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Suzuki W, Mizuhata Y, Tokitoh N, Teranishi T. Dioxygen Activation by Gold(I)-Distorted Porphyrin Dinuclear Complexes. Chemistry 2024:e202401242. [PMID: 38888030 DOI: 10.1002/chem.202401242] [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: 05/26/2024] [Revised: 06/15/2024] [Accepted: 06/17/2024] [Indexed: 06/20/2024]
Abstract
Interactions between gold-based materials and dioxygen (O2) have motivated researchers to understand reaction mechanisms for O2 activation by homo- and heterogeneous gold catalysts. In this work, gold(I) porphyrin dinuclear complexes were synthesized with a saddle-distorted porphyrin ligand. The gold(I) porphyrin complexes showed unprecedented O2 activation in the presence of protic solvents to form gold(III) tetradentate porphyrin complexes. Mechanistic insights into the O2 activation by the gold(I) center were elucidated by spectroscopic measurements and theoretical calculations, revealing that dissociation of halides on the gold(I) center by alcohol solvents and hydrogen bonding of an N-H proton in the distorted porphyrin with dioxygen played important roles in establishing the unique reactivities of gold(I) complexes.
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Affiliation(s)
- Wataru Suzuki
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
- Graduate School of Engineering, University of Hyogo, 2167 Shosha Himeji, Hyogo, 671-2280, Japan
| | - Yoshiyuki Mizuhata
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
- Graduate School of Science, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
- Integrated Research Consortium on Chemical Sciences, Gokasho Uji, Kyoto, 611-0011, Japan
| | - Norihiro Tokitoh
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
- Graduate School of Science, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
- Integrated Research Consortium on Chemical Sciences, Gokasho Uji, Kyoto, 611-0011, Japan
| | - Toshiharu Teranishi
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
- Graduate School of Science, Kyoto University, Gokasho Uji, Kyoto, 611-0011, Japan
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2
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Ishizuka T, Kogawa T, Ogawa C, Kotani H, Shiota Y, Yoshizawa K, Kojima T. Enhancement of Reactivity of a Ru IV-Oxo Complex in Oxygen-Atom-Transfer Catalysis by Hydrogen-Bonding with Amide Moieties in the Second Coordination Sphere. JACS AU 2023; 3:2813-2825. [PMID: 37885582 PMCID: PMC10598587 DOI: 10.1021/jacsau.3c00377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 08/25/2023] [Accepted: 08/25/2023] [Indexed: 10/28/2023]
Abstract
We have synthesized and characterized a RuII-OH2 complex (2), which has a pentadentate ligand with two pivalamide groups as bulky hydrogen-bonding (HB) moieties in the second coordination sphere (SCS). Complex 2 exhibits a coordination equilibrium through the coordination of one of the pivalamide oxygens to the Ru center in water, affording a η6-coordinated complex, 3. A detailed thermodynamic analysis of the coordination equilibrium revealed that the formation of 3 from 2 is entropy-driven owing to the dissociation of the axial aqua ligand in 2. Complex 2 was oxidized by a CeIV salt to produce the corresponding RuIII(OH) complex (5), which was characterized crystallographically. In the crystal structure of 5, hydrogen bonds are formed among the NH groups of the pivalamide moieties and the oxygen atom of the hydroxo ligand. Further 1e--oxidation of 5 yields the corresponding RuIV(O) complex, 6, which has intramolecular HB of the oxo ligand with two amide N-H protons. Additionally, the RuIII(OH) complex, 5, exhibits disproportionation to the corresponding RuIV(O) complex, 6, and a mixture of the RuII complexes, 2 and 3, in an acidic aqueous solution. We investigated the oxidation of a phenol derivative using complex 6 as the active species and clarified the switch of the reaction mechanism from hydrogen-atom transfer at pH 2.5 to electron transfer, followed by proton transfer at pH 1.0. Additionally, the intramolecular HB in 6 exerts enhancing effects on oxygen-atom transfer reactions from 6 to alkenes such as cyclohexene and its water-soluble derivative to afford the corresponding epoxides, relative to the corresponding RuIV(O) complex (6') lacking the HB moieties in the SCS.
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Affiliation(s)
- Tomoya Ishizuka
- Department
of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Taichi Kogawa
- Department
of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Chisato Ogawa
- Department
of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Hiroaki Kotani
- Department
of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Yoshihito Shiota
- Institute
for Materials Chemistry and Engineering, Kyushu University, Moto-oka, Nishi-Ku, Fukuoka 819-0395, Japan
| | - Kazunari Yoshizawa
- Institute
for Materials Chemistry and Engineering, Kyushu University, Moto-oka, Nishi-Ku, Fukuoka 819-0395, Japan
| | - Takahiko Kojima
- Department
of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
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3
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Zhao N, Goetz MK, Schneider JE, Anderson JS. Testing the Limits of Imbalanced CPET Reactivity: Mechanistic Crossover in H-Atom Abstraction by Co(III)-Oxo Complexes. J Am Chem Soc 2023; 145:5664-5673. [PMID: 36867838 PMCID: PMC10023487 DOI: 10.1021/jacs.2c10553] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Transition metal-oxo complexes are key intermediates in a variety of oxidative transformations, notably C-H bond activation. The relative rate of C-H bond activation mediated by transition metal-oxo complexes is typically predicated on substrate bond dissociation free energy in cases with a concerted proton-electron transfer (CPET). However, recent work has demonstrated that alternative stepwise thermodynamic contributions such as acidity/basicity or redox potentials of the substrate/metal-oxo may dominate in some cases. In this context, we have found basicity-governed concerted activation of C-H bonds with the terminal CoIII-oxo complex PhB(tBuIm)3CoIIIO. We have been interested in testing the limits of such basicity-dependent reactivity and have synthesized an analogous, more basic complex, PhB(AdIm)3CoIIIO, and studied its reactivity with H-atom donors. This complex displays a higher degree of imbalanced CPET reactivity than PhB(tBuIm)3CoIIIO with C-H substrates, and O-H activation of phenol substrates displays mechanistic crossover to stepwise proton transfer-electron transfer (PTET) reactivity. Analysis of the thermodynamics of proton transfer (PT) and electron transfer (ET) reveals a distinct thermodynamic crossing point between concerted and stepwise reactivity. Furthermore, the relative rates of stepwise and concerted reactivity suggest that maximally imbalanced systems provide the fastest CPET rates up to the point of mechanistic crossover, which results in slower product formation.
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Affiliation(s)
- Norman Zhao
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States
| | | | - Joseph E. Schneider
- Department of Chemistry, 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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4
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Insights into Molecular Structure of Pterins Suitable for Biomedical Applications. Int J Mol Sci 2022; 23:ijms232315222. [PMID: 36499560 PMCID: PMC9737128 DOI: 10.3390/ijms232315222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/22/2022] [Accepted: 11/30/2022] [Indexed: 12/07/2022] Open
Abstract
Pterins are an inseparable part of living organisms. Pterins participate in metabolic reactions mostly as tetrahydropterins. Dihydropterins are usually intermediates of these reactions, whereas oxidized pterins can be biomarkers of diseases. In this review, we analyze the available data on the quantum chemistry of unconjugated pterins as well as their photonics. This gives a comprehensive overview about the electronic structure of pterins and offers some benefits for biomedicine applications: (1) one can affect the enzymatic reactions of aromatic amino acid hydroxylases, NO synthases, and alkylglycerol monooxygenase through UV irradiation of H4pterins since UV provokes electron donor reactions of H4pterins; (2) the emission properties of H2pterins and oxidized pterins can be used in fluorescence diagnostics; (3) two-photon absorption (TPA) should be used in such pterin-related infrared therapy because single-photon absorption in the UV range is inefficient and scatters in vivo; (4) one can affect pathogen organisms through TPA excitation of H4pterin cofactors, such as the molybdenum cofactor, leading to its detachment from proteins and subsequent oxidation; (5) metal nanostructures can be used for the UV-vis, fluorescence, and Raman spectroscopy detection of pterin biomarkers. Therefore, we investigated both the biochemistry and physical chemistry of pterins and suggested some potential prospects for pterin-related biomedicine.
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Kim S, Choi J, Cho DW, Ahn M, Eom S, Kim J, Wee KR, Ihee H. Solvent-modulated proton-coupled electron transfer in an iridium complex with an ESIPT ligand. Chem Sci 2022; 13:3809-3818. [PMID: 35432886 PMCID: PMC8966730 DOI: 10.1039/d1sc07250a] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 03/03/2022] [Indexed: 11/21/2022] Open
Abstract
Proton-coupled electron transfer (PCET), an essential process in nature with a well-known example of photosynthesis, has recently been employed in metal complexes to improve the energy conversion efficiency; however, a profound understanding of the mechanism of PCET in metal complexes is still lacking. In this study, we synthesized cyclometalated Ir complexes strategically designed to exploit the excited-state intramolecular proton transfer (ESIPT) of the ancillary ligand and studied their photoinduced PCET in both aprotic and protic solvent environments using femtosecond transient absorption spectroscopy and density functional theory (DFT) and time-dependent DFT calculations. The data reveal solvent-modulated PCET, where charge transfer follows proton transfer in an aprotic solvent and the temporal order of charge transfer and proton transfer is reversed in a protic solvent. In the former case, ESIPT from the enol form to the keto form, which precedes the charge transfer from Ir to the ESIPT ligand, improves the efficiency of metal-to-ligand charge transfer. This finding demonstrates the potential to control the PCET reaction in the desired direction and the efficiency of charge transfer by simply perturbing the external hydrogen-bonding network with the solvent. The iridium complex with an ESIPT ligand shows solvent-modulated proton-coupled electron transfer, in which the temporal order of proton transfer and charge transfer is altered by the solvent environment.![]()
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Affiliation(s)
- Siin Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science Daejeon 34141 Republic of Korea
| | - Jungkweon Choi
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science Daejeon 34141 Republic of Korea
| | - Dae Won Cho
- Department of Advanced Materials Chemistry, Korea University, Sejong Campus Sejong 30019 Korea
| | - Mina Ahn
- Department of Chemistry and Institute of Natural Science, Daegu University Gyeongsan 38453 Republic of Korea
| | - Seunghwan Eom
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science Daejeon 34141 Republic of Korea
| | - Jungmin Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science Daejeon 34141 Republic of Korea
| | - Kyung-Ryang Wee
- Department of Chemistry and Institute of Natural Science, Daegu University Gyeongsan 38453 Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science Daejeon 34141 Republic of Korea
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Sharma N, Zou HB, Lee YM, Fukuzumi S, Nam W. A Mononuclear Non-Heme Manganese(III)-Aqua Complex in Oxygen Atom Transfer Reactions via Electron Transfer. J Am Chem Soc 2021; 143:1521-1528. [PMID: 33439643 DOI: 10.1021/jacs.0c11420] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Metal-oxygen complexes, such as metal-oxo [M(O2-)], -hydroxo [M(OH-)], -peroxo [M(O22-)], -hydroperoxo [M(OOH-)], and -superoxo [M(O2•-)] species, are capable of conducting oxygen atom transfer (OAT) reactions with organic substrates, such as thioanisole (PhSMe) and triphenylphosphine (Ph3P). However, OAT of metal-aqua complexes, [M(OH2)]n+, has yet to be reported. We report herein OAT of a mononuclear non-heme Mn(III)-aqua complex, [(dpaq)MnIII(OH2)]2+ (1, dpaq = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-yl-acetamidate), to PhSMe and Ph3P derivatives for the first time; it is noted that no OAT occurs from the corresponding Mn(III)-hydroxo complex, [(dpaq)MnIII(OH)]+ (2), to the substrates. Mechanistic studies reveal that OAT reaction of 1 occurs via electron transfer from 4-methoxythioanisole to 1 to produce the 4-methoxythioanisole radical cation and [(dpaq)MnII(OH2)]+, followed by nucleophilic attack of H2O in [(dpaq)MnII(OH2)]+ to the 4-methoxythioanisole radical cation to produce an OH adduct radical, 2,4-(MeO)2C6H3S•(OH)Me, which disproportionates or undergoes electron transfer to 1 to yield methyl 4-methoxyphenyl sulfoxide. Formation of the thioanisole radical cation derivatives is detected by the stopped-flow transient absorption measurements in OAT from 1 to 2,4-dimethoxythioanisole and 3,4-dimethoxythioanisole, being compared with that in the photoinduced electron transfer oxidation of PhSMe derivatives, which are detected by laser-induced transient absorption measurements. Similarly, OAT from 1 to Ph3P occurs via electron transfer from Ph3P to 1, and the proton effect on the reaction rate has been discussed. The rate constants of electron transfer from electron donors, including PhSMe and Ph3P derivatives, to 1 are fitted well by the electron transfer driving force dependence of the rate constants predicted by the Marcus theory of outer-sphere electron transfer.
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Affiliation(s)
- Namita Sharma
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Huai-Bo Zou
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,Department of Chemistry and Bioengineering, Key Laboratory of Jiangxi University for Applied Chemistry and Chemical Biology, Yichun University, Yichun 336000, China
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,Faculty of Science and Engineering, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
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Matias TA, Keppler AF, Bartoloni FH. In need of a second-hand? The second coordination sphere of ruthenium complexes enables water oxidation with improved catalytic activity. Dalton Trans 2020; 49:16034-16046. [DOI: 10.1039/d0dt02958k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A ligand dangling arm, acting as an intramolecular proton acceptor, drastically increasing the catalytic activity of Ru-complexes for water oxidation.
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Affiliation(s)
- Tiago A. Matias
- Center for Natural and Human Sciences (CCNH)
- Federal University of ABC (UFABC)
- Santo André
- Brazil
- Institute of Chemistry
| | - Artur F. Keppler
- Center for Natural and Human Sciences (CCNH)
- Federal University of ABC (UFABC)
- Santo André
- Brazil
| | - Fernando H. Bartoloni
- Center for Natural and Human Sciences (CCNH)
- Federal University of ABC (UFABC)
- Santo André
- Brazil
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8
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Fukuzumi S, Cho KB, Lee YM, Hong S, Nam W. Mechanistic dichotomies in redox reactions of mononuclear metal–oxygen intermediates. Chem Soc Rev 2020; 49:8988-9027. [DOI: 10.1039/d0cs01251c] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This review article focuses on various mechanistic dichotomies in redox reactions of metal–oxygen intermediates with the emphasis on understanding and controlling their redox reactivity from experimental and theoretical points of view.
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Affiliation(s)
- Shunichi Fukuzumi
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 03760
- Korea
- Graduate School of Science and Engineering
| | - Kyung-Bin Cho
- Department of Chemistry
- Jeonbuk National University
- Jeonju 54896
- Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 03760
- Korea
| | - Seungwoo Hong
- Department of Chemistry
- Sookmyung Women's University
- Seoul 04310
- Korea
| | - Wonwoo Nam
- Department of Chemistry and Nano Science
- Ewha Womans University
- Seoul 03760
- Korea
- School of Chemistry and Chemical Engineering
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