed an intramolecular hydrogen bonding interaction between the MnIII-OH unit and P=O group of [poat]3-. Crystalline {Na[MnIIIpoat(OH)]}2 remains as clusters with Na+---O interactions in solution and is unreactive toward external substrates. However, conductivity studies indicated that [MnIIIpoat(OH)]- generated in situ is monomeric and reactivity studies found that it is capable of cleaving C-H bonds, illustrating the importance of solution-phase speciation and its direct effect on chemical reactivity. Synopsis: Manganese-hydroxido complexes were synthesized to study the influence of H-bonds in the secondary coordination sphere and their effects on the oxidative cleavage of substrates containing C-H bonds.
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Affiliation(s)
- Phan N Phu
- Department of Chemistry, University of California, Irvine, CA 92697, United States
| | - Suman K Barman
- Department of Chemistry, University of California, Irvine, CA 92697, United States; Department of Chemical Sciences, India Institute of Science Education and Research (IISER) Mohali, Manauli 140306, India
| | - Joseph W Ziller
- Department of Chemistry, University of California, Irvine, CA 92697, United States
| | - Michael P Hendrich
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, United States
| | - A S Borovik
- Department of Chemistry, University of California, Irvine, CA 92697, United States.
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Lee JL, Biswas S, Ziller JW, Bominaar EL, Hendrich MP, Borovik AS. Accessing a synthetic Fe IIIMn IV core to model biological heterobimetallic active sites. Chem Sci 2024; 15:2817-2826. [PMID: 38404374 PMCID: PMC10882444 DOI: 10.1039/d3sc04900k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 12/22/2023] [Indexed: 02/27/2024] Open
Abstract
Metalloproteins with dinuclear cores are known to bind and activate dioxygen, with a subclass of these proteins having active sites containing FeMn cofactors and activities ranging from long-range proton-coupled electron transfer (PCET) to post-translational peptide modification. While mechanistic studies propose that these metallocofactors access FeIIIMnIV intermediates, there is a dearth of related synthetic analogs. Herein, the first well-characterized synthetic FeIII-(μ-O)-MnIV complex is reported; this complex shows similar spectroscopic features as the catalytically competent FeIIIMnIV intermediate X found in Class Ic ribonucleotide reductase and demonstrates PCET function towards phenolic substrates. This complex is prepared from the oxidation of the isolable FeIII-(μ-O)-MnIII species, whose stepwise assembly is facilitated by a tripodal ligand containing phosphinic amido groups. Structural and spectroscopic studies found proton movement involving the FeIIIMnIII core, whereby the initial bridging hydroxido ligand is converted to an oxido ligand with concomitant protonation of one phosphinic amido group. This series of FeMn complexes allowed us to address factors that may dictate the preference of an active site for a heterobimetallic cofactor over one that is homobimetallic: comparisons of the redox properties of our FeMn complexes with those of the di-Fe analogs suggested that the relative thermodynamic ease of accessing an FeIIIMnIV core can play an important role in determining the metal ion composition when the key catalytic steps do not require an overly potent oxidant. Moreover, these complexes allowed us to demonstrate the effect of the hyperfine interaction from non-Fe nuclei on 57Fe Mössbauer spectra which is relevant to MnFe intermediates in proteins.
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Affiliation(s)
- Justin L Lee
- Department of Chemistry, University of California-Irvine Irvine CA 92697 USA
| | - Saborni Biswas
- Department of Chemistry, Carnegie Mellon University Pittsburgh PA 15213 USA
| | - Joseph W Ziller
- Department of Chemistry, University of California-Irvine Irvine CA 92697 USA
| | - Emile L Bominaar
- Department of Chemistry, Carnegie Mellon University Pittsburgh PA 15213 USA
| | - Michael P Hendrich
- Department of Chemistry, Carnegie Mellon University Pittsburgh PA 15213 USA
| | - A S Borovik
- Department of Chemistry, University of California-Irvine Irvine CA 92697 USA
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Hertler PR, Lewis RA, Wu G, Hayton TW. Measuring Metal-Metal Communication in a Series of Ketimide-Bridged [Fe 2] 6+ Complexes. Inorg Chem 2023; 62:11829-11836. [PMID: 37462407 DOI: 10.1021/acs.inorgchem.3c01109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
Reaction of Fe(acac)3 with 3 equiv of Li[N═C(R)Ph] (R = Ph, tBu) results in the formation of the [Fe2]6+ complexes, [Fe2(μ-N═C(R)Ph)2(N═C(R)Ph)4] (R = Ph, 1; tBu, 2), in low to moderate yields. Reaction of FeCl2 with 6 equiv of Li(N═C13H8) (HN═C13H8 = 9-fluorenone imine) results in the formation of [Li(THF)2]2[Fe(N═C13H8)4] (3) in good yield. Subsequent oxidation of 3 with ca. 0.8 equiv of I2 generates the [Fe2]6+ complex, [Fe2(μ-N═C13H8)2(N═C13H8)4] (4), along with free fluorenyl ketazine. Complexes 1, 2, and 4 were characterized by 1H NMR spectroscopy, X-ray crystallography, 57Fe Mössbauer spectroscopy, and SQUID magnetometry. The Fe-Fe distances in 1, 2, and 4 range from 2.803(7) to 2.925(1) Å, indicating that no direct Fe-Fe interaction is present in these complexes. The 57Fe Mössbauer spectra for complexes 1, 2, and 4 are all consistent with the presence of symmetry-equivalent high-spin Fe3+ centers. Finally, all three complexes exhibit a similar degree of antiferromagnetic coupling between the metal centers (J = -26 to -30 cm-1), as ascertained by SQUID magnetometry.
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Affiliation(s)
- Phoebe R Hertler
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Richard A Lewis
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Guang Wu
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Trevor W Hayton
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
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Gu YM, Yuan YY, Chen CL, Zhao SS, Sun TJ, Han Y, Liu XW, Lai Z, Wang SD. Fluorido-bridged robust metal-organic frameworks for efficient C 2H 2/CO 2 separation under moist conditions. Chem Sci 2023; 14:1472-1478. [PMID: 36794184 PMCID: PMC9906641 DOI: 10.1039/d2sc06699h] [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] [Received: 12/05/2022] [Accepted: 01/02/2023] [Indexed: 01/19/2023] Open
Abstract
The modern technology for acetylene production is inevitably accompanied by the contamination of carbon dioxide and moisture impurities. Metal-organic frameworks (MOFs), with rational configurations of fluorine as the hydrogen-bonding acceptor (HBA), exhibit excellent affinities to capture acetylene from the gas mixtures. Currently, most research studies feature anionic fluorine groups as structural pillars (e.g., SiF6 2-, TiF6 2-, NbOF5 2-), whereas in situ insertion of fluorine into metal clusters is rather challenging. Herein, we report a unique fluorine-bridged Fe-MOF, i.e., DNL-9(Fe), which is assembled by mixed-valence FeIIFeIII clusters and renewable organic ligands. The fluorine species in the coordination-saturated structure offer superior C2H2-favored adsorption sites facilitated by hydrogen bonding, with a lower C2H2 adsorption enthalpy than other reported HBA-MOFs, demonstrated by static/dynamic adsorption tests and theoretical calculations. Importantly, DNL-9(Fe) shows exceptional hydrochemical stability under aqueous, acidic, and basic conditions, and its intriguing performance for C2H2/CO2 separation was even maintained at a high relative humidity of 90%.
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Affiliation(s)
- Yi-Ming Gu
- Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China .,University of Chinese Academy of Sciences Beijing 100049 China
| | - You-You Yuan
- Core Laboratory, King Abdullah University of Science and Technology (KAUST)Thuwal23955-6900Saudi Arabia
| | - Cai-Lin Chen
- Advanced Membranes and Porous Materials Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Sheng-Sheng Zhao
- Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China
| | - Tian-Jun Sun
- Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China
| | - Yu Han
- Advanced Membranes and Porous Materials Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Xiao-Wei Liu
- Advanced Membranes and Porous Materials Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Zhiping Lai
- Advanced Membranes and Porous Materials Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia
| | - Shu-Dong Wang
- Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China
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Benkó T, Shen S, Németh M, Su J, Szamosvölgyi Á, Kovács Z, Sáfrán G, Al-Zuraiji SM, Horváth EZ, Sápi A, Kónya Z, Pap JS. BiVO4 charge transfer control by a water-insoluble iron complex for solar water oxidation. APPLIED CATALYSIS A-GENERAL 2023. [DOI: 10.1016/j.apcata.2023.119035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Hale AR, Lott ME, Peralta JE, Foguet-Albiol D, Abboud KA, Christou G. Magnetic Properties of High-Nuclearity Fe x-oxo ( x = 7, 22, 24) Clusters Analyzed by a Multipronged Experimental, Computational, and Magnetostructural Correlation Approach. Inorg Chem 2022; 61:11261-11276. [PMID: 35816698 DOI: 10.1021/acs.inorgchem.2c01371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis, structure, and magnetic properties of three related iron(III)-oxo clusters are reported, [Fe7O3(O2CPh)9(mda)3(H2O)] (1), [Fe22O14(OH)3(O2CMe)21(mda)6](ClO4)2 (2), and [Fe24O15(OH)4(OEt)(O2CMe)21(mda)7](ClO4)2 (3), where mdaH2 is N-methyldiethanolamine. 1 was prepared from the reaction of [Fe3O(O2CPh)6(H2O)3](NO3) with mdaH2 in a 1:2 ratio in MeCN, whereas 2 and 3 were prepared from the reaction of FeCl3/NaO2CMe/mdaH2 in a 2:∼13:2 ratio and FeCl3/NaO2CMe/mdaH2/pyridine in a 2:∼13:2:25 ratio, respectively, both in EtOH. The core of 1 consists of a central octahedral FeIII ion held within a nonplanar Fe6 loop by three μ3-O2- and three μ2-RO- arms from the three mda2- chelates. The cores of the cations of 2 and 3 consist of an A:B:A three-layer topology, in which a central Fe6 (2) or Fe8 (3) layer B is sandwiched between two Fe8 layers A. The A layers structurally resemble 1 with the additional Fe added at the center to retain virtual C3 symmetry. The central Fe6 layer B of 2 consists of a {Fe4(μ4-O)2(μ3-OH)2}6+ cubane with an Fe on either side attached to cubane O2- ions, whereas that of 3 has the same cubane but with an {Fe3(μ3-O)(μ-OH)} unit attached on one side and a single Fe on the other. Variable-temperature dc and ac magnetic susceptibility studies revealed dominant antiferromagnetic coupling in all complexes leading to ground-state spins of S = 5/2 for 1 and S = 0 for 2 and 3. All Fe2 pairwise exchange parameters (Jij) for 1-3 were estimated by two independent methods: density functional theory (DFT) calculations using broken symmetry methods and a magnetostructural correlation previously developed for high-nuclearity FeIII/O complexes. The two approaches gave satisfyingly similar Jij values, and the latter allowed rationalization of the experimental ground states by identification of the spin frustration effects operative and the resultant relative spin vector alignments at each FeIII ion.
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Affiliation(s)
- Ashlyn R Hale
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, Unites States
| | - Megan E Lott
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, Unites States
| | - Juan E Peralta
- Department of Physics and Science of Advanced Materials, Central Michigan University, Mount Pleasant, Michigan 48859, United States
| | - Dolos Foguet-Albiol
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, Unites States
| | - Khalil A Abboud
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, Unites States
| | - George Christou
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, Unites States
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