1
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Salem YA, Elsabour SA, El-Masry AA. Validated chromatographic approach for determination of two ternary mixtures in newly approved formulations for helicobacter pylori eradication: assessment of greenness profile and content uniformity. BMC Chem 2024; 18:111. [PMID: 38863068 PMCID: PMC11167897 DOI: 10.1186/s13065-024-01215-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Accepted: 05/21/2024] [Indexed: 06/13/2024] Open
Abstract
A new, sensitive, and rapid isocratic reversed phase chromatographic method (RP-HPLC-UV) was developed for simultaneous separation of two newly co-formulated antiulcer mixtures; Amoxicillin, Vonoprazan and Clarithromycin [Mixture (I)], and Amoxicillin, Lansoprazole and Clarithromycin [Mixture (II)]. Analytical separation was performed using a Promosil C18 column and ultraviolet detection at 210 nm. The separation was achieved within only 8 min. For both mixtures, an aqueous solution, composed of (Acetonitrile: Methanol: 0. 2 M phosphoric acid) within ratio of (30: 30: 40) adjusted to final pH 3.0, was the mobile phase. This method was validated as per the International Conference on Harmonization guidelines. The linearity ranges of these proposed method of the (Mixture (I)) were 25.0-400.0 µg/mL Amoxicillin, 0.5-8.0 µg/mL Vonoprazan, and 12.5-200.0 µg/mL Clarithromycin. And the linearity ranges of the (Mixture (II)) were 10.0-300.0 µg/mL Amoxicillin, 0.3-9.0 µg/mL Lansoprazole and 5.0-150.0 µg/mL Clarithromycin. This method was firstly applied for effective separation of Amoxicillin, Vonoprazan and Clarithromycin [Mixture (I)]. It fulfilled good repeatability, sensitivity, and accuracy (R.S.D. < 2.0%). The mean recoveries of the analytes in their Tri-Pak formulations were acceptable. The greenness of the developed chromatographic methods was assessed using an Eco-scale method and it was applied for content uniformity testing as per the United States Pharmacopoeia (USP) and the acceptance value of Amoxicillin, in Mixture (I) was 2.88, the acceptance values for Amoxicillin, Lansoprazole in Mixture (II) were 2.592, 2.424, respectively.
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Affiliation(s)
- Yomna A Salem
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Sinai University, Kantara Branch, Ismailia, 41636, Egypt.
| | - Samah A Elsabour
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Elsalehya El Gadida University, Elsalehya El Gadida, Sharkia, Egypt
| | - Amal A El-Masry
- Department of Medicinal Chemistry, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt.
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2
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Marron DP, Galvin CM, Dressel JM, Waymouth RM. Cobaltocene-Mediated Catalytic Hydride Transfer: Strategies for Electrocatalytic Hydrogenation. J Am Chem Soc 2024. [PMID: 38864712 DOI: 10.1021/jacs.4c02177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
The selective electrocatalytic hydrogenation of organics with transition metal hydrides is a promising strategy for electrosynthesis and energy storage. We report the electrocatalytic hydrogenation of acetone with a cyclopentadienone-iridium complex in a tandem electrocatalytic cycle with a cobaltocene mediator. The reductive protonation of cobaltocenium with mild acids generates (C5H5)CoI(C5H6) (CpCoI(CpH)), which functions as an electrocatalytic hydride mediator to deliver a hydride to cationic Ir(III) without generating hydrogen. Electrocatalytic hydride transfer by CpCoI(CpH) to a cationic Ir species leads to the efficient (Faradaic efficiency > 90%) electrohydrogenation of acetone, a valuable hydrogenation target as a liquid organic hydrogen carrier (LOHC). Hydride-transfer mediation presents a powerful strategy to generate metal hydrides that are inaccessible by stepwise electron/proton transfer.
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Affiliation(s)
- Daniel P Marron
- Department of Chemistry, Stanford University, Stanford, California 94306, United States
| | - Conor M Galvin
- Department of Chemistry, Stanford University, Stanford, California 94306, United States
| | - Julia M Dressel
- Department of Chemistry, Stanford University, Stanford, California 94306, United States
| | - Robert M Waymouth
- Department of Chemistry, Stanford University, Stanford, California 94306, United States
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3
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Wu X, Fan X, Xie S, Scodeller I, Wen X, Vangestel D, Cheng J, Sels B. Zinc-indium-sulfide favors efficient C - H bond activation by concerted proton-coupled electron transfer. Nat Commun 2024; 15:4967. [PMID: 38862582 PMCID: PMC11167015 DOI: 10.1038/s41467-024-49265-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 05/23/2024] [Indexed: 06/13/2024] Open
Abstract
C - H bond activation is a ubiquitous reaction that remains a major challenge in chemistry. Although semiconductor-based photocatalysis is promising, the C - H bond activation mechanism remains elusive. Herein, we report value-added coupling products from a wide variety of biomass and fossil-derived reagents, formed via C - H bond activation over zinc-indium-sulfides (Zn-In-S). Contrary to the commonly accepted stepwise electron-proton transfer pathway (PE-ET) for semiconductors, our experimental and theoretical studies evidence a concerted proton-coupled electron transfer (CPET) pathway. A pioneering microkinetic study, considering the relevant elementary steps of the surface chemistry, reveals a faster C - H activation with Zn-In-S because of circumventing formation of a charged radical, as it happens in PE-ET where it retards the catalysis due to strong site adsorption. For CPET over Zn-In-S, H abstraction, forming a neutral radical, is rate-limiting, but having lower energy barriers than that of PE-ET. The rate expressions derived from the microkinetics provide guidelines to rationally design semiconductor catalysis, e.g., for C - H activation, that is based on the CPET mechanism.
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Affiliation(s)
- Xuejiao Wu
- Center for Sustainable Catalysis and Engineering, Faculty of Bioscience Engineering, KU Leuven, Heverlee, 3001, Belgium.
| | - Xueting Fan
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Shunji Xie
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Ivan Scodeller
- Center for Sustainable Catalysis and Engineering, Faculty of Bioscience Engineering, KU Leuven, Heverlee, 3001, Belgium
| | - Xiaojian Wen
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Dario Vangestel
- Center for Sustainable Catalysis and Engineering, Faculty of Bioscience Engineering, KU Leuven, Heverlee, 3001, Belgium
| | - Jun Cheng
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Bert Sels
- Center for Sustainable Catalysis and Engineering, Faculty of Bioscience Engineering, KU Leuven, Heverlee, 3001, Belgium.
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4
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Panda S, Phan H, Dunietz EM, Brueggemeyer MT, Hota PK, Siegler MA, Jose A, Bhadra M, Solomon EI, Karlin KD. Intramolecular Phenolic H-Atom Abstraction by a N 3ArOH Ligand-Supported (μ-η 2:η 2-Peroxo)dicopper(II) Species Relevant to the Active Site Function of oxy-Tyrosinase. J Am Chem Soc 2024; 146:14942-14947. [PMID: 38775712 DOI: 10.1021/jacs.4c04402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Synthetic side-on peroxide-bound dicopper(II) (SP) complexes are important for understanding the active site structure/function of many copper-containing enzymes. This work highlights the formation of new {CuII(μ-η2:η2-O22-)CuII} complexes (with electronic absorption and resonance Raman (rR) spectroscopic characterization) using tripodal N3ArOH ligands at -135 °C, which spontaneously participate in intramolecular phenolic H-atom abstraction (HAA). This results in the generation of bis(phenoxyl radical)bis(μ-OH)dicopper(II) intermediates, substantiated by their EPR/UV-vis/rR spectroscopic signatures and crystal structural determination of a diphenoquinone dicopper(I) complex derived from ligand para-C═C coupling. The newly observed chemistry in these ligand-Cu systems is discussed with respect to (a) our Cu-MeAN (tridentate N,N,N',N',N″-pentamethyldipropylenetriamine)-derived model SP species, which was unreactive toward exogenous monophenol addition (J. Am. Chem. Soc. 2012, 134, 8513-8524), emphasizing the impact of intramolecularly tethered ArOH groups, and (b) recent advances in understanding the mechanism of action of the tyrosinase (Ty) enzyme.
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Affiliation(s)
- Sanjib Panda
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Hai Phan
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Eleanor M Dunietz
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | | | - Pradip Kumar Hota
- 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
| | - Anex Jose
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Mayukh Bhadra
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Kenneth D Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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5
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Ostermann N, Rotthowe N, Stückl AC, Siewert I. (Electro)chemical N 2 Splitting by a Molybdenum Complex with an Anionic PNP Pincer-Type Ligand. ACS ORGANIC & INORGANIC AU 2024; 4:329-337. [PMID: 38855335 PMCID: PMC11157508 DOI: 10.1021/acsorginorgau.3c00056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 02/12/2024] [Accepted: 02/14/2024] [Indexed: 06/11/2024]
Abstract
Molybdenum(III) complexes bearing pincer-type ligands are well-known catalysts for N2-to-NH3 reduction. We investigated herein the impact of an anionic PNP pincer-type ligand in a Mo(III) complex on the (electro)chemical N2 splitting ([LMoCl3]-, 1 -, LH = 2,6-bis((di-tert-butylphosphaneyl)methyl)-pyridin-4-one). The increased electron-donating properties of the anionic ligand should lead to a stronger degree of N2 activation. The catalyst is indeed active in N2-to-NH3 conversion utilizing the proton-coupled electron transfer reagent SmI2/ethylene glycol. The corresponding Mo(V) nitrido complex 2H exhibits similar catalytic activity as 1H and thus could represent a viable intermediate. The Mo(IV) nitrido complex 3 - is also accessible by electrochemical reduction of 1 - under a N2 atmosphere. IR- and UV/vis-SEC measurements suggest that N2 splitting occurs via formation of an "overreduced" but more stable [(L(N2)2Mo0)2μ-N2]2- dimer. In line with this, the yield in the nitrido complex increases with lower applied potentials.
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Affiliation(s)
- Nils Ostermann
- Georg-August-Universität
Göttingen, Institut für
Anorganische Chemie, Tammannstr.
4, Göttingen 37077, Germany
| | - Nils Rotthowe
- Georg-August-Universität
Göttingen, Institut für
Anorganische Chemie, Tammannstr.
4, Göttingen 37077, Germany
| | - A. Claudia Stückl
- Georg-August-Universität
Göttingen, Institut für
Anorganische Chemie, Tammannstr.
4, Göttingen 37077, Germany
| | - Inke Siewert
- Georg-August-Universität
Göttingen, Institut für
Anorganische Chemie, Tammannstr.
4, Göttingen 37077, Germany
- Georg-August-Universität
Göttingen, International Center
for Advanced Studies of Energy Conversion, Tammannstr. 6, Göttingen 37077, Germany
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6
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Chivington AD, Squire S, Yamamoto N, Pink M, Griffith MD, Fletcher J, Gao Y, Zadrozny JM, Smith JM. Trimethylsilyldiazomethane Disassembly at a Three-Fold Symmetric Iron Site. Inorg Chem 2024; 63:10221-10229. [PMID: 38780069 DOI: 10.1021/acs.inorgchem.4c00604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
The reaction of equimolar trimethylsilyldiazomethyllithium (LiTMSD) with high spin (S = 2) PhB(AdIm)3FeCl (PhB(AdIm)3- = tris(3-adamantylimidazol-2-ylidene)phenylborate) affords the corresponding N-nitrilimido complex PhB(AdIm)3Fe-N═N═C(SiMe3). This complex can be converted to the thermodynamically more favorable C-isocyanoamido isomer PhB(AdIm)3Fe-C═N═N(SiMe3) by reaction with an additional equivalent of LiTMSD. While the iron(II) complexes are four-coordinate, the diazomethane is bound side-on in the iron(I) congener PhB(AdIm)3Fe(N,N'-κ2-N2C(H)Si(CH3)3). The latter complex adopts high spin (S = 3/2) ground state and features an unusually weak C-H bond. Photolysis of the iron(II) complexes induces N═N bond cleavage, with the iron(II) cyanide PhB(AdIm)3Fe-C≡N and iron(IV) nitride PhB(AdIm)3Fe≡N complexes being the major products of the reaction. The same products are obtained when the iron(I) complex is photolyzed or treated with a fluoride source. The trimethylsilyldiazomethane-derived ligand disassembly reactions are contrasted with those observed for related tris(carbene)amine complexes.
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Affiliation(s)
- Austin D Chivington
- Department of Chemistry, 800 E. Kirkwood Ave, Indiana University, Bloomington, Indiana 47405, United States
| | - Sammie Squire
- Department of Chemistry, 800 E. Kirkwood Ave, Indiana University, Bloomington, Indiana 47405, United States
| | - Nobuyuki Yamamoto
- Department of Chemistry, 800 E. Kirkwood Ave, Indiana University, Bloomington, Indiana 47405, United States
| | - Maren Pink
- Department of Chemistry, 800 E. Kirkwood Ave, Indiana University, Bloomington, Indiana 47405, United States
| | - Morgan D Griffith
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Jess Fletcher
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Yafei Gao
- Department of Chemistry, 800 E. Kirkwood Ave, Indiana University, Bloomington, Indiana 47405, United States
| | - Joseph M Zadrozny
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Jeremy M Smith
- Department of Chemistry, 800 E. Kirkwood Ave, Indiana University, Bloomington, Indiana 47405, United States
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7
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Gentry NE, Kurimoto A, Cui K, Cleron JL, Xiang CM, Hammes-Schiffer S, Mayer JM. Hydrogen on Colloidal Gold Nanoparticles. J Am Chem Soc 2024; 146:14505-14520. [PMID: 38743444 DOI: 10.1021/jacs.4c00507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Colloidal gold nanoparticles (AuNPs) have myriad scientific and technological applications, but their fundamental redox chemistry is underexplored. Reported here are titration studies of oxidation and reduction reactions of aqueous AuNP colloids, which show that the AuNPs bind substantial hydrogen (electrons + protons) under mild conditions. The 5 nm AuNPs are reduced to a similar extent with reductants from borohydrides to H2 and are reoxidized back essentially to their original state by oxidants, including O2. The reactions were monitored via surface plasmon resonance (SPR) optical absorption, which was shown to be much more sensitive to surface H than to changes in solution conditions. Reductions with H2 occurred without pH changes, demonstrating that hydrogenation forms surface H rather than releasing H+. Computational studies suggested that an SPR blueshift was expected for H atom addition, while just electron addition likely would have caused a redshift. Titrations consistently showed a maximum redox change of the 5 nm NPs, independent of the reagent, corresponding to 9% of the total gold or ∼30% hydrogen surface coverage (∼370 H per AuNP). Larger AuNPs showed smaller maximum fractional surface coverages. We conclude that H binds to the edge, corner, and defect sites of the AuNPs, which explains the stoichiometric limitation and the size effect. The finding of substantial and stable hydrogen on the AuNP surface under mild reducing conditions has potential implications for various applications of AuNPs in reducing environments, from catalysis to biomedicine. This finding contrasts with the behavior of bulk gold and with the typical electron-focused perspective in this field.
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Affiliation(s)
- Noreen E Gentry
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Aiko Kurimoto
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Kai Cui
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Jamie L Cleron
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Claire M Xiang
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
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8
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Cooney SE, Schreiber E, Ferrigno BM, Matson EM. O 2 reduction via proton-coupled electron transfer by a V(III) aquo on a polyoxovanadate-alkoxide cluster. Chem Commun (Camb) 2024; 60:5610-5613. [PMID: 38713068 DOI: 10.1039/d4cc01331j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
We report the transfer of H-atoms from a reduced polyoxovanadate alkoxide [nOct4N][V6O6(OH2)(OMe)12] via concerted proton-electron transfer. Oxygen reduction is compared between bridging and terminal O-H bonds revealing similar mechanisms, providing new insight to design criteria for metal-oxide electrocatalysts that faciliate oxygen reduction by concerted-proton electron transfer.
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Affiliation(s)
- Shannon E Cooney
- Department of Chemistry, University of Rochester, Rochester NY 14627, USA.
| | - Eric Schreiber
- Department of Chemistry, University of Rochester, Rochester NY 14627, USA.
| | - Baela M Ferrigno
- Department of Chemistry, University of Rochester, Rochester NY 14627, USA.
| | - Ellen M Matson
- Department of Chemistry, University of Rochester, Rochester NY 14627, USA.
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9
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Trenerry MJ, Acosta M, Berry JF. Computational Analysis of Low Overpotential Ammonia Oxidation by Metal-Metal Bonded Ruthenium Catalysts, and Predictions for Related Osmium Catalysts. J Phys Chem A 2024; 128:4038-4051. [PMID: 38742806 DOI: 10.1021/acs.jpca.4c02490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The catalyzed electrochemical oxidation of ammonia to nitrogen (AOR) is an important fuel-cell half-reaction that underpins a future nitrogen-based energy economy. Our laboratory has reported spontaneous chemical and electrochemical oxidation of ammonia to dinitrogen via reaction of ammonia with the metal-metal bonded diruthenium complex Ru2(chp)4OTf (chp- = 2-chloro-6-hydroxypyridinate, TfO- = trifluoromethanesulfonate). This complex facilitates electrocatalytic ammonia oxidation at mild applied potentials of -255 mV vs ferrocene, which is the [Ru2(chp)4(NH3)]0/+ redox potential. We now report a comprehensive computational investigation of possible mechanisms for this reaction and electronic structure analysis of key intermediates therein. We extend this analysis to proposed second-generation electrocatalysts bearing structurally similar fhp and hmp (2-fluoro-6-hydroxypyridinate and 2-hydroxy-6-methylpyridinate, respectively) equatorial ligands, and we further expand this study from Ru2 to analogous Os2 cores. Predicted M24+/5+ redox potentials, which we expect to correlate with experimental AOR overpotential, depend strongly on the identity of the metal center, and to a lesser degree on the nature of the equatorial supporting ligand. Os2 complexes are easier to oxidize than analogous Ru2 complexes by ∼640 mV, on average. In contrast to mono-Ru catalysts, which oxidize ammonia via a rate-limiting activation of the strong N-H bond, we find lowest-energy reaction pathways for Ru2 and Os2 complexes that involve direct N-N bond formation onto electrophilic intermediates having terminal amido, imido, or nitrido groups. While transition state energies for Os2 complexes are high, those for Ru2 complexes are moderate and notably lower than those for mono-Ru complexes. We attribute these lower barriers to enhanced electrophilicity of the Ru2 intermediates, which is a consequence of their metal-metal bonded structure. Os2 intermediates are found to be, surprisingly, less electrophilic, and we suggest that Os2 complexes may require access to oxidation states higher than Os25+ in order to perform AOR at reasonable reaction rates.
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Affiliation(s)
- Michael J Trenerry
- Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706, United States
- Department of Chemistry, University of Minnesota - Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Milton Acosta
- Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706, United States
| | - John F Berry
- Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706, United States
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10
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Wu T, Puri A, Qiu YL, Ye D, Sarma R, Wang Y, Kowalewski T, Siegler MA, Swart M, Garcia-Bosch I. Tuning the Thermochemistry and Reactivity of a Series of Cu-Based 4H +/4e - Electron-Coupled-Proton Buffers. Inorg Chem 2024; 63:9014-9025. [PMID: 38723621 PMCID: PMC11110016 DOI: 10.1021/acs.inorgchem.4c00835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/08/2024] [Accepted: 04/30/2024] [Indexed: 05/21/2024]
Abstract
Electron-coupled-proton buffers (ECPBs) store and deliver protons and electrons in a reversible fashion. We have recently reported an ECPB based on Cu and a redox-active ligand that promoted 4H+/4e- reversible transformations (J. Am. Chem. Soc. 2022, 144, 16905). Herein, we report a series of Cu-based ECPBs in which the ability of these to accept and/or donate H• equivalents can be tuned via ligand modification. The thermochemistry of the 4H+/4e- ECPB equilibrium was determined using open-circuit potential measurements. The reactivity of the ECPBs against proton-coupled electron transfer (PCET) reagents was also analyzed, and the results obtained were rationalized based on the thermochemical parameters. Experimental and computational analysis of the thermochemistry of the H+/e- transfers involved in the 4H+/4e- ECPB transformations found substantial differences between the stepwise (namely, BDFE1, BDFE2, BDFE3, and BDFE4) and average bond dissociation free energy values (BDFEavg.). Our analysis suggests that this "redox unleveling" is critical to promoting the disproportionation and ligand-exchange reactions involved in the 4H+/4e- ECPB equilibria. The difference in BDFEavg. within the series of Cu-based ECPBs was found to arise from a substantial change in the redox potential (E1/2) upon modification of the ligand scaffold, which is not fully compensated for by a change in the acidity/basicity (pKa), suggesting "thermochemical decompensation".
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Affiliation(s)
- Tong Wu
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Ankita Puri
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yi Lin Qiu
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Daniel Ye
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Rajdeep Sarma
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yiwen Wang
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Tomasz Kowalewski
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | | | - Marcel Swart
- University
of Girona, Campus Montilivi (Ciències), Plaça de Sant Domènec, 17004 Girona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Isaac Garcia-Bosch
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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11
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Hota PK, Jose A, Panda S, Dunietz EM, Herzog AE, Wojcik L, Le Poul N, Belle C, Solomon EI, Karlin KD. Coordination Variations within Binuclear Copper Dioxygen-Derived (Hydro)Peroxo and Superoxo Species; Influences upon Thermodynamic and Electronic Properties. J Am Chem Soc 2024; 146:13066-13082. [PMID: 38688016 PMCID: PMC11161030 DOI: 10.1021/jacs.3c14422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Copper ion is a versatile and ubiquitous facilitator of redox chemical and biochemical processes. These include the binding of molecular oxygen to copper(I) complexes where it undergoes stepwise reduction-protonation. A detailed understanding of thermodynamic relationships between such reduced/protonated states is key to elucidate the fundamentals of the chemical/biochemical processes involved. The dicopper(I) complex [CuI2(BPMPO-)]1+ {BPMPOH = 2,6-bis{[(bis(2-pyridylmethyl)amino]methyl}-4-methylphenol)} undergoes cryogenic dioxygen addition; further manipulations in 2-methyltetrahydrofuran generate dicopper(II) peroxo [CuII2(BPMPO-)(O22-)]1+, hydroperoxo [CuII2(BPMPO-)(-OOH)]2+, and superoxo [CuII2(BPMPO-)(O2•-)]2+ species, characterized by UV-vis, resonance Raman and electron paramagnetic resonance (EPR) spectroscopies, and cold spray ionization mass spectrometry. An unexpected EPR spectrum for [CuII2(BPMPO-)(O2•-)]2+ is explained by the analysis of its exchange-coupled three-spin frustrated system and DFT calculations. A redox equilibrium, [CuII2(BPMPO-)(O22-)]1+ ⇄ [CuII2(BPMPO-)(O2•-)]2+, is established utilizing Me8Fc+/Cr(η6-C6H6)2, allowing for [CuII2(BPMPO-)(O2•-)]2+/[CuII2(BPMPO-)(O22-)]1+ reduction potential calculation, E°' = -0.44 ± 0.01 V vs Fc+/0, also confirmed by cryoelectrochemical measurements (E°' = -0.40 ± 0.01 V). 2,6-Lutidinium triflate addition to [CuII2(BPMPO-)(O22-)]1+ produces [CuII2(BPMPO-)(-OOH)]2+; using a phosphazene base, an acid-base equilibrium was achieved, pKa = 22.3 ± 0.7 for [CuII2(BPMPO-)(-OOH)]2+. The BDFEOO-H = 80.3 ± 1.2 kcal/mol, as calculated for [CuII2(BPMPO-)(-OOH)]2+; this is further substantiated by H atom abstraction from O-H substrates by [CuII2(BPMPO-)(O2•-)]2+ forming [CuII2(BPMPO-)(-OOH)]2+. In comparison to known analogues, the thermodynamic and spectroscopic properties of [CuII2(BPMPO-)] O2-derived adducts can be accounted for based on chelate ring size variations built into the BPMPO- framework and the resulting enhanced CuII-ion Lewis acidity.
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Affiliation(s)
- Pradip Kumar Hota
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Anex Jose
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Sanjib Panda
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Eleanor M Dunietz
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Austin E Herzog
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Laurianne Wojcik
- UMR CNRS 6521, Université de Bretagne Occidentale, 6 Avenue Le Gorgeu, CS 93837, Brest Cedex 3 29238, France
| | - Nicolas Le Poul
- UMR CNRS 6521, Université de Bretagne Occidentale, 6 Avenue Le Gorgeu, CS 93837, Brest Cedex 3 29238, France
| | - Catherine Belle
- Université Grenoble-Alpes, CNRS, DCM, UMR 5250, Grenoble 38058, France
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Kenneth D Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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12
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Garrido-Barros P, Romero CG, Winkler JR, Peters JC. Intermolecular Proton-Coupled Electron Transfer Reactivity from a Persistent Charge-Transfer State for Reductive Photoelectrocatalysis. J Am Chem Soc 2024; 146:12750-12757. [PMID: 38669102 PMCID: PMC11082884 DOI: 10.1021/jacs.4c02610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 04/05/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024]
Abstract
Interest in applying proton-coupled electron transfer (PCET) reagents in reductive electro- and photocatalysis requires strategies that mitigate the competing hydrogen evolution reaction. Photoexcitation of a PCET donor to a charge-separated state (CSS) can produce a powerful H-atom donor capable of being electrochemically recycled at a comparatively anodic potential corresponding to its ground state. However, the challenge is designing a mediator with a sufficiently long-lived excited state for bimolecular reactivity. Here, we describe a powerful ferrocene-derived photoelectrochemical PCET mediator exhibiting an unusually long-lived CSS (τ ∼ 0.9 μs). In addition to detailed photophysical studies, proof-of-concept stoichiometric and catalytic proton-coupled reductive transformations are presented, which illustrate the promise of this approach.
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Affiliation(s)
| | | | - Jay R. Winkler
- Division of Chemistry and Chemical
Engineering, California Institute of Technology
(Caltech), Pasadena, California 91125, United States
| | - Jonas C. Peters
- Division of Chemistry and Chemical
Engineering, California Institute of Technology
(Caltech), Pasadena, California 91125, United States
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13
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Thomas J, Mokkawes T, Senft L, Dey A, Gordon JB, Ivanovic-Burmazovic I, de Visser SP, Goldberg DP. Axial Ligation Impedes Proton-Coupled Electron-Transfer Reactivity of a Synthetic Compound-I Analogue. J Am Chem Soc 2024; 146:12338-12354. [PMID: 38669456 DOI: 10.1021/jacs.3c08950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
The nature of the axial ligand in high-valent iron-oxo heme enzyme intermediates and related synthetic catalysts is a critical structural element for controlling proton-coupled electron-transfer (PCET) reactivity of these species. Herein, we describe the generation and characterization of three new 6-coordinate, iron(IV)-oxo porphyrinoid-π-cation-radical complexes and report their PCET reactivity together with a previously published 5-coordinate analogue, FeIV(O)(TBP8Cz+•) (TBP8Cz = octakis(p-tert-butylphenyl)corrolazinato3-) (2) (Cho, K. A high-valent iron-oxo corrolazine activates C-H bonds via hydrogen-atom transfer. J. Am. Chem. Soc. 2012, 134, 7392-7399). The new complexes FeIV(O)(TBP8Cz+•)(L) (L = 1-methyl imidazole (1-MeIm) (4a), 4-dimethylaminopyridine (DMAP) (4b), cyanide (CN-)(4c)) can be generated from either oxidation of the ferric precursors or by addition of L to the Compound-I (Cpd-I) analogue at low temperatures. These complexes were characterized by UV-vis, electron paramagnetic resonance (EPR), and Mössbauer spectroscopies, and cryospray ionization mass spectrometry (CSI-MS). Kinetic studies using 4-OMe-TEMPOH as a test substrate indicate that coordination of a sixth axial ligand dramatically lowers the PCET reactivity of the Cpd-I analogue (rates up to 7000 times slower). Extensive density functional theory (DFT) calculations together with the experimental data show that the trend in reactivity with the axial ligands does not correlate with the thermodynamic driving force for these reactions or the calculated strengths of the O-H bonds being formed in the FeIV(O-H) products, pointing to non-Bell-Evans-Polanyi behavior. However, the PCET reactivity does follow a trend with the bracketed reduction potential of Cpd-I analogues and calculated electron affinities. The combined data suggest a concerted mechanism (a concerted proton electron transfer (CPET)) and an asynchronous movement of the electron/proton pair in the transition state.
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Affiliation(s)
- Jithin Thomas
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Thirakorn Mokkawes
- The Manchester Institute of Biotechnology and Department of Chemical Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Laura Senft
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr., 5-13, Haus D, 81377 München, Germany
| | - Aniruddha Dey
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Jesse B Gordon
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Ivana Ivanovic-Burmazovic
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr., 5-13, Haus D, 81377 München, Germany
| | - Sam P de Visser
- The Manchester Institute of Biotechnology and Department of Chemical Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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14
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Niklas JE, Otte KS, Studvick CM, Roy Chowdhury S, Vlaisavljevich B, Bacsa J, Kleemiss F, Popov IA, La Pierre HS. A tetrahedral neptunium(V) complex. Nat Chem 2024:10.1038/s41557-024-01529-6. [PMID: 38710831 DOI: 10.1038/s41557-024-01529-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 04/05/2024] [Indexed: 05/08/2024]
Abstract
Neptunium is an actinide element sourced from anthropogenic production, and, unlike naturally abundant uranium, its coordination chemistry is not well developed in all accessible oxidation states. High-valent neptunium generally requires stabilization from at least one metal-ligand multiple bond, and departing from this structural motif poses a considerable challenge. Here we report a tetrahedral molecular neptunium(V) complex ([Np5+(NPC)4][B(ArF5)4], 1-Np) (NPC = [NPtBu(pyrr)2]-; tBu = C(CH3)3; pyrr = pyrrolidinyl (N(C2H4)2); B(ArF5)4 = tetrakis(2,3,4,5,6-pentafluourophenyl)borate). Single-crystal X-ray diffraction, solution-state spectroscopy and density functional theory studies of 1-Np and the product of its proton-coupled electron transfer (PCET) reaction, 2-Np, demonstrate the unique bonding that stabilizes this reactive ion and establishes the thermochemical and kinetic parameters of PCET in a condensed-phase transuranic complex. The isolation of this four-coordinate, neptunium(V) complex reveals a fundamental reaction pathway in transuranic chemistry.
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Affiliation(s)
- Julie E Niklas
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
| | - Kaitlyn S Otte
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
| | - Chad M Studvick
- Department of Chemistry, The University of Akron, Akron, OH, USA
| | | | | | - John Bacsa
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
| | - Florian Kleemiss
- Institut für Anorganische Chemie, RWTH Aachen University, Aachen, Germany
| | - Ivan A Popov
- Department of Chemistry, The University of Akron, Akron, OH, USA.
| | - Henry S La Pierre
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA.
- Nuclear and Radiological Engineering and Medical Physics Program, School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA.
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15
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Shen GB, Luo GZ, Qian BC, Zhu XQ. Evaluation of Organic Hydride/Acid Pairs as a Type of Thermodynamic-Potential-Regulated Multisite Proton-Coupled Electron Transfer Reagents. J Org Chem 2024; 89:6205-6221. [PMID: 38632842 DOI: 10.1021/acs.joc.4c00208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2024]
Abstract
Organic hydride/acid pairs have been reported as multisite proton-coupled electron transfer (MS-PCET) reagents in reductive MS-PCET reactions recently. Since the key step for an organic hydride/acid pair acting as an MS-PCET reagent is a chemical process of the organic hydride/acid pair releasing a formal hydrogen atom, the bond dissociation free energy of the organic hydride/acid pair releasing a formal hydrogen atom is a valuable thermodynamic parameter for objectively evaluating the thermodynamic potential for an organic hydride/acid pair to act as an MS-PCET reagent. Now, organic hydride/acid pairs of 216 organic hydrides have been demonstrated to be a potential type of thermodynamically potential-regulated MS-PCET reagent. Without a doubt, organic hydride/acid pairs reflect the change of N-substituted organic hydrides from simple hydride reductants to thermodynamically-regulated MS-PCET reagents, which could significantly expand the availability of novel MS-PCET reagents.
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Affiliation(s)
- Guang-Bin Shen
- College of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Guang-Ze Luo
- College of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Bao-Chen Qian
- College of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin 300071, China
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16
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Saju A, Crawley MR, MacMillan SN, Lacy DC. Manganese(III) Nitrate Complexes as Bench-Stable Powerful Oxidants. J Am Chem Soc 2024; 146:11616-11621. [PMID: 38639535 DOI: 10.1021/jacs.4c03411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
We report herein a convenient one-pot synthesis for the shelf-stable molecular complex [Mn(NO3)3(OPPh3)2] (2) and describe the properties that make it a powerful and selective one-electron oxidation (deelectronation) reagent. 2 has a high reduction potential of 1.02 V versus ferrocene (MeCN) (1.65 vs normal hydrogen electrode), which is one the highest known among readily available redox agents used in chemical synthesis. 2 exhibits stability toward air in the solid state, can be handled with relative ease, and is soluble in most common laboratory solvents such as MeCN, dichloromethane, and fluorobenzene. 2 is substitutionally labile with respect to the coordinated (pseudo)halide ions enabling the synthesis of other new Mn(III) nitrato complexes also with high reduction potentials ranging from 0.6 to 1.0 V versus ferrocene.
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Affiliation(s)
- Ananya Saju
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Matthew R Crawley
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - David C Lacy
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, United States
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17
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Jiang N, Darù A, Kunstelj Š, Vitillo JG, Czaikowski ME, Filatov AS, Wuttig A, Gagliardi L, Anderson JS. Catalytic, Spectroscopic, and Theoretical Studies of Fe 4S 4-Based Coordination Polymers as Heterogenous Coupled Proton-Electron Transfer Mediators for Electrocatalysis. J Am Chem Soc 2024; 146:12243-12252. [PMID: 38651361 DOI: 10.1021/jacs.4c03726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Iron-sulfur clusters play essential roles in biological systems, and thus synthetic [Fe4S4] clusters have been an area of active research. Recent studies have demonstrated that soluble [Fe4S4] clusters can serve as net H atom transfer mediators, improving the activity and selectivity of a homogeneous Mn CO2 reduction catalyst. Here, we demonstrate that incorporating these [Fe4S4] clusters into a coordination polymer enables heterogeneous H atom transfer from an electrode surface to a Mn complex dissolved in solution. A previously reported solution-processable Fe4S4-based coordination polymer was successfully deposited on the surfaces of different electrodes. The coated electrodes serve as H atom transfer mediators to a soluble Mn CO2 reduction catalyst displaying good product selectivity for formic acid. Furthermore, these electrodes are recyclable with a minimal decrease in activity after multiple catalytic cycles. The heterogenization of the mediator also enables the characterization of solution-phase and electrode surface species separately. Surface enhanced infrared absorption spectroscopy (SEIRAS) reveals spectroscopic signatures for an in situ generated active Mn-H species, providing a more complete mechanistic picture for this system. The active species, reaction mechanism, and the protonation sites on the [Fe4S4] clusters were further confirmed by density functional theory calculations. The observed H atom transfer reactivity of these coordination polymer-coated electrodes motivates additional applications of this composite material in reductive H atom transfer electrocatalysis.
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Affiliation(s)
- Ningxin Jiang
- Department of Chemistry, University of Chicago, Chicago,Illinois 60637, United States
| | - Andrea Darù
- Department of Chemistry, University of Chicago, Chicago,Illinois 60637, United States
| | - Špela Kunstelj
- Department of Chemistry, University of Chicago, Chicago,Illinois 60637, United States
| | - Jenny G Vitillo
- Department of Science and High Technology and INSTM, Università degli Studi dell'Insubria, Como 22100, Italy
| | - Maia E Czaikowski
- Department of Chemistry, University of Chicago, Chicago,Illinois 60637, United States
| | - Alexander S Filatov
- Department of Chemistry, University of Chicago, Chicago,Illinois 60637, United States
| | - Anna Wuttig
- Department of Chemistry, University of Chicago, Chicago,Illinois 60637, United States
| | - Laura Gagliardi
- Department of Chemistry, University of Chicago, Chicago,Illinois 60637, United States
- Pritzker School of Molecular Engineering, James Franck Institute, University of Chicago, Chicago,Illinois 60637, United States
| | - John S Anderson
- Department of Chemistry, University of Chicago, Chicago,Illinois 60637, United States
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18
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Zhao W, Jin K, Xu P, Wu F, Fu L, Xu B. Bismuth Telluride Supported Sub-1 nm Polyoxometalate Cluster for High-Efficiency Thermoelectric Energy Conversion. NANO LETTERS 2024; 24:5361-5370. [PMID: 38630986 DOI: 10.1021/acs.nanolett.4c01304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/19/2024]
Abstract
Size plays a crucial role in chemistry and material science. Subnanometer polyoxometalate (POM) clusters have gained attention in various fields, but their use in thermoelectrics is still limited. To address this issue, we propose the POM clusters as an effective second phase to enhance the thermoelectric properties of Bi0.4Sb1.6Te3. Thanks to their subnanometer size, POM clusters improve electrical transport behavior through the superposition of atomic orbitals and the interfacial scattering effect. Furthermore, their ultrasmall size strongly reduces thermal conductivity. Consequently, the introduction of a mere 0.1 mol % of POM into the Bi0.4Sb1.6Te3 matrix realizes a state-of-the-art zT value of 1.46 at 348 K, a 45% enhancement over Bi0.4Sb1.6Te3 (1.01), along with a maximum thermoelectric-conversion efficiency of the integrated module of 6.0%. The enhancement of carrier mobility and the suppression of thermal conduction achieved by introducing the subnanometer clusters hold promise for various applications, such as electronic devices and thermal management.
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Affiliation(s)
- Wei Zhao
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China
| | - Kangpeng Jin
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China
| | - Pengfei Xu
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China
| | - Fanshi Wu
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China
| | - Liangwei Fu
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China
| | - Biao Xu
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, People's Republic of China
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19
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Proe KR, Towarnicky A, Fertig A, Lu Z, Mpourmpakis G, Matson EM. Impact of Surface Ligand Identity and Density on the Thermodynamics of H Atom Uptake at Polyoxovanadate-Alkoxide Surfaces. Inorg Chem 2024; 63:7206-7217. [PMID: 38592922 DOI: 10.1021/acs.inorgchem.3c04435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
An understanding of how molecular structure influences the thermodynamics of H atom transfer is critical to designing efficient catalysts for reductive chemistries. Herein, we report experimental and theoretical investigations summarizing structure-function relationships of polyoxovanadate-alkoxides that influence bond dissociation free energies of hydroxide ligands located at the surface of the cluster. We evaluate the thermochemical descriptors of O-H bond strength for a series of clusters, namely [V6O13-x(OH)x(TRIOLR)2]-2 (x = 2, 4, 6; R = NO2, Me) and [V6O11-x(OMe)2(OH)x(TRIOLNO2)2]-2, via computational analysis and open circuit potential measurements. Our findings reveal that modifications to the TRIOL ligand (e.g., changing from the previously reported electron withdrawing nitro-backed ligand to the electron-donating methyl variant) have limited influence on the strength of surface O-H bonds as a result of near complete thermodynamic compensation in these systems (i.e., correlated changes in redox potential and cluster basicity). In contrast, changes in surface density of alkoxide ligands via direct alkoxylation of the polyoxovanadate-alkoxide surface result in measurable increases in bond dissociation free energies of surface O-H bonds for the mixed-valent derivatives. Our findings indicate that the extent of (de)localization of electron density across the cluster core has an impact on the bond dissociation free energies of surface O-H bonds across all oxidation states of the assembly.
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Affiliation(s)
- Kathryn R Proe
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Andreas Towarnicky
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Alex Fertig
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Zhou Lu
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Giannis Mpourmpakis
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Ellen M Matson
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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20
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Lu Z, Cooney SE, McKone JR, Matson EM. Selective Hydrogenation of Azobenzene to Hydrazobenzene via Proton-Coupled Electron Transfer from a Polyoxotungstate Cluster. JACS AU 2024; 4:1310-1314. [PMID: 38665657 PMCID: PMC11041919 DOI: 10.1021/jacsau.4c00127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 03/05/2024] [Accepted: 03/14/2024] [Indexed: 04/28/2024]
Abstract
In this report, we describe proton-coupled electron transfer (PCET) reactivity at the surface of the Keggin-type polyoxotungstate cluster [nBu4N]3[PWVI12O40] (PW12) in acetonitrile. Bond dissociation free energies (BDFEs) of the O-H groups generated upon reduction of PW12 in the presence of acid are determined through the construction of a potential-pKa diagram. The surface O-H bonds are found to be weak (BDFE(O-H)avg < 48 kcal mol-1), comparable to the BDFE of H2. This is consistent with the observed formation of H2 upon addition of a suitably strong organic acid, H2NPh2+ (pKa MeCN = 5.98), to the reduced form of the cluster. The one-electron reduced form of PW12 is isolated and used in conjunction with acid to realize the stoichiometric semihydrogenation of azobenzene via PCET from the surface of the reduced cluster.
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Affiliation(s)
- Zhou Lu
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Shannon E. Cooney
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - James R. McKone
- Departments
of Chemical and Petroleum Engineering and Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Ellen M. Matson
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
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21
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Kayne M, Murphy PS, Kwon YM, Lee Y, Jackson TA, Wang D. Generation, Characterization and Reactivity of a High-Valent Mononuclear Cobalt(IV)-Diazide Complex. Chemistry 2024:e202401218. [PMID: 38644346 DOI: 10.1002/chem.202401218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Accepted: 04/20/2024] [Indexed: 04/23/2024]
Abstract
High-valent Fe(IV)=O intermediates of metalloenzymes have inspired numerous efforts to generate synthetic analogs to mimic and understand their substrate oxidation reactivities. However, high-valent M(IV) complexes of late transition metals are rare. We have recently reported a novel Co(IV)-dinitrate complex (1-NO3) that activates sp3 C-H bonds up to 87 kcal/mol. In this work, we have shown that the nitrate ligands in 1-NO3 can be replaced by azide, a more basic coordinating base, resulting in the formation of a more potent Co(IV)-diazide species (1-N3) that reacts with substrates (hydrocarbons and phenols) at faster rate constants and activates stronger C-H bonds than the parent complex 1-NO3. We have characterized 1-N3 employing a combination of spectroscopic and computational approaches. Our results clearly show that the coordination of azide leads to the modulation of the Co(IV) electronic structure and the Co(IV/III) redox potential. Together with the higher basicity of azide, these thermodynamic parameters contribute to the higher driving forces of 1-N3 than 1-NO3 for C-H bond activation. Our discoveries are thus insightful for designing more reactive bio-inspired high-valent late transition metal complexes for activating inert aliphatic hydrocarbons.
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Affiliation(s)
- Michael Kayne
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, 59812, United States
| | - Patrick S Murphy
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Yubin M Kwon
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, 59812, United States
| | - Yuri Lee
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Timothy A Jackson
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Dong Wang
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, 59812, United States
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22
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Nedzbala HS, Westbroek D, Margavio HRM, Yang H, Noh H, Magpantay SV, Donley CL, Kumbhar AS, Parsons GN, Mayer JM. Photoelectrochemical Proton-Coupled Electron Transfer of TiO 2 Thin Films on Silicon. J Am Chem Soc 2024; 146:10559-10572. [PMID: 38564642 DOI: 10.1021/jacs.4c00014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
TiO2 thin films are often used as protective layers on semiconductors for applications in photovoltaics, molecule-semiconductor hybrid photoelectrodes, and more. Experiments reported here show that TiO2 thin films on silicon are electrochemically and photoelectrochemically reduced in buffered acetonitrile at potentials relevant to photoelectrocatalysis of CO2 reduction, N2 reduction, and H2 evolution. On both n-type Si and irradiated p-type Si, TiO2 reduction is proton-coupled with a 1e-:1H+ stoichiometry, as demonstrated by the Nernstian dependence of the Ti4+/3+ E1/2 on the buffer pKa. Experiments were conducted with and without illumination, and a photovoltage of ∼0.6 V was observed across 20 orders of magnitude in proton activity. The 4 nm films are almost stoichiometrically reduced under mild conditions. The reduced films catalytically transfer protons and electrons to hydrogen atom acceptors, based on cyclic voltammogram, bulk electrolysis, and other mechanistic evidence. TiO2/Si thus has the potential to photoelectrochemically generate high-energy H atom carriers. Characterization of the TiO2 films after reduction reveals restructuring with the formation of islands, rendering TiO2 films as a potentially poor choice as protecting films or catalyst supports under reducing and protic conditions. Overall, this work demonstrates that atomic layer deposition TiO2 films on silicon photoelectrodes undergo both chemical and morphological changes upon application of potentials only modestly negative of RHE in these media. While the results should serve as a cautionary tale for researchers aiming to immobilize molecular monolayers on "protective" metal oxides, the robust proton-coupled electron transfer reactivity of the films introduces opportunities for the photoelectrochemical generation of reactive charge-carrying mediators.
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Affiliation(s)
- Hannah S Nedzbala
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Dalaney Westbroek
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Hannah R M Margavio
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27603, United States
| | - Hyuenwoo Yang
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27603, United States
| | - Hyunho Noh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Samantha V Magpantay
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Carrie L Donley
- Department of Chemistry, Chapel Hill Analytical and Nanofabrication Laboratory (CHANL), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Amar S Kumbhar
- Department of Chemistry, Chapel Hill Analytical and Nanofabrication Laboratory (CHANL), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Gregory N Parsons
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27603, United States
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
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23
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Li F, Lan J, Li X, Chung LW. A Synergistic Bimetallic Ti/Co-Catalyzed Isomerization of Epoxides to Allylic Alcohols Enabled by Two-State Reactivity. Inorg Chem 2024; 63:6285-6295. [PMID: 38517250 DOI: 10.1021/acs.inorgchem.4c00011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
Isomerization of epoxides into versatile allylic alcohols is an atom-economical synthetic method to afford vicinal bifunctional groups. Comprehensive density functional theory (DFT) calculations were carried out to elucidate the complex mechanism of a bimetallic Ti/Co-catalyzed selective isomerization of epoxides to allyl alcohols by examining several possible pathways. Our results suggest a possible mechanism involving (1) radical-type epoxide ring opening catalyzed by Cp2Ti(III)Cl leading to a Ti(IV)-bound β-alkyl radical, (2) hydrogen-atom transfer (HAT) catalyzed by the Co(II) catalyst to form the Ti(IV)-enolate and Co(III)-H intermediate, (3) protonation to give the alcohols, and (4) proton abstraction to form the Co(I) species followed by electron transfer to regenerate the active Co(II) and Ti(III) species. Moreover, bimetallic catalysis and two-state reactivity enable the key rate-determining HAT step. Furthermore, a subtle balance between dispersion-driven bimetallic processes and entropy-driven monometallic processes determines the most favorable pathway, among which the monometallic process is energetically more favorable in all steps except the vital hydrogen-atom transfer step. Our study should provide an in-depth mechanistic understanding of bimetallic catalysis.
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Affiliation(s)
- Fangfang Li
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jialing Lan
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen 518055, China
| | - Xin Li
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen 518055, China
| | - Lung Wa Chung
- Shenzhen Grubbs Institute and Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen 518055, China
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24
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Almquist CC, Rajeshkumar T, Jayaweera HDAC, Removski N, Zhou W, Gelfand BS, Maron L, Piers WE. Oxidation-induced ambiphilicity triggers N-N bond formation and dinitrogen release in octahedral terminal molybdenum(v) nitrido complexes. Chem Sci 2024; 15:5152-5162. [PMID: 38577349 PMCID: PMC10988598 DOI: 10.1039/d4sc00090k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 02/16/2024] [Indexed: 04/06/2024] Open
Abstract
Coupling of octahedral, terminal d1 molybdenum(v) nitrido complexes supported by a dianionic pentadentate ligand via N-N bond formation to give μ-dinitrogen complexes was found to be thermodynamically feasible but faces significant kinetic barriers. However, upon oxidation, a kinetically favored nucleophilic/electrophilic N-N bond forming mechanism was enabled to give monocationic μ-dinitrogen dimers. Computational and experimental evidence for this "oxidation-induced ambiphilic nitrido coupling" mechanism is presented. The factors influencing release of dinitrogen from the resulting μ-dinitrogen dimers were also probed and it was found that further oxidation to a dicationic species is required to induce (very rapid) loss of dinitrogen. The mechanistic path discovered for N-N bond formation and dinitrogen release follows an ECECC sequence (E = "electrochemical step"; C = "chemical step"). Experimental evidence for the intermediacy of a highly electrophilic, cationic d0 molybdenum(vi) nitrido in the N-N bond forming mechanism via trapping with an isonitrile reagent is also discussed. Together these results are relevant to the development of molecular catalysts capable of mediating ammonia oxidation to dihydrogen and dinitrogen.
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Affiliation(s)
- C Christopher Almquist
- Department of Chemistry, University of Calgary 2500 University Drive NW Calgary Alberta T2N 1N4 Canada
| | | | - H D A Chathumal Jayaweera
- Department of Chemistry, University of Calgary 2500 University Drive NW Calgary Alberta T2N 1N4 Canada
| | - Nicole Removski
- Department of Chemistry, University of Calgary 2500 University Drive NW Calgary Alberta T2N 1N4 Canada
| | - Wen Zhou
- Department of Chemistry, University of Calgary 2500 University Drive NW Calgary Alberta T2N 1N4 Canada
| | - Benjamin S Gelfand
- Department of Chemistry, University of Calgary 2500 University Drive NW Calgary Alberta T2N 1N4 Canada
| | - Laurent Maron
- LPCNO, Université de Toulouse, INSA UPS Toulouse France
| | - Warren E Piers
- Department of Chemistry, University of Calgary 2500 University Drive NW Calgary Alberta T2N 1N4 Canada
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25
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Hess KM, Leach IF, Wijtenhorst L, Lee H, Klein JEMN. Valence Tautomerism Induced Proton Coupled Electron Transfer:X-H Bond Oxidation with a Dinuclear Au(II) Hydroxide Complex. Angew Chem Int Ed Engl 2024; 63:e202318916. [PMID: 38324462 DOI: 10.1002/anie.202318916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/25/2024] [Accepted: 02/05/2024] [Indexed: 02/09/2024]
Abstract
We report the preparation and characterization of the dinuclear AuII hydroxide complex AuII 2(L)2(OH)2 (L=N,N'-bis (2,6-dimethyl) phenylformamidinate) and study its reactivity towards weak X-H bonds. Through the interplay of kinetic analysis and computational studies, we demonstrate that the oxidation of cyclohexadiene follows a concerted proton-coupled electron transfer (cPCET) mechanism, a rare type of reactivity for Au complexes. We find that the Au-Au σ-bond undergoes polarization in the PCET event leading to an adjustment of oxidation levels for both Au centers prior to C(sp3)-H bond cleavage. We thus describe the oxidation event as a valence tautomerism-induced PCET where the basicity of one reduced Au-OH unit provides a proton acceptor and the second more oxidized Au center serves as an electron acceptor. The coordination of these events allows for unprecedented radical-type reactivity by a closed shell AuII complex.
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Affiliation(s)
- Kristopher M Hess
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747, AG Groningen, The Netherlands
| | - Isaac F Leach
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747, AG Groningen, The Netherlands
| | - Lisa Wijtenhorst
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747, AG Groningen, The Netherlands
| | - Hangyul Lee
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747, AG Groningen, The Netherlands
| | - Johannes E M N Klein
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747, AG Groningen, The Netherlands
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26
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Dong X, Shi X, Cui Z, Dai W, Dong F. Dynamic Hydroxylation Enhances Hydrogen Atom Abstraction from Water for Nitrogen Fixation Revealed by Isotope Labeling in Situ Fourier-Transform Infrared Spectroscopy. ACS NANO 2024; 18:9670-9677. [PMID: 38516986 DOI: 10.1021/acsnano.4c00975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
Employing water as a hydrogen source to participate in the hydrogen atom transfer (HAT) process is a low-cost and carbon-free process demonstrating great economic and environmental potential in catalysis. However, the low efficiency of hydrogen atom abstraction from water leads to slow kinetics of HAT for most hydrogenative reactions. Here, we prepared ultrathin Bi4O5Cl2 nanosheets where the surface can be in situ reconstructed via hydroxylation under light illumination to facilitate the abstraction of hydrogen atoms from pure water for efficient nitrogen fixation. Consequently, the isotope labeling in situ Fourier-transform infrared spectroscopy (FT-IR) involving H2O and D2O has clearly revealed that the hydroxyl groups tend to be adsorbed on the chloride vacancy sites on the Bi4O5Cl2 surface to form hydroxylated surfaces, where the hydroxylated photocatalyst surface enables partial dehydrogenation of water into H2O2, allowing the utilization of H atoms for efficient of N2 hydrogenation via HAT steps. This work elucidates the in-depth reaction mechanism of hydrogen atom extraction from H2O molecules via the light-generated chloride vacancy to promote photocatalytic nitrogen fixation, ultimately enabling the inspiration and providing crucial rules for the design of important functional materials that can efficiently deliver active hydrogen for chemical synthesis.
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Affiliation(s)
- Xing'an Dong
- Research Center for Carbon-Neutral Environmental & Energy Technology, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, People's Republic of China
- College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 401331, People's Republic of China
| | - Xian Shi
- School of Chemistry and Environmental Engineering, Sichuan University of Science & Engineering, Zigong 643000, People's Republic of China
| | - Zhihao Cui
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Weidong Dai
- Research Center for Carbon-Neutral Environmental & Energy Technology, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, People's Republic of China
| | - Fan Dong
- Research Center for Carbon-Neutral Environmental & Energy Technology, Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 611731, People's Republic of China
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27
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Huang KY, Yang ZQ, Yang MR, Chen TS, Tang S, Sun WM, Yao Q, Deng HH, Chen W, Xie J. Unraveling a Concerted Proton-Coupled Electron Transfer Pathway in Atomically Precise Gold Nanoclusters. J Am Chem Soc 2024; 146:8706-8715. [PMID: 38487838 DOI: 10.1021/jacs.4c01180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
Metal nanoclusters (MNCs) represent a promising class of materials for catalytic carbon dioxide and proton reduction as well as dihydrogen oxidation. In such reactions, multiple proton-coupled electron transfer (PCET) processes are typically involved, and the current understanding of PCET mechanisms in MNCs has primarily focused on the sequential transfer mode. However, a concerted transfer pathway, i.e., concerted electron-proton transfer (CEPT), despite its potential for a higher catalytic rate and lower reaction barrier, still lacks comprehensive elucidation. Herein, we introduce an experimental paradigm to test the feasibility of the CEPT process in MNCs, by employing Au18(SR)14 (SR denotes thiolate ligand), Au22(SR)18, and Au25(SR)18- as model clusters. Detailed investigations indicate that the photoinduced PCET reactions in the designed system proceed via an CEPT pathway. Furthermore, the rate constants of gold nanoclusters (AuNCs) have been found to be correlated with both the size of the cluster and the flexibility of the Au-S framework. This newly identified PCET behavior in AuNCs is prominently different from that observed in semiconductor quantum dots and plasmonic metal nanoparticles. Our findings are of crucial importance for unveiling the catalytic mechanisms of quantum-confined metal nanomaterials and for the future rational design of more efficient catalysts.
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Affiliation(s)
- Kai-Yuan Huang
- Higher Educational Key Laboratory for Nano Biomedical Technology of Fujian Province, Department of Pharmaceutical Analysis, Fujian Medical University, Fuzhou 350004, China
| | - Zhi-Qiang Yang
- Higher Educational Key Laboratory for Nano Biomedical Technology of Fujian Province, Department of Pharmaceutical Analysis, Fujian Medical University, Fuzhou 350004, China
| | - Ming-Rui Yang
- Higher Educational Key Laboratory for Nano Biomedical Technology of Fujian Province, Department of Pharmaceutical Analysis, Fujian Medical University, Fuzhou 350004, China
| | - Tian-Shui Chen
- Higher Educational Key Laboratory for Nano Biomedical Technology of Fujian Province, Department of Pharmaceutical Analysis, Fujian Medical University, Fuzhou 350004, China
| | - Shurong Tang
- Higher Educational Key Laboratory for Nano Biomedical Technology of Fujian Province, Department of Pharmaceutical Analysis, Fujian Medical University, Fuzhou 350004, China
| | - Wei-Ming Sun
- Higher Educational Key Laboratory for Nano Biomedical Technology of Fujian Province, Department of Pharmaceutical Analysis, Fujian Medical University, Fuzhou 350004, China
| | - Qiaofeng Yao
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Key Laboratory of Organic Integrated Circuits, Ministry of Education, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
| | - Hao-Hua Deng
- Higher Educational Key Laboratory for Nano Biomedical Technology of Fujian Province, Department of Pharmaceutical Analysis, Fujian Medical University, Fuzhou 350004, China
| | - Wei Chen
- Higher Educational Key Laboratory for Nano Biomedical Technology of Fujian Province, Department of Pharmaceutical Analysis, Fujian Medical University, Fuzhou 350004, China
| | - Jianping Xie
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore
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28
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Zhang X, Cheng S, Chen C, Wen X, Miao J, Zhou B, Long M, Zhang L. Keto-anthraquinone covalent organic framework for H 2O 2 photosynthesis with oxygen and alkaline water. Nat Commun 2024; 15:2649. [PMID: 38531862 DOI: 10.1038/s41467-024-47023-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 03/18/2024] [Indexed: 03/28/2024] Open
Abstract
Hydrogen peroxide photosynthesis suffers from insufficient catalytic activity due to the high energy barrier of hydrogen extraction from H2O. Herein, we report that mechanochemically synthesized keto-form anthraquinone covalent organic framework which is able to directly synthesize H2O2 (4784 μmol h-1 g-1 at λ > 400 nm) from oxygen and alkaline water (pH = 13) in the absence of any sacrificial reagents. The strong alkalinity resulted in the formation of OH-(H2O)n clusters in water, which were adsorbed on keto moieties within the framework and then dissociated into O2 and active hydrogen, because the energy barrier of hydrogen extraction was largely lowered. The produced hydrogen reacted with anthraquinone to generate anthrahydroquinone, which was subsequently oxidized by O2 to produce H2O2. This study ultimately sheds light on the importance of hydrogen extraction from H2O for H2O2 photosynthesis and demonstrates that H2O2 synthesis is achievable under alkaline conditions.
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Affiliation(s)
- Xiangcheng Zhang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Silian Cheng
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Chao Chen
- School of Ecological and Environmental Science, Key Laboratory for Urban Ecological Processes and Eco-Restoration, East China Normal University, Shanghai, 200241, China
| | - Xue Wen
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jie Miao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Baoxue Zhou
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Mingce Long
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Lizhi Zhang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
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29
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Kang XW, Wang K, Zhang X, Zhong D, Ding B. Elementary Reactions in the Functional Triads of the Blue-Light Photoreceptor BLUF Domain. J Phys Chem B 2024; 128:2065-2075. [PMID: 38391132 DOI: 10.1021/acs.jpcb.3c07988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
The blue light using the flavin (BLUF) domain is one of the smallest photoreceptors in nature, which consists of a unique bidirectional electron-coupled proton relay process in its photoactivation reaction cycle. This perspective summarizes our recent efforts in dissecting the photocycle into three elementary processes, including proton-coupled electron transfer (PCET), proton rocking, and proton relay. Using ultrafast spectroscopy, we have determined the temporal sequence, rates, kinetic isotope effects (KIEs), and concertedness of these elementary steps. Our findings provide important implications for illuminating the photoactivation mechanism of the BLUF domain and suggest an engineering platform to characterize intricate reactions involving proton motions that are ubiquitous in nonphotosensitive protein machines.
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Affiliation(s)
- Xiu-Wen Kang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Kailin Wang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xiaofan Zhang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dongping Zhong
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
- Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Programs of Chemical Physics, and Programs of Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Bei Ding
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
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30
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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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31
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Sonea A, Crudo NR, Warren JJ. Understanding the Interplay of the Brønsted Acidity of Catalyst Ancillary Groups and the Solution Components in Iron-porphyrin-Mediated Carbon Dioxide Reduction. J Am Chem Soc 2024; 146:3721-3731. [PMID: 38307036 DOI: 10.1021/jacs.3c10127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2024]
Abstract
The rapid and efficient conversion of carbon dioxide (CO2) to carbon monoxide (CO) is an ongoing challenge. Catalysts based on iron-porphyrin cores have emerged as excellent electrochemical mediators of the two proton + two electron reduction of CO2 to CO, and many of the design features that promote function are known. Of those design features, the incorporation of Brønsted acids in the second coordination sphere of the iron ion has a significant impact on catalyst turnover kinetics. The Brønsted acids are often in the form of hydroxyphenyl groups. Herein, we explore how the acidity of an ancillary 2-hydroxyphenyl group affects the performance of CO2 reduction electrocatalysts. A series of meso-5,10,15,20-tetraaryl porphyrins were prepared where only the functional group at the 5-meso position has an ionizable proton. A series of cyclic voltammetry (CV) experiments reveal that the complex with -OMe positioned para to the ionizable -OH shows the largest CO2 reduction rate constants in acetonitrile solvent. This is the least acidic -OH of the compounds surveyed. The turnover frequency of the -OMe derivative can be further improved with the addition of 4-trifluoromethylphenol to the solution. In contrast, the iron-porphyrin complex with -CF3 positioned opposite the ionizable -OH shows the smallest CO2 reduction rate constants, and its turnover frequency is less enhanced with the addition of phenols to the reaction solutions. The origin of this effect is rationalized based on kinetic isotope effect experiments and density functional calculations. We conclude that catalysts with weaker internal acids coupled with stronger external acid additives provide superior CO2 reduction kinetics.
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Affiliation(s)
- Ana Sonea
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Nicholas R Crudo
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
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32
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Jeong D, Lee Y, Lee Y, Kim K, Cho J. Synthesis, Characterization, and Reactivity of a Highly Oxidative Mononuclear Manganese(IV)-Bis(Fluoro) Complex. J Am Chem Soc 2024; 146:4172-4177. [PMID: 38311844 DOI: 10.1021/jacs.3c13324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2024]
Abstract
Recently, transition-metal terminal nonoxo complexes have shown a remarkable ability to activate and functionalize C-H bonds via proton-coupled electron transfer (PCET). Here we report the first example of a mononuclear manganese(IV) bis(fluoro) complex bearing a tetradentate pyridinophane ligand, [MnIV(TBDAP)(F)2]2+ (3), with an X-ray single crystal structure and physicochemical characterization. The manganese(IV) bis(fluoro) complex has a very high reduction potential of 1.61 V vs SCE, thereby enabling the four-electron oxidation of mesitylene to 3,5-dimethylbenzaldehyde. Kinetic studies, including the kinetic isotope effect and employment of other toluene derivatives, reveal the electron transfer (ET)-driven PCET in the C-H bond activation of mesitylene by 3. This novel metal halide intermediate would be prominently valuable for expanding transition-metal halide chemistry.
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Affiliation(s)
- Donghyun Jeong
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Yujeong Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Yuri Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Kyungmin Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Jaeheung Cho
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Graduate School of Carbon Neutrality, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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33
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Sinhababu S, Singh RP, Radzhabov MR, Kumawat J, Ess DH, Mankad NP. Coordination-induced O-H/N-H bond weakening by a redox non-innocent, aluminum-containing radical. Nat Commun 2024; 15:1315. [PMID: 38351122 PMCID: PMC10864259 DOI: 10.1038/s41467-024-45721-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 02/01/2024] [Indexed: 02/16/2024] Open
Abstract
Several renewable energy schemes aim to use the chemical bonds in abundant molecules like water and ammonia as energy reservoirs. Because the O-H and N-H bonds are quite strong (>100 kcal/mol), it is necessary to identify substances that dramatically weaken these bonds to facilitate proton-coupled electron transfer processes required for energy conversion. Usually this is accomplished through coordination-induced bond weakening by redox-active metals. However, coordination-induced bond weakening is difficult with earth's most abundant metal, aluminum, because of its redox inertness under mild conditions. Here, we report a system that uses aluminum with a redox non-innocent ligand to achieve significant levels of coordination-induced bond weakening of O-H and N-H bonds. The multisite proton-coupled electron transfer manifold described here points to redox non-innocent ligands as a design element to open coordination-induced bond weakening chemistry to more elements in the periodic table.
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Affiliation(s)
- Soumen Sinhababu
- Department of Chemistry, University of Illinois Chicago, Chicago, IL, 60607, USA
| | | | - Maxim R Radzhabov
- Department of Chemistry, University of Illinois Chicago, Chicago, IL, 60607, USA
| | - Jugal Kumawat
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, 84604, UT, USA
| | - Daniel H Ess
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, 84604, UT, USA
| | - Neal P Mankad
- Department of Chemistry, University of Illinois Chicago, Chicago, IL, 60607, USA.
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34
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Tepaske MA, Fitterer A, Verplancke H, Delony D, Neben MC, de Bruin B, Holthausen MC, Schneider S. C-H Bond Activation by Iridium(III) and Iridium(IV) Oxo Complexes. Angew Chem Int Ed Engl 2024; 63:e202316729. [PMID: 38116899 DOI: 10.1002/anie.202316729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 12/18/2023] [Accepted: 12/19/2023] [Indexed: 12/21/2023]
Abstract
Oxidation of an iridium(III) oxo precursor enabled the structural, spectroscopic, and quantum-chemical characterization of the first well-defined iridium(IV) oxo complex. Side-by-side examination of the proton-coupled electron transfer thermochemistry revealed similar driving forces for the isostructural oxo complexes in two redox states due to compensating contributions from H+ and e- transfer. However, C-H activation of dihydroanthracene revealed significant hydrogen tunneling for the distinctly more basic iridium(III) oxo complex. Our findings complement the growing body of data that relate tunneling to ground state properties as predictors for the selectivity of C-H bond activation.
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Affiliation(s)
- Martijn A Tepaske
- Georg-August-Universität, Institut für Anorganische Chemie, Tammanstraβe 4, 37077, Göttingen, Germany
| | - Arnd Fitterer
- Institut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Straβe 7, 60438, Frankfurt am Main, Germany
| | - Hendrik Verplancke
- Institut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Straβe 7, 60438, Frankfurt am Main, Germany
| | - Daniel Delony
- Georg-August-Universität, Institut für Anorganische Chemie, Tammanstraβe 4, 37077, Göttingen, Germany
| | - Marc C Neben
- Georg-August-Universität, Institut für Anorganische Chemie, Tammanstraβe 4, 37077, Göttingen, Germany
| | - Bas de Bruin
- Homogeneous, Supramolecular and Bio-Inspired Catalysis Group, van't Hoff Institute for Molecular Sciences (HIMS), Science Park 904, 1098XH, Amsterdam, The Netherlands
| | - Max C Holthausen
- Institut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Straβe 7, 60438, Frankfurt am Main, Germany
| | - Sven Schneider
- Georg-August-Universität, Institut für Anorganische Chemie, Tammanstraβe 4, 37077, Göttingen, Germany
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35
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Oloyede UN, Flowers RA. Coordination-induced bond weakening and small molecule activation by low-valent titanium complexes. Dalton Trans 2024; 53:2413-2441. [PMID: 38224159 DOI: 10.1039/d3dt03454b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Bond activation of small molecules through coordination to low valent metal complexes in M⋯X-H type interactions (where X = O, N, B, Si, etc.) leads to the formation of unusually weak X-H bonds and provides a powerful approach for the synthesis of target compounds under very mild conditions. Coordination of small molecules like water, amides, silanes, boranes, and dinitrogen to Ti(III) or Ti(II) complexes results in the synergetic redistribution of electrons between the metal orbitals and the ligand orbitals which weakens and enables the facile cleavage of the X-H or N-N bonds of the ligands. This review presents an overview of coordination-induced bond activation of small molecules by low valent titanium complexes. In particular, the applications of low valent titanium-induced bond weakening in nitrogen fixation are presented. The review concludes with potential future directions for work in this area including low-valent Ti-based PCET systems, photocatalytic nitrogen reduction, and approaches to tailoring complexes for optimal bond activation.
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Affiliation(s)
| | - Robert A Flowers
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
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36
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Cooney S, Walls MRA, Schreiber E, Brennessel WW, Matson EM. Heterometal Dopant Changes the Mechanism of Proton-Coupled Electron Transfer at the Polyoxovanadate-Alkoxide Surface. J Am Chem Soc 2024; 146:2364-2369. [PMID: 38241170 PMCID: PMC10835708 DOI: 10.1021/jacs.3c14054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/21/2024]
Abstract
The transfer of two H-atom equivalents to the titanium-doped polyoxovanadate-alkoxide, [TiV5O6(OCH3)13], results in the formation of a V(III)-OH2 site at the surface of the assembly. Incorporation of the group (IV) metal ion results in a weakening of the O-H bonds of [TiV5O5(OH2)(OCH3)13] in comparison to its homometallic congener, [V6O6(OH2)(OCH3)12], resembling more closely the thermodynamics reported for the one-electron reduced derivative, [V6O6(OH2)(OCH3)12]1-. An analysis of early time points of the reaction of [TiV5O6(OCH3)13] and 5,10-dihydrophenazine reveals the formation of an oxidized substrate, suggesting that proton-coupled electron transfer proceeds via initial electron transfer from substrate to cluster prior to proton transfer. These results demonstrate the profound influence of heterometal dopants on the mechanism of PCET with respect to the surface of the assembly.
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Affiliation(s)
- Shannon
E. Cooney
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - M. Rebecca A. Walls
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Eric Schreiber
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - William W. Brennessel
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Ellen M. Matson
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
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37
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Doyle L, Magherusan A, Xu S, Murphy K, Farquhar ER, Molton F, Duboc C, Que L, McDonald AR. Class Ib Ribonucleotide Reductases: Activation of a Peroxido-Mn IIMn III to Generate a Reactive Oxo-Mn IIIMn IV Oxidant. Inorg Chem 2024; 63:2194-2203. [PMID: 38231137 PMCID: PMC10828993 DOI: 10.1021/acs.inorgchem.3c04163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/18/2023] [Accepted: 12/22/2023] [Indexed: 01/18/2024]
Abstract
In the postulated catalytic cycle of class Ib Mn2 ribonucleotide reductases (RNRs), a MnII2 core is suggested to react with superoxide (O2·-) to generate peroxido-MnIIMnIII and oxo-MnIIIMnIV entities prior to proton-coupled electron transfer (PCET) oxidation of tyrosine. There is limited experimental support for this mechanism. We demonstrate that [MnII2(BPMP)(OAc)2](ClO4) (1, HBPMP = 2,6-bis[(bis(2 pyridylmethyl)amino)methyl]-4-methylphenol) was converted to peroxido-MnIIMnIII (2) in the presence of superoxide anion that converted to (μ-O)(μ-OH)MnIIIMnIV (3) via the addition of an H+-donor (p-TsOH) or (μ-O)2MnIIIMnIV (4) upon warming to room temperature. The physical properties of 3 and 4 were probed using UV-vis, EPR, X-ray absorption, and IR spectroscopies and mass spectrometry. Compounds 3 and 4 were capable of phenol oxidation to yield a phenoxyl radical via a concerted PCET oxidation, supporting the proposed mechanism of tyrosyl radical cofactor generation in RNRs. The synthetic models demonstrate that the postulated O2/Mn2/tyrosine activation mechanism in class Ib Mn2 RNRs is plausible and provides spectral insights into intermediates currently elusive in the native enzyme.
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Affiliation(s)
- Lorna Doyle
- School
of Chemistry, Trinity College Dublin, The
University of Dublin, College Green, Dublin 2, Ireland
| | - Adriana Magherusan
- School
of Chemistry, Trinity College Dublin, The
University of Dublin, College Green, Dublin 2, Ireland
| | - Shuangning Xu
- Department
of Chemistry and Centre for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Kayleigh Murphy
- School
of Chemistry, Trinity College Dublin, The
University of Dublin, College Green, Dublin 2, Ireland
| | - Erik R. Farquhar
- Case
Western Reserve University Center for Synchrotron Biosciences, National
Synchrotron Light Source II, Brookhaven
National Laboratory Upton, New
York 11973, United States
| | - Florian Molton
- CNRS
UMR 5250, DCM, Univ. Grenoble Alpes, Grenoble F-38000, France
| | - Carole Duboc
- CNRS
UMR 5250, DCM, Univ. Grenoble Alpes, Grenoble F-38000, France
| | - Lawrence Que
- Department
of Chemistry and Centre for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Aidan R. McDonald
- School
of Chemistry, Trinity College Dublin, The
University of Dublin, College Green, Dublin 2, Ireland
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38
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Chatgilialoglu C, Barata-Vallejo S, Gimisis T. Radical Reactions in Organic Synthesis: Exploring in-, on-, and with-Water Methods. Molecules 2024; 29:569. [PMID: 38338314 PMCID: PMC10856544 DOI: 10.3390/molecules29030569] [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: 12/19/2023] [Revised: 01/18/2024] [Accepted: 01/19/2024] [Indexed: 02/12/2024] Open
Abstract
Radical reactions in water or aqueous media are important for organic synthesis, realizing high-yielding processes under non-toxic and environmentally friendly conditions. This overview includes (i) a general introduction to organic chemistry in water and aqueous media, (ii) synthetic approaches in, on, and with water as well as in heterogeneous phases, (iii) reactions of carbon-centered radicals with water (or deuterium oxide) activated through coordination with various Lewis acids, (iv) photocatalysis in water and aqueous media, and (v) synthetic applications bioinspired by naturally occurring processes. A wide range of chemical processes and synthetic strategies under different experimental conditions have been reviewed that lead to important functional group translocation and transformation reactions, leading to the preparation of complex molecules. These results reveal how water as a solvent/medium/reagent in radical chemistry has matured over the last two decades, with further discoveries anticipated in the near future.
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Affiliation(s)
- Chryssostomos Chatgilialoglu
- Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, 40129 Bologna, Italy
- Center of Advanced Technologies, Adam Mickiewicz University, 61-712 Poznan, Poland
| | - Sebastian Barata-Vallejo
- Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, 40129 Bologna, Italy
- Facultad de Farmacia y Bioquímica, Departamento de Ciencias Químicas, Universidad de Buenos Aires, Junin 954, Buenos Aires CP 1113, Argentina
| | - Thanasis Gimisis
- Department of Chemistry, National and Kapodistrian University of Athens, 15771 Athens, Greece
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39
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Galvin CM, Marron DP, Dressel JM, Waymouth RM. Coordination-Induced Bond Weakening and Electrocatalytic Proton-Coupled Electron Transfer of a Ruthenium Verdazyl Complex. Inorg Chem 2024; 63:954-960. [PMID: 38153690 DOI: 10.1021/acs.inorgchem.3c02775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Coordination of the leucoverdazyl ligand 2,4-diisopropyl-6-(pyridin-2-yl)-1,4-dihydro-1,2,4,5-tetrazin-3(2H)-one VdH to Ru significantly weakens the ligand's N-H bond. Electrochemical measurements show that the metalated leucoverdazyl Ru(VdH)(acetylacetonate)2 RuVdH has a lower pKa (-5 units), BDFE (-7 kcal/mol), and hydricity (-22 kcal/mol) than the free ligand. DFT calculations suggest that the increased acidity is in part attributable to stabilization of the conjugate base Vd-. When free, Vd- distorts to avoid an 8πe- antiaromatic state, but it remains planar when bound to Ru. Proton-coupled electron transfer (PCET) behavior is observed for both the free and metalated leucoverdazyls. PCET equilibrium between the Vd radical and TEMPOH affords a VdH BDFE that is in good agreement with that obtained from electrochemical methods. RuVd exhibits electrocatalytic PCET donor behavior. Under acidic conditions, it reduces the persistent trityl radical ·CAr3 (Ar = p-tert-butylphenyl) to the corresponding triarylmethane HCAr3 via net 1e-/1H+ transfer from RuVdH.
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Affiliation(s)
- Conor M Galvin
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Daniel P Marron
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Julia M Dressel
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Robert M Waymouth
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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40
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Gutiérrez-Blanco M, Algarra AG, Guillamón E, Fernández-Trujillo MJ, Oliva M, Basallote MG, Llusar R, Safont VS. Spin-Crossing in the ( Z)-Selective Alkyne Semihydrogenation Mechanism Catalyzed by Mo 3S 4 Clusters: A Density Functional Theory Exploration. Inorg Chem 2024; 63:1000-1009. [PMID: 38173271 DOI: 10.1021/acs.inorgchem.3c03057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Semihydrogenation of internal alkynes catalyzed by the air-stable imidazolyl amino [Mo3S4Cl3(ImNH2)3]+ cluster selectively affords the (Z)-alkene under soft conditions in excellent yields. Experimental results suggest a sulfur-based mechanism with the formation of a dithiolene adduct through interaction of the alkyne with the bridging sulfur atoms. However, computational studies indicate that this mechanism is unable to explain the experimental outcome: mild reaction conditions, excellent selectivity toward the (Z)-isomer, and complete deuteration of the vinylic positions in the presence of CD3OD and CH3OD. An alternative mechanism that explains the experimental results is proposed. The reaction begins with the hydrogenation of two of the Mo3(μ3-S)(μ-S)3 bridging sulfurs to yield a bis(hydrosulfide) intermediate that performs two sequential hydrogen atom transfers (HAT) from the S-H groups to the alkyne. The first HAT occurs with a spin change from singlet to triplet. After the second HAT, the singlet state is recovered. Although the dithiolene adduct is more stable than the hydrosulfide species, the large energy required for the subsequent H2 addition makes the system evolve via the second alternative pathway to selectively render the (Z)-alkene with a lower overall activation barrier.
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Affiliation(s)
- María Gutiérrez-Blanco
- Departament de Química Física i Analítica, Universitat Jaume I, Av. Sos Baynat s/n, Castelló 12071, Spain
| | - Andrés G Algarra
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Instituto de Biomoléculas (INBIO), Facultad de Ciencias, Universidad de Cádiz, Apartado 40, Puerto Real, Cádiz 11510, Spain
| | - Eva Guillamón
- Departament de Química Física i Analítica, Universitat Jaume I, Av. Sos Baynat s/n, Castelló 12071, Spain
| | - M Jesús Fernández-Trujillo
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Instituto de Biomoléculas (INBIO), Facultad de Ciencias, Universidad de Cádiz, Apartado 40, Puerto Real, Cádiz 11510, Spain
| | - Mónica Oliva
- Departament de Química Física i Analítica, Universitat Jaume I, Av. Sos Baynat s/n, Castelló 12071, Spain
| | - Manuel G Basallote
- Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Instituto de Biomoléculas (INBIO), Facultad de Ciencias, Universidad de Cádiz, Apartado 40, Puerto Real, Cádiz 11510, Spain
| | - Rosa Llusar
- Departament de Química Física i Analítica, Universitat Jaume I, Av. Sos Baynat s/n, Castelló 12071, Spain
| | - Vicent S Safont
- Departament de Química Física i Analítica, Universitat Jaume I, Av. Sos Baynat s/n, Castelló 12071, Spain
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41
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Groff BD, Koronkiewicz B, Mayer JM. Polar Effects in Hydrogen Atom Transfer Reactions from a Proton-Coupled Electron Transfer (PCET) Perspective: Abstractions from Toluenes. J Org Chem 2023; 88:16259-16269. [PMID: 37978890 PMCID: PMC10841608 DOI: 10.1021/acs.joc.3c01748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Rate constants for hydrogen atom transfer (HAT) reactions of substituted toluenes with tert-butyl, tert-butoxy, and tert-butylperoxyl radicals are reanalyzed here using the free energies of related proton transfer (PT) and electron transfer (ET) reactions, calculated from an extensive set of compiled or estimated pKa and E° values. The Eyring activation energies ΔGHAT‡ do not correlate with the relatively constant ΔG°HAT, but do correlate close-to-linearly with ΔG°PT and ΔG°ET. The slopes of correlations are similar for the three radicals except that the tBu• barriers shift in the opposite direction from the oxyl radical barriers─a clear example of the qualitative "polar effect" in HAT reactions. When cast quantitatively in free energy terms (ΔGHAT‡ vs ΔG°PT/ET), this effect is very small, only 5-10% of the typical Bell-Evans-Polanyi (BEP) effect of changing ΔG°HAT. This analysis also highlights connections between polar effects and the concepts of "asynchronous" or "imbalanced" HAT reactions in which the PT and ET components of ΔG°HAT contribute differently to the barrier. Finally, these observations are discussed in light of the traditional explanations of polar effects and the potential for a rubric that could predict the extent to which contra-thermodynamic selectivity may be achieved in HAT reactions.
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Affiliation(s)
- Benjamin D. Groff
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Brian Koronkiewicz
- Current Address: Johns Hopkins University Applied Physics Laboratory, 11091 Johns Hopkins Rd, Laurel, MD 20723
| | - James M. Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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42
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Latrache M, Lefebvre C, Abe M, Hoffmann N. Photochemically Induced Hydrogen Atom Transfer and Intramolecular Radical Cyclization Reactions with Oxazolones. J Org Chem 2023; 88:16435-16455. [PMID: 37983612 DOI: 10.1021/acs.joc.3c01951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Photochemically induced intramolecular hydrogen atom transfer in oxazolones is reported. An acetal or thioacetal function at the side chain acts as a hydrogen donor while the photochemical exited oxazolone is the acceptor. A one-step process─the electron and the proton are simultaneously transferred─is productive, while electron transfer followed by proton transfer is inefficient. Radical combination then takes place, leading to the formation of a C-C or C-N bond. The regioselectivity of the reaction is explained by the diradical/zwitterion dichotomy of radical intermediates at the singlet state. In the present case, the zwitterion structure plays a central role, and intramolecular electron transfer favors spin-orbit coupling and thus the intersystem crossing to the singlet state. The reaction of corresponding thioacetal derivatives is less efficient. In this case, photochemical electron transfer is competitive. The photoproducts resulting from C-C bond formation easily undergo stepwise thermal decarboxylation in which zwitterionic and polar transition states are involved. A computational study of this step has also been performed.
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Affiliation(s)
- Mohammed Latrache
- ICMR, Equipe de Photochimie, CNRS, Université de Reims Champagne-Ardenne, UFR Sciences, B.P. 1039, Reims 51687 France
| | - Corentin Lefebvre
- ICMR, Equipe de Photochimie, CNRS, Université de Reims Champagne-Ardenne, UFR Sciences, B.P. 1039, Reims 51687 France
| | - Manabu Abe
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
- Hiroshima Research Center for Photo-Drug-Delivery Systems (Hi-P-DDS), 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Norbert Hoffmann
- ICMR, Equipe de Photochimie, CNRS, Université de Reims Champagne-Ardenne, UFR Sciences, B.P. 1039, Reims 51687 France
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43
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Gobbato T, Volpato GA, Sartorel A, Bonchio M. A breath of sunshine: oxygenic photosynthesis by functional molecular architectures. Chem Sci 2023; 14:12402-12429. [PMID: 38020375 PMCID: PMC10646967 DOI: 10.1039/d3sc03780k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 09/28/2023] [Indexed: 12/01/2023] Open
Abstract
The conversion of light into chemical energy is the game-changer enabling technology for the energetic transition to renewable and clean solar fuels. The photochemistry of interest includes the overall reductive/oxidative splitting of water into hydrogen and oxygen and alternatives based on the reductive conversion of carbon dioxide or nitrogen, as primary sources of energy-rich products. Devices capable of performing such transformations are based on the integration of three sequential core functions: light absorption, photo-induced charge separation, and the photo-activated breaking/making of molecular bonds via specific catalytic routes. The key to success does not rely simply on the individual components' performance, but on their optimized integration in terms of type, number, geometry, spacing, and linkers dictating the photosynthetic architecture. Natural photosynthesis has evolved along this concept, by integrating each functional component in one specialized "body" (from the Greek word "soma") to enable the conversion of light quanta with high efficiency. Therefore, the natural "quantasome" represents the key paradigm to inspire man-made constructs for artificial photosynthesis. The case study presented in this perspective article deals with the design of artificial photosynthetic systems for water oxidation and oxygen production, engineered as molecular architectures then rendered on electrodic surfaces. Water oxidation to oxygen is indeed the pervasive oxidative reaction used by photosynthetic organisms, as the source of reducing equivalents (electrons and protons) to be delivered for the processing of high-energy products. Considering the vast and abundant supply of water (including seawater) as a renewable source on our planet, this is also a very appealing option for photosynthetic energy devices. We will showcase the progress in the last 15 years (2009-2023) in the strategies for integrating functional building blocks as molecular photosensitizers, multi-redox water oxidation catalysts and semiconductor materials, highlighting how additional components such as redox mediators, hydrophilic/hydrophobic pendants, and protective layers can impact on the overall photosynthetic performance. Emerging directions consider the modular tuning of the multi-component device, in order to target a diversity of photocatalytic oxidations, expanding the scope of the primary electron and proton sources while enhancing the added-value of the oxidation product beyond oxygen: the selective photooxidation of organics combines the green chemistry vision with renewable energy schemes and is expected to explode in coming years.
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Affiliation(s)
- Thomas Gobbato
- Department of Chemical Sciences, University of Padova via Marzolo 1 35131 Padova Italy
| | - Giulia Alice Volpato
- Department of Chemical Sciences, University of Padova via Marzolo 1 35131 Padova Italy
| | - Andrea Sartorel
- Department of Chemical Sciences, University of Padova via Marzolo 1 35131 Padova Italy
| | - Marcella Bonchio
- Department of Chemical Sciences, University of Padova via Marzolo 1 35131 Padova Italy
- ITM-CNR Section of Padova, INSTM Unit of Padova via Marzolo 1 35131 Padova Italy
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44
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Lan H, Wang L, He R, Huang S, Yu J, Guo J, Luo J, Li Y, Zhang J, Lin J, Zhang S, Zeng M, Fu L. 2D quasi-layered material with domino structure. Nat Commun 2023; 14:7225. [PMID: 37940641 PMCID: PMC10632391 DOI: 10.1038/s41467-023-42818-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 10/23/2023] [Indexed: 11/10/2023] Open
Abstract
Interlayer coupling strength dichotomizes two-dimensional (2D) materials into layered and non-layered types. Traditionally, they can be regarded as atomic layers intrinsically linked via van der Waals (vdW) forces or covalent bonds, oriented orthogonally to their growth plane. In our work, we report a material system that differentiates from layered and non-layered materials, termed quasi-layered domino-structured (QLDS) materials, effectively bridging the gap between these two typical categories. Considering the skewed structure, the force orthogonal to the 2D QLDS-GaTe growth plane constitutes a synergistic blend of vdW forces and covalent bonds, with neither of them being perpendicular to the 2D growth plane. This unique amalgamation results in a force that surpasses that in layered materials, yet is weaker than that in non-layered materials. Therefore, the lattice constant contraction along this unique orientation can be as much as 7.7%, tantalizingly close to the theoretical prediction of 10.8%. Meanwhile, this feature endows remarkable anisotropy, second harmonic generation enhancement with a staggering susceptibility of 394.3 pm V-1. These findings endow further applications arranged in nonlinear optics, sensors, and catalysis.
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Affiliation(s)
- Haihui Lan
- The Institute for Advanced Studies, Wuhan University, 430072, Wuhan, China
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Luyang Wang
- College of Chemistry and Molecular Sciences, Wuhan University, 430072, Wuhan, China
| | - Runze He
- The Institute for Advanced Studies, Wuhan University, 430072, Wuhan, China
| | - Shuyi Huang
- College of Chemistry and Molecular Sciences, Wuhan University, 430072, Wuhan, China
| | - Jinqiu Yu
- College of Chemistry and Molecular Sciences, Wuhan University, 430072, Wuhan, China
| | - Jinming Guo
- Key Laboratory of Green Preparation and Application for Functional Materials, Ministry of Education, School of Materials Science and Engineering, Hubei University, 430062, Wuhan, China
| | - Jingrui Luo
- College of Chemistry and Molecular Sciences, Wuhan University, 430072, Wuhan, China
| | - Yiling Li
- College of Chemistry and Molecular Sciences, Wuhan University, 430072, Wuhan, China
| | - Jinyang Zhang
- Key Laboratory of Green Preparation and Application for Functional Materials, Ministry of Education, School of Materials Science and Engineering, Hubei University, 430062, Wuhan, China
| | - Jiaxin Lin
- School of Physics and Technology, Wuhan University, 430072, Wuhan, China
| | - Shunping Zhang
- School of Physics and Technology, Wuhan University, 430072, Wuhan, China
| | - Mengqi Zeng
- College of Chemistry and Molecular Sciences, Wuhan University, 430072, Wuhan, China.
| | - Lei Fu
- The Institute for Advanced Studies, Wuhan University, 430072, Wuhan, China.
- College of Chemistry and Molecular Sciences, Wuhan University, 430072, Wuhan, China.
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45
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Peter CYM, Schreiber E, Proe KR, Matson EM. Surface ligand length influences kinetics of H-atom uptake in polyoxovanadate-alkoxide clusters. Dalton Trans 2023; 52:15775-15785. [PMID: 37850536 DOI: 10.1039/d3dt02074f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2023]
Abstract
The uptake of hydrogen atoms (H-atoms) at reducible metal oxide nanocrystal surfaces has implications in catalysis and energy storage. However, it is often difficult to gain insight into the physicochemical factors that dictate the thermodynamics and kinetics of H-atom transfer to the surface of these assemblies. Recently, our research group has demonstrated the formation of oxygen-atom (O-atom) defects in polyoxovanadate-alkoxide (POV-alkoxide) clusters via conversion of surface oxido moieties to aquo ligands, which can be accomplished via addition of two H-atom equivalents. Here, we present the dependence of O-atom defect formation via H-atom transfer at the surface of vanadium oxide clusters on the length of surface alkoxide ligands. Analysis of H-atom transfer reactions to low-valent POV-alkoxide clusters [V6O7(OR)12]1- (R = Me, Et, nPr, nBu) reveals that the length of primary alkoxide surface ligands does not significantly influence the thermodynamics of these processes. However, surface ligand length has a significant impact on the kinetics of these PCET reactions. Indeed, the methoxide-bridged cluster, [V6O7(OMe)12]1- reacts ∼20 times faster than the other derivatives evaluated. Interestingly, as the aliphatic linkages are increased in size from -C2H5 to -C4H9, reaction rates remain consistent, suggesting restricted access to available ligand conformers as a result of the incompatibility of the aliphatic ligands and acetonitrile may buffer further changes to the rate of reaction.
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Affiliation(s)
- Chari Y M Peter
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
| | - Eric Schreiber
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
| | - Kathryn R Proe
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
| | - Ellen M Matson
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
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46
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Schneider JE, Anderson JS. Reconciling Imbalanced and Nonadiabatic Reactivity in Transition Metal-Oxo-Mediated Concerted Proton Electron Transfer (CPET). J Phys Chem Lett 2023; 14:9548-9555. [PMID: 37856336 DOI: 10.1021/acs.jpclett.3c02318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Recently, there have been several experimental demonstrations of how the rates of concerted proton electron transfer (CPET) are affected by stepwise thermodynamic parameters of only proton (ΔG°PT) or electron (ΔG°ET) transfer. Semiclassical structure-activity relationships have been invoked to rationalize these linear free energy relationships, but it is not clear how they would manifest in a nonadiabatic reaction. Using density functional theory calculations, we demonstrate how a decrease in ΔG°PT can lead to transition state imbalance in a nonadiabatic framework. We then use these calculations to anchor a theoretical model that reproduces experimental trends with ΔG°PT and ΔG°ET. Our results reconcile predictions from semiclassical transition state theory with models that treat proton transfer quantum mechanically in CPET reactivity, make new predictions about the importance of basicity for uphill CPET reactions, and suggest similar treatments may be possible for other nonadiabatic reactions.
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Affiliation(s)
- Joseph E Schneider
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - John S Anderson
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
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Depenbrock F, Limpke T, Bill E, SantaLucia DJ, van Gastel M, Walleck S, Oldengott J, Stammler A, Bögge H, Glaser T. Reactivities and Electronic Structures of μ-1,2-Peroxo and μ-1,2-Superoxo Co IIICo III Complexes: Electrophilic Reactivity and O 2 Release Induced by Oxidation. Inorg Chem 2023; 62:17913-17930. [PMID: 37838986 DOI: 10.1021/acs.inorgchem.3c02782] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2023]
Abstract
Peroxo complexes are key intermediates in water oxidation catalysis (WOC). Cobalt plays an important role in WOC, either as oxides CoOx or as {CoIII(μ-1,2-peroxo)CoIII} complexes, which are the oldest peroxo complexes known. The oxidation of {CoIII(μ-1,2-peroxo)CoIII} complexes had usually been described to form {CoIII(μ-1,2-superoxo)CoIII} complexes; however, recently the formation of {CoIV(μ-1,2-peroxo)CoIII} species were suggested. Using a bis(tetradentate) dinucleating ligand, we present here the synthesis and characterization of {CoIII(μ-1,2-peroxo)(μ-OH)CoIII} and {CoIII(μ-OH)2CoIII} complexes. Oxidation of {CoIII(μ-1,2-peroxo)(μ-OH)CoIII} at -40 °C in CH3CN provides the stable {CoIII(μ-1,2-superoxo)(μ-OH)CoIII} species and activates electrophilic reactivity. Moreover, {CoIII(μ-1,2-peroxo)(μ-OH)CoIII} catalyzes water oxidation, not molecularly but rather via CoOx films. While {CoIII(μ-1,2-peroxo)(μ-OH)CoIII} can be reversibly deprotonated with DBU at -40 °C in CH3CN, {CoIII(μ-1,2-superoxo)(μ-OH)CoIII} undergoes irreversible conversions upon reaction with bases to a new intermediate that is also the decay product of {CoIII(μ-1,2-superoxo)(μ-OH)CoIII} in aqueous solution at pH > 2. Based on a combination of experimental methods, the new intermediate is proposed to have a {CoII(μ-OH)CoIII} core formed by the release of O2 from {CoIII(μ-1,2-superoxo)(μ-OH)CoIII} confirmed by a 100% yield of O2 upon photocatalytic oxidation of {CoIII(μ-1,2-peroxo)(μ-OH)CoIII}. This release of O2 by oxidation of a peroxo intermediate corresponds to the last step in molecular WOC.
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Affiliation(s)
- Felix Depenbrock
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Thomas Limpke
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstr. 34-36, Mülheim an der Ruhr D-45470, Germany
| | - Daniel J SantaLucia
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr D-45470, Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr D-45470, Germany
| | - Stephan Walleck
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Jan Oldengott
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Anja Stammler
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Hartmut Bögge
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Thorsten Glaser
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
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48
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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: 0] [Impact Index Per Article: 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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Hashemi A, Khakpour R, Mahdian A, Busch M, Peljo P, Laasonen K. Density functional theory and machine learning for electrochemical square-scheme prediction: an application to quinone-type molecules relevant to redox flow batteries. DIGITAL DISCOVERY 2023; 2:1565-1576. [PMID: 38013904 PMCID: PMC10561546 DOI: 10.1039/d3dd00091e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 09/11/2023] [Indexed: 11/29/2023]
Abstract
Proton-electron transfer (PET) reactions are rather common in chemistry and crucial in energy storage applications. How electrons and protons are involved or which mechanism dominates is strongly molecule and pH dependent. Quantum chemical methods can be used to assess redox potential (Ered.) and acidity constant (pKa) values but the computations are rather time consuming. In this work, supervised machine learning (ML) models are used to predict PET reactions and analyze molecular space. The data for ML have been created by density functional theory (DFT) calculations. Random forest regression models are trained and tested on a dataset that we created. The dataset contains more than 8200 quinone-type organic molecules that each underwent two proton and two electron transfer reactions. Both structural and chemical descriptors are used. The HOMO of the reactant and LUMO of the product participating in the oxidation reaction appeared to be strongly associated with Ered.. Trained models using a SMILES-based structural descriptor can efficiently predict the pKa and Ered. with a mean absolute error of less than 1 and 66 mV, respectively. Good prediction accuracy of R2 > 0.76 and >0.90 was also obtained on the external test set for Ered. and pKa, respectively. This hybrid DFT-ML study can be applied to speed up the screening of quinone-type molecules for energy storage and other applications.
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Affiliation(s)
- Arsalan Hashemi
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
| | - Reza Khakpour
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
| | - Amir Mahdian
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
| | - Michael Busch
- Institute of Theoretical Chemistry, Ulm University Albert-Einstein Allee 11 89069 Ulm Germany
| | - Pekka Peljo
- Research Group of Battery Materials and Technologies, Department of Mechanical and Materials Engineering, Faculty of Technology, University of Turku 20014 Turun Yliopisto Finland
| | - Kari Laasonen
- Department of Chemistry and Material Science, School of Chemical Engineering, Aalto University 02150 Espoo Finland
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Matsumoto A, Maeda N, Maruoka K. Bidirectional Elongation Strategy Using Ambiphilic Radical Linchpin for Modular Access to 1,4-Dicarbonyls via Sequential Photocatalysis. J Am Chem Soc 2023; 145:20344-20354. [PMID: 37490759 DOI: 10.1021/jacs.3c05337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023]
Abstract
Organic molecules that can be connected to multiple substrates by sequential C-C bond formations can be utilized as linchpins in multicomponent processes. While they are useful for rapidly increasing molecular complexity, most of the reported linchpin coupling methods rely on the use of organometallic species as strong carbon nucleophiles to form C-C bonds, which narrows the functional group compatibility. Here, we describe a metal-free, radical-mediated coupling approach using a formyl-stabilized phosphonium ylide as a multifunctional linchpin under visible-light photoredox conditions. The present method uses the ambiphilic character of the phosphonium ylide, which serves as both a nucleophilic and an electrophilic carbon-centered radical source. The stepwise and controllable generation of these radical intermediates allows sequential photocatalysis involving two mechanistically distinct radical additions, both of which are initiated by the same photocatalyst in one pot with high functional group tolerance. The methodology enables a bidirectional assembly of the linchpin with two electronically differentiated alkene fragments and thus offers rapid and modular access to 1,4-dicarbonyl compounds as versatile synthetic intermediates.
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Affiliation(s)
- Akira Matsumoto
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Natsumi Maeda
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Keiji Maruoka
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China
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