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Debnath S, Laxmi S, McCubbin Stepanic O, Quek SY, van Gastel M, DeBeer S, Krämer T, England J. A Four-Coordinate End-On Superoxocopper(II) Complex: Probing the Link between Coordination Number and Reactivity. J Am Chem Soc 2024; 146:23704-23716. [PMID: 39192778 PMCID: PMC11363018 DOI: 10.1021/jacs.3c12268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 07/12/2024] [Accepted: 07/19/2024] [Indexed: 08/29/2024]
Abstract
Although the reactivity of five-coordinate end-on superoxocopper(II) complexes, CuII(η1-O2•-), is dominated by hydrogen atom transfer, the majority of four-coordinate CuII(η1-O2•-) complexes published thus far display nucleophilic reactivity. To investigate the origin of this difference, we have developed a four-coordinate end-on superoxocopper(II) complex supported by a sterically encumbered bis(2-pyridylmethyl)amine ligand, dpb2-MeBPA (1), and compared its substrate reactivity with that of a five-coordinate end-on superoxocopper(II) complex ligated by a similarly substituted tris(2-pyridylmethyl)amine, dpb3-TMPA (2). Kinetic isotope effect (KIE) measurements and correlation of second-order rate constants (k2's) versus oxidation potentials (Eox) for a range of phenols indicates that the complex [CuII(η1-O2•-)(1)]+ reacts with phenols via a similar hydrogen atom transfer (HAT) mechanism to [CuII(η1-O2•-)(2)]+. However, [CuII(η1-O2•-)(1)]+ performs HAT much more quickly, with its k2 for reaction with 2,6-di-tert-butyl-4-methoxyphenol (MeO-ArOH) being >100 times greater. Furthermore, [CuII(η1-O2•-)(1)]+ can oxidize C-H bond substrates possessing stronger bonds than [CuII(η1-O2•-)(2)]+ is able to, and it reacts with N-methyl-9,10-dihydroacridine (MeAcrH2) approximately 200 times faster. The much greater facility for substrate oxidation displayed by [CuII(η1-O2•-)(1)]+ is attributed to it possessing higher inherent electrophilicity than [CuII(η1-O2•-)(2)]+, which is a direct consequence of its lower coordination number. These observations are of relevance to enzymes in which four-coordinate end-on superoxocopper(II) intermediates, rather than their five-coordinate congeners, are routinely invoked as the active oxidants responsible for substrate oxidation.
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Affiliation(s)
- Suman Debnath
- Division
of Chemistry and Biological Chemistry, School of Chemistry, Chemical
Engineering and Biotechnology, Nanyang Technological
University, 21 Nanyang Link, 637371 Singapore
| | - Shoba Laxmi
- Division
of Chemistry and Biological Chemistry, School of Chemistry, Chemical
Engineering and Biotechnology, Nanyang Technological
University, 21 Nanyang Link, 637371 Singapore
| | - Olivia McCubbin Stepanic
- Max
Planck Institute for Chemical Energy Conversion, Stiftstr. 34–36, Mülheim an der Ruhr D-45470, Germany
| | - Sebastian Y. Quek
- Division
of Chemistry and Biological Chemistry, School of Chemistry, Chemical
Engineering and Biotechnology, Nanyang Technological
University, 21 Nanyang Link, 637371 Singapore
| | - Maurice van Gastel
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz, Mülheim
an der Ruhr D-45470, Germany
| | - Serena DeBeer
- Max
Planck Institute for Chemical Energy Conversion, Stiftstr. 34–36, Mülheim an der Ruhr D-45470, Germany
| | - Tobias Krämer
- Department
of Chemistry, Maynooth University, Maynooth W23 F2H6, Co. Kildare, Ireland
- Hamilton
Institute, Maynooth University, Maynooth W23 F2H6, Co. Kildare, Ireland
| | - Jason England
- Division
of Chemistry and Biological Chemistry, School of Chemistry, Chemical
Engineering and Biotechnology, Nanyang Technological
University, 21 Nanyang Link, 637371 Singapore
- School
of
Chemistry, University of Lincoln, Lincoln LN6 7TW, U.K.
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2
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Mu YL, He Q, Li CY, Sheng D, Wu SH, Liu Y, Ren HT, Han X. Contributions of Surface Oxidizing Species and Cu + to the Antibacterial Activities of Cu 2O with Different Crystalline Structures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 39137090 DOI: 10.1021/acs.langmuir.4c00984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
Although precise regulation of the crystalline structures of metal oxides is an effective method to improve their antibacterial activities, the corresponding mechanisms involved in this process are still unclear. In this study, three kinds of cuprous oxide (Cu2O) samples with different structures of cubes, octahedra, and rhombic dodecahedra (c-Cu2O, o-Cu2O, and r-Cu2O) have been successfully synthesized and their antibacterial activities are compared. The antibacterial activities follow the order of r-Cu2O > o-Cu2O > c-Cu2O, revealing the significant dependence of the antibacterial activities on the crystalline structures of Cu2O. Quenching experiments, as well as the NBT and DPD experiments indicate that ≡CuII─OO• superoxo and ≡CuII─OOH peroxo, instead of •OH, O2•-, and H2O2, are the primary oxidizing species in the oxidative damage to E. coli. Raman analysis further confirms the presence of both ≡CuII─OO• superoxo and ≡CuII─OOH peroxo on the surface of r-Cu2O. On the other hand, the NCP experiment reveals that Cu+, instead of Cu2+, also contributes to the antibacterial process. This study provides new insight into the antibacterial mechanisms of Cu2O.
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Affiliation(s)
- Yun-Long Mu
- Tianjin Key Laboratory of Chemical Process Safety and Equipment Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, PR China
| | - Qing He
- Instrument analysis and testing center, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, PR China
| | - Chun-Yan Li
- Tianjin Key Laboratory of Chemical Process Safety and Equipment Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, PR China
| | - Da Sheng
- Tianjin Key Laboratory of Chemical Process Safety and Equipment Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, PR China
| | - Song-Hai Wu
- Tianjin Key Laboratory of Chemical Process Safety and Equipment Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, PR China
| | - Yong Liu
- School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, PR China
| | - Hai-Tao Ren
- School of Textile Science and Engineering, Tiangong University, Tianjin 300387, PR China
| | - Xu Han
- Tianjin Key Laboratory of Chemical Process Safety and Equipment Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, PR China
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3
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Zhou X, Qian F, Zhou W, Wang A, Hou T, Tian X, Ji S, He M, Qian J. Cooperation between the Cu + and Cu 2+ species in CuCoAl layered double hydroxide and the substrate promoting effect afford a really simple protocol for the efficient synthesis of quinazolines. Org Biomol Chem 2024; 22:4494-4501. [PMID: 38742377 DOI: 10.1039/d4ob00481g] [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
In this study, a really simple and efficient catalytic protocol for the construction of quinazolines from alcohol and diamine has been developed based on CuCoAl layered double hydroxide (CuCoAl-LDH). The developed CuCoAl-LDH catalyst could accelerate the cascade reactions without any additives and tolerate various alcohols with satisfactory yields. Cooperation between the Cu+ and Cu2+ species in CuCoAl-LDH was observed in the cascade reaction, and they are believed to be responsible for the oxidation of alcohol and dehydrogenation of the intermediate, respectively. The promoting effect of the substrate diamine was observed in the oxidation of alcohol, which simplifies the reaction system by eliminating the requirement for a base additive. The catalytic system exhibited highly practical potential for the synthesis of quinazolines, as demonstrated through recyclability investigations and scale-up experiments. A possible catalytic mechanism has been proposed based on a series of control experiments and EPR analysis.
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Affiliation(s)
- Xue Zhou
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, 213164 Changzhou, China
| | - Fei Qian
- Jiangsu Lingfei Chemical Co., LTD, Wuxi 214264, China
| | - Weiyou Zhou
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, 213164 Changzhou, China
| | - Anwei Wang
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, 213164 Changzhou, China
| | - Tao Hou
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, 213164 Changzhou, China
| | - Xiaoting Tian
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, 213164 Changzhou, China
| | - Shuliang Ji
- Jiangsu Yabang Dyestuff Co., LTD, 213163 Changzhou, China
| | - Mingyang He
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, 213164 Changzhou, China
| | - Junfeng Qian
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, 213164 Changzhou, China
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4
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Rush KW, Eastman KAS, Welch EF, Bandarian V, Blackburn NJ. Capturing the Binuclear Copper State of Peptidylglycine Monooxygenase Using a Peptidyl-Homocysteine Lure. J Am Chem Soc 2024; 146:5074-5080. [PMID: 38363651 PMCID: PMC11096088 DOI: 10.1021/jacs.3c14705] [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] [Indexed: 02/18/2024]
Abstract
Peptidylglycine monooxygenase is a copper-dependent enzyme that catalyzes C-alpha hydroxylation of glycine extended pro-peptides, a critical post-translational step in peptide hormone processing. The canonical mechanism posits that dioxygen binds at the mononuclear M-center to generate a Cu(II)-superoxo species capable of H atom abstraction from the peptidyl substrate, followed by long-range electron tunneling from the CuH center. Recent crystallographic and biochemical data have challenged this mechanism, suggesting instead that an "open-to-closed" transition brings the copper centers closer, allowing reactivity within a binuclear intermediate. Here we present the first direct observation of an enzyme-bound binuclear copper species, captured by the use of an Ala-Ala-Phe-hCys inhibitor complex. This molecule reacts with the fully reduced enzyme to form a thiolate-bridged binuclear species characterized by EXAFS of the WT and its M314H variant and with the oxidized enzyme to form a novel mixed valence entity characterized by UV/vis and EPR. Mechanistic implications are discussed.
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Affiliation(s)
- Katherine W. Rush
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA
| | | | - Evan F. Welch
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA
| | - Vahe Bandarian
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Ninian J. Blackburn
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA
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5
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Mohammed TP, George A, Sivaramakrishnan MP, Vadivelu P, Balasubramanian S, Sankaralingam M. Deciphering the effect of amine versus imine ligands of copper(II) complexes in 2-aminophenol oxidation. J Inorg Biochem 2023; 247:112309. [PMID: 37451084 DOI: 10.1016/j.jinorgbio.2023.112309] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/19/2023] [Accepted: 06/27/2023] [Indexed: 07/18/2023]
Abstract
A series of amine (1-6) and imine (5',6') based copper(II) complexes with tridentate (NNO) ligand donors were synthesized and characterized using modern analytical techniques. All the complexes were subjected to 2-aminophenol (OAP) oxidation to form 2-aminophenoxazin-3-one, as a functional analogue of an enzyme, phenoxazinone synthase. In addition, a critical comparison of the reactivity using the amine-based complexes with their respective imine counterparts was achieved in both experimental as well as theoretical studies. For instance, the kinetic measurement revealed that the imine-based copper(II) complexes (kcat, 2.4 × 105-6.2 × 106 h-1) are better than amine-based (kcat, 6.3 × 104-3.9 × 105 h-1) complexes. The complex-substrate adducts [Cu(L3)(OAP)] (7) and [Cu(L3')(OAP)] (7') were characterized for both systems by mass spectrometry. Further, the DFT study was performed with amine- (3) and imine- (3') based copper(II) complexes, to compare their efficacy in the oxidation of OAP. The mechanistic investigations reveal that the key elementary step to determine the reactivity of 3 and 3' is the proton-coupled electron transfer (PCET) step occurring from the intermediates 7/7'. Further, the computed HOMO-LUMO energy gap of 7' was smaller than 7 by 0.8 eV, which indicates the facile PCET compared to that of 7. Moreover, the coupling of the OAP moiety using imine-complexes (ΔGR.E = -5.8 kcal/mol) was found to be thermodynamically more favorable than amine complexes (ΔGR.E = +3.3 kcal/mol). Overall, the theoretical findings are in good agreement with the experimental results.
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Affiliation(s)
- Thasnim P Mohammed
- Bioinspired & Biomimetic Inorganic Chemistry Lab, Department of Chemistry, National Institute of Technology Calicut, Kozhikode, Kerala 673601, India
| | - Akhila George
- Bioinspired & Biomimetic Inorganic Chemistry Lab, Department of Chemistry, National Institute of Technology Calicut, Kozhikode, Kerala 673601, India
| | | | - Prabha Vadivelu
- Department of Chemistry, Central University of Tamil Nadu, Thiruvarur 610 005, India
| | - Sridhar Balasubramanian
- Centre for X-ray Crystallography, CSIR-Indian Institute of Chemical Technology, Hyderabad, Telangana 500007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Muniyandi Sankaralingam
- Bioinspired & Biomimetic Inorganic Chemistry Lab, Department of Chemistry, National Institute of Technology Calicut, Kozhikode, Kerala 673601, India.
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6
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Kim B, Karlin KD. Ligand-Copper(I) Primary O 2-Adducts: Design, Characterization, and Biological Significance of Cupric-Superoxides. Acc Chem Res 2023; 56:2197-2212. [PMID: 37527056 PMCID: PMC11152209 DOI: 10.1021/acs.accounts.3c00297] [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] [Indexed: 08/03/2023]
Abstract
In this Account, we overview and highlight synthetic bioinorganic chemistry focused on initial adducts formed from the reaction of reduced ligand-copper(I) coordination complexes with molecular oxygen, reactions that produce ligand-CuII(O2•-) complexes (O2•- ≡ superoxide anion). We provide mostly a historical perspective, starting in the Karlin research group in the 1980s, emphasizing the ligand design and ligand effects, structure, and spectroscopy of these O2 adducts and subsequent further reactivity with substrates, including the interaction with a second ligand-CuI complex to form binuclear species. The Account emphasizes the approach, evolution, and results obtained in the Karlin group, a synthetic bioinorganic research program inspired by the state of knowledge and insights obtained on enzymes possessing copper ion active sites which process molecular oxygen. These constitute an important biochemistry for all levels/types of organisms, bacteria, fungi, insects, and mammals, including humans.Copper is earth abundant, and its redox properties in complexes allow for facile CuII/CuI interconversions. Simple salts or coordination complexes have been well known to serve as oxidants for the stoichiometric or catalytic oxidation or oxygenation (i.e., O-atom insertion) of organic substrates. Thus, copper dioxygen- or peroxide-centered synthetic bioinorganic studies provide strong relevance and potential application to synthesis or even the development of cathodic catalysts for dioxygen reduction to hydrogen peroxide or water, as in fuel cells. The Karlin group's focus however was primarily oriented toward bioinorganic chemistry with the goal to provide fundamental insights into the nature of copper-dioxygen adducts and further reduced and/or protonated derivatives, species likely occurring in enzyme turnover or related in one or more aspects of formation, structure, spectroscopic properties, and scope of reactivity toward organic/biochemical substrates.Prior to this time, the 1980s, O2 adducts of redox-active first-row transition-metal ions focused on iron, such as the porphyrinate-Fe centers occurring in the oxygen carrier proteins myoglobin and hemoglobin and that determined to occur in cytochrome P-450 monooxygenase turnover. Deoxy (i.e., reduced Fe(II)) heme proteins react with O2, giving FeIII-superoxo complexes (preferably referred to by traditional biochemists as ferrous-oxy species). And, it was in the 1970s that great strides were made by synthetic chemists in generating hemes capable of forming O2 adducts, their physiochemical characterization providing critical insights to enzyme (bio)chemistry and providing ideas and important goals leading to countless person years of future research.
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Affiliation(s)
- Bohee Kim
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D Karlin
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
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7
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Alkane hydroxylation by m-chloroperbenzoic acid catalyzed by nickel(II) complexes of linear N4-tetradentate ligands. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.116150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Novel Copper Complexes as Visible Light Photoinitiators for the Synthesis of Interpenetrating Polymer Networks (IPNs). Polymers (Basel) 2022; 14:polym14101998. [PMID: 35631880 PMCID: PMC9145974 DOI: 10.3390/polym14101998] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/07/2022] [Accepted: 05/09/2022] [Indexed: 12/16/2022] Open
Abstract
This work is devoted to the study of two copper complexes (Cu) bearing pyridine ligands, which were synthesized, evaluated and tested as new visible light photoinitiators for the free radical photopolymerization (FRP) of acrylates functional groups in thick and thin samples upon light-emitting diodes (LED) at 405 and 455 nm irradiation. These latter wavelengths are considered to be safe to produce polymer materials. The photoinitiation abilities of these organometallic compounds were evaluated in combination with an iodonium (Iod) salt and/or amine (e.g., N-phenylglycine—NPG). Interestingly, high final conversions and high polymerization rates were obtained for both compounds using two and three-component photoinitiating systems (Cu1 (or Cu2)/Iodonium salt (Iod) (0.1%/1% w/w) and Cu1 (or Cu2)/Iod/amine (0.1%/1%/1% w/w/w)). The new proposed copper complexes were also used for direct laser write experiments involving a laser diode at 405 nm, and for the photocomposite synthesis with glass fibers using a UV-conveyor at 395 nm. To explain the obtained polymerization results, different methods and characterization techniques were used: steady-state photolysis, real-time Fourier transform infrared spectroscopy (RT-FTIR), emission spectroscopy and cyclic voltammetry.
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9
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Thennarasu AS, Mohammed TP, Sankaralingam M. Mononuclear copper( ii) Schiff base complexes as effective models for phenoxazinone synthase. NEW J CHEM 2022. [DOI: 10.1039/d2nj03934f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Copper(ii) complexes of tridentate (N2O) Schiff base ligands as efficient catalysts for 2-aminophenol oxidation to 2-aminophenoxazin-3-one with excellent reaction rates.
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Affiliation(s)
- Abinaya Sushana Thennarasu
- Bioinspired & Biomimetic Inorganic Chemistry Lab, Department of Chemistry, National Institute of Technology Calicut, Kozhikode, Kerala 673601, India
| | - Thasnim P Mohammed
- Bioinspired & Biomimetic Inorganic Chemistry Lab, Department of Chemistry, National Institute of Technology Calicut, Kozhikode, Kerala 673601, India
| | - Muniyandi Sankaralingam
- Bioinspired & Biomimetic Inorganic Chemistry Lab, Department of Chemistry, National Institute of Technology Calicut, Kozhikode, Kerala 673601, India
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10
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Quek SY, Debnath S, Laxmi S, van Gastel M, Krämer T, England J. Sterically Stabilized End-On Superoxocopper(II) Complexes and Mechanistic Insights into Their Reactivity with O-H, N-H, and C-H Substrates. J Am Chem Soc 2021; 143:19731-19747. [PMID: 34783549 DOI: 10.1021/jacs.1c07837] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Instability of end-on superoxocopper(II) complexes, with respect to conversion to peroxo-bridged dicopper(II) complexes, has largely constrained their study to very low temperatures. This limits their kinetic capacity to oxidize substrates. In response, we have developed a series of bulky ligands, Ar3-TMPA (Ar = tpb, dpb, dtbpb), and used them to support copper(I) complexes that react with O2 to yield [CuII(η1-O2•-)(Ar3-TMPA)]+ species, which are stable against dimerization at all temperatures. Binding of O2 saturates at subambient temperatures and can be reversed by warming. The onset of oxygenation for the Ar = tpb and dpb systems is observed at 25 °C, and all three [CuII(η1-O2•-)(Ar3-TMPA)]+ complexes are stable against self-decay at temperatures of ≤-20 °C. This provides a wide temperature window for study of these complexes, which was exploited by performing extensive reaction kinetics measurements for [CuII(η1-O2•-)(tpb3-TMPA)]+ using a broad range of O-H, N-H, and C-H bond substrates. This includes correlation of second order rate constants (k2) versus oxidation potentials (Eox) for a range of phenols, construction of Eyring plots, and temperature-dependent kinetic isotope effect (KIE) measurements. The data obtained indicate that reaction with all substrates proceeds via H atom transfer (HAT), reaction with the phenols proceeds with significant charge transfer, and full tunneling of both H and D atoms occurs in the case of 1,2-diphenylhydrazine and 4-methoxy-2,6-di-tert-butylphenol. Oxidation of C-H bonds proved to be kinetically challenging, and whereas [CuII(η1-O2•-)(tpb3-TMPA)]+ can oxidize moderately strong O-H and N-H bonds, it is only able to oxidize very weak C-H bonds.
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Affiliation(s)
- Sebastian Y Quek
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Suman Debnath
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Shoba Laxmi
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr D-45470, Germany
| | - Tobias Krämer
- Department of Chemistry, Maynooth University, Maynooth, Co. Kildare W23 F2H6, Ireland.,Hamilton Institute, Maynooth University, Maynooth, Co. Kildare W23 F2H6, Ireland
| | - Jason England
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.,Department of Chemistry, University of Lincoln, Lincoln LN6 7TW, U.K
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11
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Morimoto Y, Kawai M, Nakanishi A, Sugimoto H, Itoh S. Controlling the Reactivity of Copper(II) Acylperoxide Complexes. Inorg Chem 2021; 60:8554-8565. [PMID: 33848148 DOI: 10.1021/acs.inorgchem.1c00475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The redox state of the metallomonooxygenases is finely tuned by imposing specific coordination environments on the metal center to reduce the activation energy for the generation of active-oxygen species and subsequent substrate oxygenation reactions. In this study, copper(II) complexes supported by a series of linear tetradentate ligands consisting of a rigid 6-, 7-, or 8-membered cyclic diamine with two pyridylmethyl (-CH2Py) side arms (L6Pym2, L7Pym2, and L8Pym2) are employed to examine the effects of the coordination environment on the reactivity of their acylperoxide adduct complexes. The UV-vis and electron paramagnetic resonance spectroscopic data indicate that the ligand-field splitting between the dx2-y2 and dz2 orbitals of the starting copper(II) complexes increase with an increase of the ring size of the diamine moiety (L6Pym2 → L7Pym2 → L8Pym2). In the reaction of these copper(II) complexes with m-chloroperbenzoic acid (m-CPBA), the L6Pym2 complex gives a stable m-CPBA adduct complex, whereas the L7Pym2 and L8Pym2 complexes are immediately converted to the corresponding m-chlorobenzoic acid (m-CBA) adducts, indicating that the reactivity of the copper(II) acylperoxide complexes largely depends on the coordination environment induced by the supporting ligands. Density functional theory (DFT) calculations on the m-CPBA adduct complexes show that the ligand-field-splitting energy increases with an increase of the ring size of the diamine moiety, as in the case of the starting copper(II) complexes, which enhances the reactivity of the m-CPBA adduct complexes. The reasons for such different reactivities of the m-CPBA adduct complexes are evaluated by using DFT calculations.
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Affiliation(s)
- Yuma Morimoto
- Department of Molecular Chemistry, Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Makito Kawai
- Department of Molecular Chemistry, Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Aya Nakanishi
- Department of Molecular Chemistry, Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hideki Sugimoto
- Department of Molecular Chemistry, Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shinobu Itoh
- Department of Molecular Chemistry, Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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12
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Sawaki T, Ishizuka T, Namura N, Hong D, Miyanishi M, Shiota Y, Kotani H, Yoshizawa K, Jung J, Fukuzumi S, Kojima T. Photocatalytic hydrogen evolution using a Ru(ii)-bound heteroaromatic ligand as a reactive site. Dalton Trans 2020; 49:17230-17242. [PMID: 33210674 DOI: 10.1039/d0dt03546g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A RuII complex, [RuII(tpphz)(bpy)2]2+ (1) (tpphz = tetrapyridophenazine, bpy = 2,2'-bipyridine), whose tpphz ligand has a pyrazine moiety, is converted efficiently to [RuII(tpphz-HH)(bpy)2]2+ (2) having a dihydropyrazine moiety upon photoirradiation of a water-methanol mixed solvent solution of 1 in the presence of an electron donor. In this reaction, the triplet metal-to-ligand charge-transfer excited state (3MLCT*) of 1 is firstly formed upon photoirradiation and the 3MLCT* state is reductively quenched with an electron donor to afford [RuII(tpphz˙-)(bpy)2]+, which is converted to 2 without the observation of detectable reduced intermediates by nano-second laser flash photolysis. The inverse kinetic isotope effect (KIE) was observed to be 0.63 in the N-H bond formation of 2 at the dihydropyrazine moiety. White-light (380-670 nm) irradiation of a solution of 1 in a protic solvent, in the presence of an electron donor under an inert atmosphere, led to photocatalytic H2 evolution and the hydrogenation of organic substrates. In the reactions, complex 2 is required to be excited to form its 3MLCT* state to react with a proton and aldehydes. In photocatalytic H2 evolution, the H-H bond formation between photoexcited 2 and a proton is involved in the rate-determining step with normal KIE being 5.2 on H2 evolving rates. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations on the reaction mechanism of H2 evolution from the ground and photo-excited states of 2 were performed to have a better understanding of the photocatalytic processes.
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Affiliation(s)
- Takuya Sawaki
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba and CREST (JST), 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan.
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13
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Chen TY, Ho PH, Spyra CJ, Meyer F, Bill E, Ye S, Lee WZ. Ambiphilicity of a mononuclear cobalt(III) superoxo complex. Chem Commun (Camb) 2020; 56:14821-14824. [PMID: 33151205 DOI: 10.1039/d0cc05337f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Addition of HOTf to a mixture of CoIII(BDPP)(O2˙) (1, H2BDPP = 2,6-bis((2-(S)-diphenylhydroxylmethyl-1-pyrrolidinyl)methyl)pyridine) and Cp*2Fe produced H2O2 in high yield implying formation of CoIII(BDPP)(OOH) (3), and reaction of Sc(OTf)3 with the same mixture gave a peroxo-bridged CoIII/ScIII5. These findings demonstrate the ambiphilic property of CoIII-superoxo 1.
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Affiliation(s)
- Ting-Yi Chen
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan. and Universität Göttingen, Institut für Anorganische Chemie, D-37077 Göttingen, Germany.
| | - Po-Hsun Ho
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan.
| | - Can-Jerome Spyra
- Universität Göttingen, Institut für Anorganische Chemie, D-37077 Göttingen, Germany.
| | - Franc Meyer
- Universität Göttingen, Institut für Anorganische Chemie, D-37077 Göttingen, Germany.
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr D-45470, Germany.
| | - Shengfa Ye
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China. and Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, D-45470, Germany.
| | - Way-Zen Lee
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan. and Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan
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14
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Bhargava Reddy M, Prasanth K, Anandhan R. Visible-light induced copper(i)-catalyzed oxidative cyclization of o-aminobenzamides with methanol and ethanol via HAT. Org Biomol Chem 2020; 18:9601-9605. [PMID: 33226372 DOI: 10.1039/d0ob02234a] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The use of the in situ generated ligand-copper superoxo complex absorbing light energy to activate the alpha C(sp3)-H of MeOH and EtOH via the hydrogen atom transfer (HAT) process for the synthesis of quinazolinones by oxidative cyclization of alcohols with o-aminobenzamide has been investigated. The synthetic utility of this protocol offers an efficient synthesis of a quinazolinone intermediate for erlotinb (anti-cancer agent) and 30 examples were reported.
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15
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Mandal A, Sarkar A, Adhikary A, Samanta D, Das D. Structure and synthesis of copper-based Schiff base and reduced Schiff base complexes: a combined experimental and theoretical investigation of biomimetic catalytic activity. Dalton Trans 2020; 49:15461-15472. [PMID: 33141130 DOI: 10.1039/d0dt02784g] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three copper(ii) complexes, [Cu(L1)(NCS)]n (1), [Cu(L1)(N3)]n (2) and [Cu(L2)(N3)] (3) were synthesized from one Schiff base ligand and one reduced Schiff base ligand, (E)-4-chloro-2-[(2-propylaminoethylimino)methyl]phenol (HL1) and 4-chloro-2-[(2-(propylaminoethylamino) methyl]phenol (HL2), respectively. All complexes were characterized by various physicochemical studies, such as FT-IR, UV-Vis, ESI-MS, EPR and single crystal X-ray diffraction. Complexes 1 and 2 have 1D polymeric chain-like structures bridging through thiocyanate and azide anions, whereas complex 3 has a mononuclear structure in the solid state. All the complexes are active towards mimicking two well-known proteins, phosphatase and phenoxazinone synthase, using the disodium salt of 4-nitrophenylphosphate (4-NPP) and 2-aminophenol (OAP) as the substrate in DMF medium. Complexes 2 and 3 show the highest activity towards phosphatase and phenoxazinone synthase activity with kcat values of 22.6 s-1 and 134.4 h-1, respectively. EPR studies confirmed that for complex 1, the OAP oxidation goes through the generation of an organic radical at g = 1.99, which is due to an imine radical formation, whereas the metal center redox pathway is followed for complex 3. Extensive DFT calculations have been performed for both catalytic studies to put forward the most probable mechanistic pathways.
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Affiliation(s)
- Arnab Mandal
- Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata 700009, India.
| | - Abani Sarkar
- Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata 700009, India.
| | - Amit Adhikary
- Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata 700009, India.
| | - Debabrata Samanta
- Department of Chemistry, Dukhulal Nibaran Chandra (DNC) College, Aurangabad, West Bengal 742201, India
| | - Debasis Das
- Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata 700009, India.
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16
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Álvarez M, Molina F, Fructos MR, Urbano J, Álvarez E, Sodupe M, Lledós A, Pérez PJ. Aerobic intramolecular carbon-hydrogen bond oxidation promoted by Cu(I) complexes. Dalton Trans 2020; 49:14647-14655. [PMID: 33057511 DOI: 10.1039/d0dt03198d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The oxidation of C-H bonds by copper centres in enzymes with molecular oxygen takes place in nature under ambient conditions. Herein we report a similar transformation in which under ambient pressure and temperature (1 atm, 25 °C) the complex TpMsCu(THF) (TpMs = hydrotris(3-mesityl-pyrazol-1-yl)borate) undergoes the intramolecular oxidation of an alkylic C-H bond with O2, leading to the formation of a trinuclear compound where alkoxy and hydroxyl ligands are bonded to the copper centres, as inferred from X-ray studies. The presence of adventitious Cu(0) derived from the partial decomposition of initial TpMsCu(THF) facilitates the formation of such a trinuclear compound. DFT studies support the reaction taking place through a Cu(iii) alkoxy-hydroxyl copper intermediate.
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Affiliation(s)
- María Álvarez
- Laboratorio de Catálisis Homogénea, Unidad Asociada al CSIC CIQSO-Centro de Investigación en Química Sostenible and Departamento de Química, Universidad de Huelva, 21007-Huelva, Spain
| | - Francisco Molina
- Laboratorio de Catálisis Homogénea, Unidad Asociada al CSIC CIQSO-Centro de Investigación en Química Sostenible and Departamento de Química, Universidad de Huelva, 21007-Huelva, Spain
| | - Manuel R Fructos
- Laboratorio de Catálisis Homogénea, Unidad Asociada al CSIC CIQSO-Centro de Investigación en Química Sostenible and Departamento de Química, Universidad de Huelva, 21007-Huelva, Spain
| | - Juan Urbano
- Departamento de Química, Universidad de Huelva, 21007-Huelva, Spain
| | - Eleuterio Álvarez
- Instituto de Investigaciones Químicas, Centro de Investigaciones Isla de la Cartuja, Avda Américo Vespucio 49, 41092 Sevilla, Spain
| | - Mariona Sodupe
- Departament de Química, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain.
| | - Agustí Lledós
- Departament de Química, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain.
| | - Pedro J Pérez
- Laboratorio de Catálisis Homogénea, Unidad Asociada al CSIC CIQSO-Centro de Investigación en Química Sostenible and Departamento de Química, Universidad de Huelva, 21007-Huelva, Spain
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17
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Kripli B, Szávuly M, Csendes FV, Kaizer J. Functional models of nonheme diiron enzymes: reactivity of the μ-oxo-μ-1,2-peroxo-diiron(iii) intermediate in electrophilic and nucleophilic reactions. Dalton Trans 2020; 49:1742-1746. [PMID: 31967142 DOI: 10.1039/c9dt04551a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The reactivity of the previously reported peroxo-adduct [FeIII2(μ-O)(μ-1,2-O2)(IndH)2(solv)2]2+ (1) (IndH = 1,3-bis(2-pyridyl-imino)isoindoline) has been investigated in nucleophilic (e.g., deformylation of alkyl and aryl alkyl aldehydes) and electrophilic (e.g. oxidation of phenols) stoichiometric reactions as biomimics of ribonucleotide reductase (RNR-R2) and aldehyde deformylating oxygenase (ADO) enzymes. Based on detailed kinetic and mechanistic studies, we have found further evidence for the ambiphilic behaviour of the peroxo intermediates proposed for diferric oxidoreductase enzymes.
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Affiliation(s)
- Balázs Kripli
- Department of Chemistry, University of Pannonia, H-8201 Veszprém, Hungary.
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18
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Mondal P, McDonald AR. Phenol Oxidation by a Nickel(III)-Fluoride Complex: Exploring the Influence of the Proton Accepting Ligand in PCET Oxidation. Chemistry 2020; 26:10083-10089. [PMID: 32567726 DOI: 10.1002/chem.202002135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/15/2020] [Indexed: 11/05/2022]
Abstract
In order to gain insight into the influence of the H+ -accepting terminal ligand in high-valent oxidant mediated proton coupled electron transfer (PCET) reactions, the reactivity of a high valent nickel-fluoride complex [NiIII (F)(L)] (2, L=N,N'-(2,6-dimethylphenyl)-2,6-pyridinecarboxamidate) with substituted phenols was explored. Analysis of kinetic data from these reactions (Evans-Polanyi, Hammett, and Marcus plots, and KIE measurements) and the formed products show that 2 reacted with electron rich phenols through a hydrogen atom transfer (HAT, or concerted PCET) mechanism and with electron poor phenols through a stepwise proton transfer/electron transfer (PT/ET) reaction mechanism. The analogous complexes [NiIII (Z)(L)] (Z=Cl, OCO2 H, O2 CCH3 , ONO2 ) reacted with all phenols through a HAT mechanism. We explore the reason for a change in mechanism with the highly basic fluoride ligand in 2. Complex 2 was also found to react one to two orders of magnitude faster than the corresponding analogous [NiIII (Z)(L)] complexes. This was ascribed to a high bond dissociation free energy value associated with H-F (135 kcal mol-1 ), which is postulated to be the product formed from PCET oxidation by 2 and is believed to be the driving force for the reaction. Our findings show that high-valent metal-fluoride complexes represent a class of highly reactive PCET oxidants.
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Affiliation(s)
- Prasenjit Mondal
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland
| | - Aidan R McDonald
- School of Chemistry, Trinity College Dublin, The University of Dublin, College Green, Dublin, 2, Ireland
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19
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Lin YH, Kutin Y, van Gastel M, Bill E, Schnegg A, Ye S, Lee WZ. A Manganese(IV)-Hydroperoxo Intermediate Generated by Protonation of the Corresponding Manganese(III)-Superoxo Complex. J Am Chem Soc 2020; 142:10255-10260. [PMID: 32412757 DOI: 10.1021/jacs.0c02756] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Earlier work revealed that metal-superoxo species primarily function as radicals and/or electrophiles. Herein, we present ambiphilicity of a MnIII-superoxo complex revealed by its proton- and metal-coupled electron-transfer processes. Specifically, a MnIV-hydroperoxo intermediate, [Mn(BDPBrP)(OOH)]+ (1, H2BDPBrP = 2,6-bis((2-(S)-di(4-bromo)phenylhydroxylmethyl-1-pyrrolidinyl)methyl)pyridine) was generated by treatment of a MnIII-superoxo complex, Mn(BDPBrP)(O2•) (2) with trifluoroacetic acid at -120 °C. Detailed insights into the electronic structure of 1 are obtained using resonance Raman and multi-frequency electron paramagnetic resonance spectroscopies coupled with density functional theory calculations. Similarly, the reaction of 2 with scandium(III) triflate was shown to give a Mn(IV)/Sc(III) bridging peroxo species, [Mn(BDPBrP)(OO)Sc(OTf)n](3-n)+ (4). Furthermore, it is found that deprotonation of 1 quantitatively regenerates 2, and that one-electron oxidation of the corresponding MnIII-hydroperoxo species, Mn(BDPBrP)(OOH) (3), also yields 1.
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Affiliation(s)
- Yen-Hao Lin
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Yury Kutin
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr D-45470, Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr D-45470, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr D-45470, Germany
| | - Alexander Schnegg
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr D-45470, Germany
| | - Shengfa Ye
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr D-45470, Germany.,State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Way-Zen Lee
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan.,Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan
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20
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Kim H, Rogler PJ, Sharma SK, Schaefer AW, Solomon EI, Karlin KD. Heme-Fe III Superoxide, Peroxide and Hydroperoxide Thermodynamic Relationships: Fe III-O 2•- Complex H-Atom Abstraction Reactivity. J Am Chem Soc 2020; 142:3104-3116. [PMID: 31913628 PMCID: PMC7034651 DOI: 10.1021/jacs.9b12571] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Establishing redox and thermodynamic relationships between metal-ion-bound O2 and its reduced (and protonated) derivatives is critically important for a full understanding of (bio)chemical processes involving dioxygen processing. Here, a ferric heme peroxide complex, [(F8)FeIII-(O22-)]- (P) (F8 = tetrakis(2,6-difluorophenyl)porphyrinate), and a superoxide complex, [(F8)FeIII-(O2•-)] (S), are shown to be redox interconvertible. Using Cr(η-C6H6)2, an equilibrium state where S and P are present is established in tetrahydrofuran (THF) at -80 °C, allowing determination of the reduction potential of S as -1.17 V vs Fc+/0. P could be protonated with 2,6-lutidinium triflate, yielding the low-spin ferric hydroperoxide species, [(F8)FeIII-(OOH)] (HP). Partial conversion of HP back to P using a derivatized phosphazene base gave a P/HP equilibrium mixture, leading to the determination of pKa = 28.8 for HP (THF, -80 °C). With the measured reduction potential and pKa, the O-H bond dissociation free energy (BDFE) of hydroperoxide species HP was calculated to be 73.5 kcal/mol, employing the thermodynamic square scheme and Bordwell relationship. This calculated O-H BDFE of HP, in fact, lines up with an experimental demonstration of the oxidizing ability of S via hydrogen atom transfer (HAT) from TEMPO-H (2,2,6,6-tetramethylpiperdine-N-hydroxide, BDFE = 66.5 kcal/mol in THF), forming the hydroperoxide species HP and TEMPO radical. Kinetic studies carried out with TEMPO-H(D) reveal second-order behavior, kH = 0.5, kD = 0.08 M-1 s-1 (THF, -80 °C); thus, the hydrogen/deuterium kinetic isotope effect (KIE) = 6, consistent with H-atom abstraction by S being the rate-determining step. This appears to be the first case where experimentally derived thermodynamics lead to a ferric heme hydroperoxide OO-H BDFE determination, that FeIII-OOH species being formed via HAT reactivity of the partner ferric heme superoxide complex.
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Affiliation(s)
- Hyun Kim
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Patrick J Rogler
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Savita K Sharma
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Andrew W Schaefer
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Edward I Solomon
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Kenneth D Karlin
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
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21
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Chulakova DR, Pradipta AR, Lodochnikova OA, Kuznetsov DR, Bulygina KS, Smirnov IS, Usachev KS, Latypova LZ, Kurbangalieva AR, Tanaka K. Facile Access to Optically Active 2,6-Dialkyl-1,5-Diazacyclooctanes. Chem Asian J 2019; 14:4048-4054. [PMID: 31381243 DOI: 10.1002/asia.201900938] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/01/2019] [Indexed: 11/11/2022]
Abstract
The chiral substituted 1,5-diazacyclooctane (1,5-DACO) is of considerable importance and has attracted attention from a wide range of fields due to their unique chemical and biological properties. Despite the application potential, further study has not been optimized due to difficulties in their synthetic accessibility. Here, we report that the 1,5-DACO bearing a chiral auxiliary obtained from the formal [4+4] cycloaddition of N-alkyl-α,β-unsaturated imines can be further derivatized by nucleophilic alkylation to give various chiral substituted 1,5-DACO derivatives. The removal of the chiral auxiliary was effectively carried out using hydrogenation over Pearlman's catalyst. This methodology allows the production of a broad range of unprecedented optically active 2,6-dialkyl-1,5-DACO, which could not be accessed by other methods.
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Affiliation(s)
- Dilyara R Chulakova
- Biofunctional Chemistry Laboratory, Alexander Butlerov Institute of Chemistry, Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia
| | - Ambara R Pradipta
- Biofunctional Synthetic Chemistry Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Olga A Lodochnikova
- Biofunctional Chemistry Laboratory, Alexander Butlerov Institute of Chemistry, Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia.,Arbuzov Institute of Organic and Physical, Chemistry, FRC Kazan Scientific Center of RAS, 8 Arbuzov Street, Kazan, 420088, Russia
| | - Danil R Kuznetsov
- Biofunctional Chemistry Laboratory, Alexander Butlerov Institute of Chemistry, Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia
| | - Kseniya S Bulygina
- Arbuzov Institute of Organic and Physical, Chemistry, FRC Kazan Scientific Center of RAS, 8 Arbuzov Street, Kazan, 420088, Russia
| | - Ivan S Smirnov
- Biofunctional Chemistry Laboratory, Alexander Butlerov Institute of Chemistry, Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia
| | - Konstantin S Usachev
- NMR Laboratory, Institute of Physics, Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia
| | - Liliya Z Latypova
- Biofunctional Chemistry Laboratory, Alexander Butlerov Institute of Chemistry, Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia
| | - Almira R Kurbangalieva
- Biofunctional Chemistry Laboratory, Alexander Butlerov Institute of Chemistry, Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia
| | - Katsunori Tanaka
- Biofunctional Chemistry Laboratory, Alexander Butlerov Institute of Chemistry, Kazan Federal University, 18 Kremlyovskaya Street, Kazan, 420008, Russia.,Biofunctional Synthetic Chemistry Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
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22
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Zhang S, Zhao L. A merged copper(I/II) cluster isolated from Glaser coupling. Nat Commun 2019; 10:4848. [PMID: 31649254 PMCID: PMC6813345 DOI: 10.1038/s41467-019-12889-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 10/08/2019] [Indexed: 12/04/2022] Open
Abstract
Ubiquitous copper-oxygen species are pivotal in enabling multifarious oxidation reactions in biological and chemical transformations. We herein construct a macrocycle-protected mixed-valence cluster [(tBuC≡CCuI3)-(μ2-OH)-CuII] by merging a copper acetylide cluster with a copper-oxygen moiety formed in Glaser coupling. This merged Cu(I/II) cluster shows remarkably strong oxidation capacity, whose reduction potential is among the most positive for Cu(II) and even comparable with some Cu(III) species. Consequently, the cluster exhibits high hydrogen atom transfer (HAT) reactivity with inert hydrocarbons. In contrast, the degraded [CuII-(μ2-OH)-CuII] embedded in a small macrocyclic homologue shows no HAT reactivity. Theoretical calculations indicate that the strong oxidation ability of Cu(II) in [(tBuC≡CCuI3)-(μ2-OH)-CuII] is mainly ascribed to the uneven charge distribution of Cu(I) ions in the tBuC≡CCuI3 unit because of significant [dCu(I) → π*(C≡C)] back donation. The present study on in situ formed metal clusters opens a broad prospect for mechanistic studies of Cu-based catalytic reactions. Copper-oxygen species in organometallic complexes and enzymes are involved in many oxidation reactions. Here, the authors synthesize a macrocycle-protected mixed valence Cu(I/II) cluster with an unusually strong oxidation capacity and apply it to hydrogen atom transfer reactions with inert hydrocarbons.
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Affiliation(s)
- Siqi Zhang
- Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Liang Zhao
- Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China.
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23
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Will J, Würtele C, Becker J, Walter O, Schindler S. Synthesis, crystal structures and reactivity towards dioxygen of copper(I) complexes with tripodal aliphatic amine ligands. Polyhedron 2019. [DOI: 10.1016/j.poly.2019.07.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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24
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Lin YH, Cramer HH, van Gastel M, Tsai YH, Chu CY, Kuo TS, Lee IR, Ye S, Bill E, Lee WZ. Mononuclear Manganese(III) Superoxo Complexes: Synthesis, Characterization, and Reactivity. Inorg Chem 2019; 58:9756-9765. [PMID: 31328507 PMCID: PMC6685055 DOI: 10.1021/acs.inorgchem.9b00767] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Metal-superoxo species are typically proposed as key intermediates in the catalytic cycle of dioxygen activation by metalloenzymes involving different transition metal cofactors. In this regard, while a series of Fe-, Co-, and Ni-superoxo complexes have been reported to date, well-defined Mn-superoxo complexes remain rather rare. Herein, we report two mononuclear MnIII-superoxo species, Mn(BDPP)(O2•-) (2, H2BDPP = 2,6-bis((2-(S)-diphenylhydroxylmethyl-1-pyrrolidinyl)methyl)pyridine) and Mn(BDPBrP)(O2•-) (2', H2BDPBrP = 2,6-bis((2-(S)-di(4-bromo)phenylhydroxyl-methyl-1-pyrrolidinyl)methyl)pyridine), synthesized by bubbling O2 into solutions of their MnII precursors, Mn(BDPP) (1) and Mn(BDPBrP) (1'), at -80 °C. A combined spectroscopic (resonance Raman and electron paramagnetic resonance (EPR) spectroscopy) and computational study evidence that both complexes contain a high-spin MnIII center (SMn = 2) antiferromagnetically coupled to a superoxo radical ligand (SOO• = 1/2), yielding an overall S = 3/2 ground state. Complexes 2 and 2' were shown to be capable of abstracting a H atom from 2,2,6,6-tetramethyl-1-hydroxypiperidine (TEMPO-H) to form MnIII-hydroperoxo species, Mn(BDPP)(OOH) (5) and Mn(BDPBrP)(OOH) (5'). Complexes 5 and 5' can be independently prepared by the reactions of the isolated MnIII-aqua complexes, [Mn(BDPP)(H2O)]OTf (6) and [Mn(BDPBrP)(H2O)]OTf (6'), with H2O2 in the presence of NEt3. The parallel-mode EPR measurements established a high-spin S = 2 ground state for 5 and 5'.
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Affiliation(s)
| | - Hanna Hinrika Cramer
- Max-Planck-Institut für Chemische Energiekonversion , Mülheim an der Ruhr D-45470 , Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung , Mülheim an der Ruhr D-45470 , Germany
| | | | | | | | | | - Shengfa Ye
- Max-Planck-Institut für Kohlenforschung , Mülheim an der Ruhr D-45470 , Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion , Mülheim an der Ruhr D-45470 , Germany
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25
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Alwan KB, Welch EF, Arias RJ, Gambill BF, Blackburn NJ. Rational Design of a Histidine-Methionine Site Modeling the M-Center of Copper Monooxygenases in a Small Metallochaperone Scaffold. Biochemistry 2019; 58:3097-3108. [PMID: 31243953 DOI: 10.1021/acs.biochem.9b00312] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mononuclear copper monooxygenases peptidylglycine monooxygenase (PHM) and dopamine β-monooxygenase (DBM) catalyze the hydroxylation of high energy C-H bonds utilizing a pair of chemically distinct copper sites (CuH and CuM) separated by 11 Å. In earlier work, we constructed single-site PHM variants that were designed to allow the study of the M- and H-centers independently in order to place their reactivity sequentially along the catalytic pathway. More recent crystallographic studies suggest that these single-site variants may not be truly representative of the individual active sites. In this work, we describe an alternative approach that uses a rational design to construct an artificial PHM model in a small metallochaperone scaffold. Using site-directed mutagenesis, we constructed variants that provide a His2Met copper-binding ligand set that mimics the M-center of PHM. The results show that the model accurately reproduces the chemical and spectroscopic properties of the M-center, including details of the methionine coordination, and the properties of Cu(I) and Cu(II) states in the presence of endogenous ligands such as CO and azide. The rate of reduction of the Cu(II) form of the model by the chromophoric reductant N,N'-dimethyl phenylenediamine (DMPD) has been compared with that of the PHM M-center, and the reaction chemistry of the Cu(I) forms with molecular oxygen has also been explored, revealing an unusually low reactivity toward molecular oxygen. This latter finding emphasizes the importance of substrate triggering of oxygen reactivity and implies that the His2Met ligand set, while necessary, is insufficient on its own to activate oxygen in these enzyme systems.
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Affiliation(s)
- Katherine B Alwan
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Evan F Welch
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Renee J Arias
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Ben F Gambill
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Ninian J Blackburn
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
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26
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Bailey WD, Dhar D, Cramblitt AC, Tolman WB. Mechanistic Dichotomy in Proton-Coupled Electron-Transfer Reactions of Phenols with a Copper Superoxide Complex. J Am Chem Soc 2019; 141:5470-5480. [PMID: 30907590 DOI: 10.1021/jacs.9b00466] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The kinetics and mechanism(s) of the reactions of [K(Krypt)][LCuO2] (Krypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane, L = a bis(arylcarboxamido)pyridine ligand) with 2,2,6,6-tetramethylpiperdine- N-hydroxide (TEMPOH) and the para-substituted phenols XArOH (X = para substituent NO2, CF3, Cl, H, Me, tBu, OMe, or NMe2) at low temperatures were studied. The reaction with TEMPOH occurs rapidly ( k = 35.4 ± 0.3 M-1 s-1) by second-order kinetics to yield TEMPO• and [LCuOOH]- on the basis of electron paramagnetic resonance spectroscopy, the production of H2O2 upon treatment with protic acid, and independent preparation from reaction of [NBu4][LCuOH] with H2O2 ( Keq = 0.022 ± 0.007 for the reverse reaction). The reactions with XArOH also follow second-order kinetics, and analysis of the variation of the k values as a function of phenol properties (Hammett σ parameter, O-H bond dissociation free energy, p Ka, E1/2) revealed a change in mechanism across the series, from proton transfer/electron transfer for X = NO2, CF3, Cl to concerted-proton/electron transfer (or hydrogen-atom transfer) for X = OMe, NMe2 (data for X = H, Me, tBu are intermediate between the extremes). Thermodynamic analysis and comparisons to previous results for LCuOH, a different copper-oxygen intermediate with the same supporting ligand, and literature for other [CuO2]+ complexes reveal significant differences in proton-coupled electron-transfer mechanisms that have implications for understanding oxidation catalysis by copper-containing enzymes and abiological catalysts.
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Affiliation(s)
- Wilson D Bailey
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive, Campus Box 1134 , St. Louis , Missouri 63130-4899 , United States
| | - Debanjan Dhar
- Department of Chemistry and Center for Metals in Biocatalysis , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Anna C Cramblitt
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive, Campus Box 1134 , St. Louis , Missouri 63130-4899 , United States
| | - William B Tolman
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive, Campus Box 1134 , St. Louis , Missouri 63130-4899 , United States.,Department of Chemistry and Center for Metals in Biocatalysis , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
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27
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Noh H, Cho J. Synthesis, characterization and reactivity of non-heme 1st row transition metal-superoxo intermediates. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2018.12.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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28
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Cupric-superoxide complex that induces a catalytic aldol reaction-type C–C bond formation. Commun Chem 2019. [DOI: 10.1038/s42004-019-0115-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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29
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Sacramento JJD, Goldberg DP. The hydrogen atom transfer reactivity of a porphyrinoid cobalt superoxide complex. Chem Commun (Camb) 2019; 55:913-916. [PMID: 30608073 DOI: 10.1039/c8cc08453j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The H-atom transfer (HAT) reactivity of a corrolazine cobalt superoxide with weak O-H and N-H substrates has been demonstrated. Kinetic analysis shows relatively fast rates of HAT with diphenylhydrazine (DPH). A kinetic isotope effect (KIE) and Eyring activation parameters are consistent with an HAT mechanism.
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Affiliation(s)
- Jireh Joy D Sacramento
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA.
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30
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Adam SM, Wijeratne GB, Rogler PJ, Diaz DE, Quist DA, Liu JJ, Karlin KD. Synthetic Fe/Cu Complexes: Toward Understanding Heme-Copper Oxidase Structure and Function. Chem Rev 2018; 118:10840-11022. [PMID: 30372042 PMCID: PMC6360144 DOI: 10.1021/acs.chemrev.8b00074] [Citation(s) in RCA: 145] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heme-copper oxidases (HCOs) are terminal enzymes on the mitochondrial or bacterial respiratory electron transport chain, which utilize a unique heterobinuclear active site to catalyze the 4H+/4e- reduction of dioxygen to water. This process involves a proton-coupled electron transfer (PCET) from a tyrosine (phenolic) residue and additional redox events coupled to transmembrane proton pumping and ATP synthesis. Given that HCOs are large, complex, membrane-bound enzymes, bioinspired synthetic model chemistry is a promising approach to better understand heme-Cu-mediated dioxygen reduction, including the details of proton and electron movements. This review encompasses important aspects of heme-O2 and copper-O2 (bio)chemistries as they relate to the design and interpretation of small molecule model systems and provides perspectives from fundamental coordination chemistry, which can be applied to the understanding of HCO activity. We focus on recent advancements from studies of heme-Cu models, evaluating experimental and computational results, which highlight important fundamental structure-function relationships. Finally, we provide an outlook for future potential contributions from synthetic inorganic chemistry and discuss their implications with relevance to biological O2-reduction.
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Affiliation(s)
- Suzanne M. Adam
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Gayan B. Wijeratne
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Patrick J. Rogler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Daniel E. Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David A. Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Jeffrey J. Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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31
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Paria S, Ohta T, Morimoto Y, Sugimoto H, Ogura T, Itoh S. Structure and Reactivity of Copper Complexes Supported by a Bulky Tripodal N
4
Ligand: Copper(I)/Dioxygen Reactivity and Formation of a Hydroperoxide Copper(II) Complex. Z Anorg Allg Chem 2018. [DOI: 10.1002/zaac.201800083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sayantan Paria
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamada‐oka 565–0871 Osaka Suita Japan
- Graduate School of Life Science Department of Chemistry Indian Institute of Technology Delhi Hauz Khas 110016 New Delhi India
| | - Takehiro Ohta
- Picobiology Institute Graduate School of Life Science University of Hyogo RSC‐UH LP Center 679–5148 Hyogo Koto 1‐1‐1, Sayo‐cho, Sayo‐gun Japan
| | - Yuma Morimoto
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamada‐oka 565–0871 Osaka Suita Japan
| | - Hideki Sugimoto
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamada‐oka 565–0871 Osaka Suita Japan
| | - Takashi Ogura
- Picobiology Institute Graduate School of Life Science University of Hyogo RSC‐UH LP Center 679–5148 Hyogo Koto 1‐1‐1, Sayo‐cho, Sayo‐gun Japan
| | - Shinobu Itoh
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamada‐oka 565–0871 Osaka Suita Japan
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32
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Dereli B, Momeni MR, Cramer CJ. Density Functional Modeling of Ligand Effects on Electronic Structure and C–H Bond Activation Activity of Copper(III) Hydroxide Compounds. Inorg Chem 2018; 57:9807-9813. [DOI: 10.1021/acs.inorgchem.8b01530] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Büsra Dereli
- Department of Chemistry, Minnesota Supercomputing Institute, and Chemical Theory Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Mohammad R. Momeni
- Department of Chemistry, Minnesota Supercomputing Institute, and Chemical Theory Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Christopher J. Cramer
- Department of Chemistry, Minnesota Supercomputing Institute, and Chemical Theory Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
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33
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Pandey B, Ray K, Rajaraman G. Structure, Bonding, Reactivity and Spectral Features of Putative NiIII
=O Species: A Theoretical Perspective. Z Anorg Allg Chem 2018. [DOI: 10.1002/zaac.201800122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Bhawana Pandey
- Department of Chemistry; Indian Institute of Technology Bombay; 400 076 Powai India
| | - Kallol Ray
- Institut fár Chemie; Humboldt-Universität zu Berlin; Brook-Taylor-Straße 2 12489 Berlin Germany
| | - Gopalan Rajaraman
- Department of Chemistry; Indian Institute of Technology Bombay; 400 076 Powai India
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34
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Paria S, Morimoto Y, Ohta T, Okabe S, Sugimoto H, Ogura T, Itoh S. Copper(I)–Dioxygen Reactivity in the Isolated Cavity of a Nanoscale Molecular Architecture. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Sayantan Paria
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamadaoka 565‐0871 Suita Osaka Japan
| | - Yuma Morimoto
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamadaoka 565‐0871 Suita Osaka Japan
| | - Takehiro Ohta
- Picobiology Institute Graduate School of Life Science University of Hyogo Koto 1‐1‐1 679‐5148 Sayo‐cho Sayo‐gun, Hyogo Japan
| | - Shinsuke Okabe
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamadaoka 565‐0871 Suita Osaka Japan
| | - Hideki Sugimoto
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamadaoka 565‐0871 Suita Osaka Japan
| | - Takashi Ogura
- Picobiology Institute Graduate School of Life Science University of Hyogo Koto 1‐1‐1 679‐5148 Sayo‐cho Sayo‐gun, Hyogo Japan
| | - Shinobu Itoh
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamadaoka 565‐0871 Suita Osaka Japan
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35
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Meier KK, Jones SM, Kaper T, Hansson H, Koetsier MJ, Karkehabadi S, Solomon EI, Sandgren M, Kelemen B. Oxygen Activation by Cu LPMOs in Recalcitrant Carbohydrate Polysaccharide Conversion to Monomer Sugars. Chem Rev 2018; 118:2593-2635. [PMID: 29155571 PMCID: PMC5982588 DOI: 10.1021/acs.chemrev.7b00421] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Natural carbohydrate polymers such as starch, cellulose, and chitin provide renewable alternatives to fossil fuels as a source for fuels and materials. As such, there is considerable interest in their conversion for industrial purposes, which is evidenced by the established and emerging markets for products derived from these natural polymers. In many cases, this is achieved via industrial processes that use enzymes to break down carbohydrates to monomer sugars. One of the major challenges facing large-scale industrial applications utilizing natural carbohydrate polymers is rooted in the fact that naturally occurring forms of starch, cellulose, and chitin can have tightly packed organizations of polymer chains with low hydration levels, giving rise to crystalline structures that are highly recalcitrant to enzymatic degradation. The topic of this review is oxidative cleavage of carbohydrate polymers by lytic polysaccharide mono-oxygenases (LPMOs). LPMOs are copper-dependent enzymes (EC 1.14.99.53-56) that, with glycoside hydrolases, participate in the degradation of recalcitrant carbohydrate polymers. Their activity and structural underpinnings provide insights into biological mechanisms of polysaccharide degradation.
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Affiliation(s)
- Katlyn K. Meier
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Stephen M. Jones
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Thijs Kaper
- DuPont Industrial Biosciences, 925 Page Mill Road, Palo Alto, California 94304, United States
| | - Henrik Hansson
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden
| | - Martijn J. Koetsier
- DuPont Industrial Biosciences, Netherlands, Nieuwe Kanaal 7-S, 6709 PA Wageningen, The Netherlands
| | - Saeid Karkehabadi
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden
| | - Bradley Kelemen
- DuPont Industrial Biosciences, 925 Page Mill Road, Palo Alto, California 94304, United States
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36
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Snider VG, Pella BJ, Mukherjee A. Synthesis, characterization, and reactivity of copper complexes supported by the TPMEN ligand framework. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.09.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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37
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Geometric effects on O O bond scission of copper(II)-alkylperoxide complexes. J Inorg Biochem 2017; 177:375-383. [DOI: 10.1016/j.jinorgbio.2017.08.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 08/01/2017] [Accepted: 08/21/2017] [Indexed: 11/20/2022]
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38
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Iovan DA, Wrobel AT, McClelland AA, Scharf AB, Edouard GA, Betley TA. Reactivity of a stable copper-dioxygen complex. Chem Commun (Camb) 2017; 53:10306-10309. [PMID: 28869644 PMCID: PMC5605793 DOI: 10.1039/c7cc05014c] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We report the isolation of a room temperature stable dipyrromethene Cu(O2) complex featuring a side-on O2 coordination. Reactivity studies highlight the unique ability of the dioxygen adduct for both hydrogen-atom abstraction and acid/base chemistry towards phenols, demonstrating that side-on superoxide species can be reactive entities.
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Affiliation(s)
- Diana A Iovan
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138, USA.
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39
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Devi T, Lee Y, Jung J, Sankaralingam M, Nam W, Fukuzumi S. A Chromium(III)‐Superoxo Complex as a Three‐Electron Oxidant with a Large Tunneling Effect in Multi‐Electron Oxidation of NADH Analogues. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611709] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Tarali Devi
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Yong‐Min Lee
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Jieun Jung
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | | | - Wonwoo Nam
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
- State Key Laboratory for Oxo Synthesis and Selective Oxidation Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou 730000 China
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
- Faculty of Science and Engineering SENTAN Japan Science and Technology Agency (JST) Meijo University Nagoya, Aichi 468-8502 Japan
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40
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Devi T, Lee YM, Jung J, Sankaralingam M, Nam W, Fukuzumi S. A Chromium(III)-Superoxo Complex as a Three-Electron Oxidant with a Large Tunneling Effect in Multi-Electron Oxidation of NADH Analogues. Angew Chem Int Ed Engl 2017; 56:3510-3515. [PMID: 28266771 DOI: 10.1002/anie.201611709] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/15/2017] [Indexed: 11/06/2022]
Abstract
Metal-superoxo species are involved in a variety of enzymatic oxidation reactions, and multi-electron oxidation of substrates is frequently observed in those enzymatic reactions. A CrIII -superoxo complex, [CrIII (O2 )(TMC)(Cl)]+ (1; TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), is described that acts as a novel three-electron oxidant in the oxidation of dihydronicotinamide adenine dinucleotide (NADH) analogues. In the reactions of 1 with NADH analogues, a CrIV -oxo complex, [CrIV (O)(TMC)(Cl)]+ (2), is formed by a heterolytic O-O bond cleavage of a putative CrII -hydroperoxo complex, [CrII (OOH)(TMC)(Cl)], which is generated by hydride transfer from NADH analogues to 1. The comparison of the reactivity of NADH analogues with 1 and p-chloranil (Cl4 Q) indicates that oxidation of NADH analogues by 1 proceeds by proton-coupled electron transfer with a very large tunneling effect (for example, with a kinetic isotope effect of 470 at 233 K), followed by rapid electron transfer.
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Affiliation(s)
- Tarali Devi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea
| | - Jieun Jung
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea
| | | | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea.,State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea.,Faculty of Science and Engineering, SENTAN Japan Science and Technology Agency (JST), Meijo University, Nagoya, Aichi, 468-8502, Japan
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41
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Elwell CE, Gagnon NL, Neisen BD, Dhar D, Spaeth AD, Yee GM, Tolman WB. Copper-Oxygen Complexes Revisited: Structures, Spectroscopy, and Reactivity. Chem Rev 2017; 117:2059-2107. [PMID: 28103018 PMCID: PMC5963733 DOI: 10.1021/acs.chemrev.6b00636] [Citation(s) in RCA: 445] [Impact Index Per Article: 63.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A longstanding research goal has been to understand the nature and role of copper-oxygen intermediates within copper-containing enzymes and abiological catalysts. Synthetic chemistry has played a pivotal role in highlighting the viability of proposed intermediates and expanding the library of known copper-oxygen cores. In addition to the number of new complexes that have been synthesized since the previous reviews on this topic in this journal (Mirica, L. M.; Ottenwaelder, X.; Stack, T. D. P. Chem. Rev. 2004, 104, 1013-1046 and Lewis, E. A.; Tolman, W. B. Chem. Rev. 2004, 104, 1047-1076), the field has seen significant expansion in the (1) range of cores synthesized and characterized, (2) amount of mechanistic work performed, particularly in the area of organic substrate oxidation, and (3) use of computational methods for both the corroboration and prediction of proposed intermediates. The scope of this review has been limited to well-characterized examples of copper-oxygen species but seeks to provide a thorough picture of the spectroscopic characteristics and reactivity trends of the copper-oxygen cores discussed.
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Affiliation(s)
- Courtney E Elwell
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Nicole L Gagnon
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Benjamin D Neisen
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Debanjan Dhar
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Andrew D Spaeth
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Gereon M Yee
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - William B Tolman
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
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42
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Kline CD, Blackburn NJ. Substrate-Induced Carbon Monoxide Reactivity Suggests Multiple Enzyme Conformations at the Catalytic Copper M-Center of Peptidylglycine Monooxygenase. Biochemistry 2016; 55:6652-6661. [PMID: 27933800 DOI: 10.1021/acs.biochem.6b00845] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present study uses CO as a surrogate for oxygen to probe how substrate binding triggers oxygen activation in peptidylglycine monooygenase (PHM). Infrared stretching frequencies (ν(C ≡ O)) of the carbonyl (CO) adducts of copper proteins are sensitive markers of Cu(I) coordination and are useful in probing oxygen reactivity because the electronic properties of O2 and CO are similar. The carbonyl chemistry has been explored using PHM WT and a number of active site variants in the absence and presence of peptidyl substrates. We have determined that upon carbonylation (i) a major CO band at 2092 cm-1 and a second minor CO band at 2063 cm-1 are observed in the absence of peptide substrate Ac-YVG; (ii) the presence of peptide substrate amplifies the minor CO band and causes it to partially interconvert with the CO band at 2092 cm-1; (iii) the substrate-induced CO band is associated with a second conformer at CuM; and (iv) the CuH-site mutants, which are inactive, fail to generate any substrate-induced CO bands. The total intensity of both bands is constant, suggesting that the Cu(I)M-site partitions between the two carbonylated enzyme states. Together, these data provide evidence for two conformers at CuM, one of which is induced by binding of the peptide substrate with the implication that this represents the conformation that also allows binding and activation of O2.
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Affiliation(s)
- Chelsey D Kline
- Institute of Environmental Health, Oregon Health and Science University , 3181 S.W. Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Ninian J Blackburn
- Institute of Environmental Health, Oregon Health and Science University , 3181 S.W. Sam Jackson Park Road, Portland, Oregon 97239, United States
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43
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Coordination and redox properties of copper interaction with α-synuclein. J Inorg Biochem 2016; 163:292-300. [DOI: 10.1016/j.jinorgbio.2016.04.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 03/11/2016] [Accepted: 04/04/2016] [Indexed: 11/23/2022]
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44
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Cowley RE, Cirera J, Qayyum MF, Rokhsana D, Hedman B, Hodgson KO, Dooley DM, Solomon EI. Structure of the Reduced Copper Active Site in Preprocessed Galactose Oxidase: Ligand Tuning for One-Electron O 2 Activation in Cofactor Biogenesis. J Am Chem Soc 2016; 138:13219-13229. [PMID: 27626829 DOI: 10.1021/jacs.6b05792] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Galactose oxidase (GO) is a copper-dependent enzyme that accomplishes 2e- substrate oxidation by pairing a single copper with an unusual cysteinylated tyrosine (Cys-Tyr) redox cofactor. Previous studies have demonstrated that the post-translational biogenesis of Cys-Tyr is copper- and O2-dependent, resulting in a self-processing enzyme system. To investigate the mechanism of cofactor biogenesis in GO, the active-site structure of Cu(I)-loaded GO was determined using X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy, and density-functional theory (DFT) calculations were performed on this model. Our results show that the active-site tyrosine lowers the Cu potential to enable the thermodynamically unfavorable 1e- reduction of O2, and the resulting Cu(II)-O2•- is activated toward H atom abstraction from cysteine. The final step of biogenesis is a concerted reaction involving coordinated Tyr ring deprotonation where Cu(II) coordination enables formation of the Cys-Tyr cross-link. These spectroscopic and computational results highlight the role of the Cu(I) in enabling O2 activation by 1e- and the role of the resulting Cu(II) in enabling substrate activation for biogenesis.
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Affiliation(s)
- Ryan E Cowley
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Jordi Cirera
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Munzarin F Qayyum
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Dalia Rokhsana
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Britt Hedman
- Department of Chemistry, Stanford University , Stanford, California 94305, United States.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University , Menlo Park, California 94025, United States
| | - Keith O Hodgson
- Department of Chemistry, Stanford University , Stanford, California 94305, United States.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University , Menlo Park, California 94025, United States
| | - David M Dooley
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States.,University of Rhode Island , Kingston, Rhode Island 02881, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University , Stanford, California 94305, United States.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University , Menlo Park, California 94025, United States
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45
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Maji RC, Das PP, Mishra S, Bhandari A, Maji M, Patra AK. Electron transfer mechanism of catalytic superoxide dismutation via Cu(ii/i) complexes: evidence of cupric-superoxo/-hydroperoxo species. Dalton Trans 2016; 45:11898-910. [PMID: 27383660 DOI: 10.1039/c6dt02220k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To understand the electron transfer mechanisms (outer versus inner sphere) of catalytic superoxide dismutation via a Cu(ii/i) redox couple such as occur in the enzyme copper-zinc superoxide dismutase, the Cu(ii/i) complexes [(L1)2Cu](ClO4)2·CH3CN, (1·CH3CN) and [(L1)2Cu](ClO4), (2) supported by a bis-N2Sthioether ligand, 2-pyridyl-N-(2'-methylthiophenyl)methyleneimine (L1) have been synthesized and structurally characterised. Both 1 and 2 display the same cyclic voltammogram (CV) featuring a quasireversible response at E1/2 = +0.33 V vs. SCE that falls in the SOD potential window of -0.04 V to +0.99 V. These complexes catalytically dismutate superoxide radicals at 298 K in aqueous medium (the IC50 for 1 is 2.15 μM). Electronic absorption spectra (233 K and 298 K), FTIR, ESI mass spectra, CV (233 K and 298 K) and DFT calculations collectively indicate formation of [(L1)2Cu(O2˙(-))](+), [(L1)2Cu(O2(2-))] and [(L1)2Cu(OOH(-))](+) species and help to elucidate the electron transfer mechanism for the SOD function of 1 and 2. Once O2˙(-) binds to Cu(II) (evident at 233 K), the first step of the catalytic cycle (Cu(II) + O2˙(-)→ Cu(I) + O2) does not follow but the second step (Cu(I) + O2˙(-) + 2H(+)→ H2O2 + Cu(II)) does follow. Therefore, the catalytic disproportionation of superoxide radicals via1 and 2 at 298 K indicates that the first and second steps of the catalytic cycle proceed through outer and inner sphere electron transfer mechanisms, respectively. Feasibility of the first step to occur in pure aprotic solvent (where 18-crown-6-ether is used to solubilise KO2) was tested and also supports the same notion of the electron transfer mechanisms as stated above.
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Affiliation(s)
- Ram Chandra Maji
- Department of Chemistry, National Institute of Technology Durgapur, Mahatma Gandhi Avenue, Durgapur 713209, West Bengal, India.
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46
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Ure AD, Lázaro IA, Cotter M, McDonald AR. Synthesis and characterisation of a mesocyclic tripodal triamine ligand. Org Biomol Chem 2016; 14:483-494. [DOI: 10.1039/c5ob01556a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The preparation and characterisation of mesocyclic polydentate amine ligands is described. The novel tridentate ligands will be employed in the stabilisation of highly reactive high-valent oxidants.
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Affiliation(s)
- Andrew D. Ure
- School of Chemistry and CRANN/AMBER Nanoscience Institute
- Trinity College Dublin
- The University of Dublin
- College Green
- Dublin 2
| | - Isabel Abánades Lázaro
- School of Chemistry and CRANN/AMBER Nanoscience Institute
- Trinity College Dublin
- The University of Dublin
- College Green
- Dublin 2
| | - Michelle Cotter
- School of Chemistry and CRANN/AMBER Nanoscience Institute
- Trinity College Dublin
- The University of Dublin
- College Green
- Dublin 2
| | - Aidan R. McDonald
- School of Chemistry and CRANN/AMBER Nanoscience Institute
- Trinity College Dublin
- The University of Dublin
- College Green
- Dublin 2
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47
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Saracini C, Ohkubo K, Suenobu T, Meyer GJ, Karlin KD, Fukuzumi S. Laser-Induced Dynamics of Peroxodicopper(II) Complexes Vary with the Ligand Architecture. One-Photon Two-Electron O2 Ejection and Formation of Mixed-Valent Cu(I)Cu(II)-Superoxide Intermediates. J Am Chem Soc 2015; 137:15865-74. [PMID: 26651492 DOI: 10.1021/jacs.5b10177] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Photoexcitation of end-on trans-μ-1,2-peroxodicopper(II) complex [(tmpa)2Cu(II)2(O2)](2+) (1) (λmax = 525 and 600 nm) and side-on μ-η(2):η(2)-peroxodicopper(II) complexes [(N5)Cu(II)2(O2)](2+) (2) and [(N3)Cu(II)2(O2)](2+) (3) at -80 °C in acetone led to one-photon two-electron peroxide-to-dioxygen oxidation chemistry (O2(2-) + hν → O2 + 2e(-)). Interestingly, light excitation of 2 and 3 (having side-on μ-η(2):η(2)-peroxo ligation) led to release of dioxygen, while photoexcitation of 1 (having an end-on trans-1,2-peroxo geometry) did not, even though spectroscopic studies revealed that both reactions proceeded through previously unknown mixed-valent superoxide species: [Cu(II)(O2(•-))Cu(I)](2+) (λmax = 685-740 nm). For 1, this intermediate underwent further fast intramolecular electron transfer to yield an "O2-caged" dicopper(I) adduct, Cu(I)2-O2, and a barrierless stepwise back electron transfer to regenerate 1 occurred. Femtosecond laser excitation of 2 and 3 under the same conditions still led to [Cu(II)(O2(•-))Cu(I)](2+) intermediates that, instead, underwent O2 release with a quantum yield of 0.14 ± 0.1 for 3. Such remarkable differences in reaction pathways likely result from the well-known ligand-derived stability of 2 and 3 vs 1 indicated by ligand-Cu(II/I) redox potentials; (N5)Cu(I) and (N3)Cu(I) complexes are far more stable than (tmpa)Cu(I) species. The fast Cu(I)2/O2 rebinding kinetics was also measured after photoexcitation of 2 and 3, with the results closely tracking those known for the dicopper proteins hemocyanin and tyrosinase, for which the synthetic dicopper(I) precursors [(N5)Cu(I)2](2+) and [(N3)Cu(I)2](2+) and their dioxygen adducts serve as models. The biological relevance of the present findings is discussed, including the potential impact on the solar water splitting process.
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Affiliation(s)
- Claudio Saracini
- Department of Chemistry, The Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Kei Ohkubo
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology Agency (JST) , Suita, Osaka 565-0871, Japan.,Department of Chemistry and Nano Science, Ewha Womans University , Seoul 120-750, Korea
| | - Tomoyoshi Suenobu
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology Agency (JST) , Suita, Osaka 565-0871, Japan
| | - Gerald J Meyer
- Department of Chemistry, The Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Kenneth D Karlin
- Department of Chemistry, The Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology Agency (JST) , Suita, Osaka 565-0871, Japan.,Department of Chemistry and Nano Science, Ewha Womans University , Seoul 120-750, Korea.,Faculty of Science and Engineering, Meijo University, ALCA and SENTAN, Japan Science and Technology Agency (JST) , Nagoya, Aichi 468-0073, Japan
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48
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Itoh S. Developing mononuclear copper-active-oxygen complexes relevant to reactive intermediates of biological oxidation reactions. Acc Chem Res 2015; 48:2066-74. [PMID: 26086527 DOI: 10.1021/acs.accounts.5b00140] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Active-oxygen species generated on a copper complex play vital roles in several biological and chemical oxidation reactions. Recent attention has been focused on the reactive intermediates generated at the mononuclear copper active sites of copper monooxygenases such as dopamine β-monooxygenase (DβM), tyramine β-monooxygenase (TβM), peptidylglycine-α-hydroxylating monooxygenase (PHM), and polysaccharide monooxygenases (PMO). In a simple model system, reaction of O2 and a reduced copper(I) complex affords a mononuclear copper(II)-superoxide complex or a copper(III)-peroxide complex, and subsequent H(•) or e(-)/H(+) transfer, which gives a copper(II)-hydroperoxide complex. A more reactive species such as a copper(II)-oxyl radical type species could be generated via O-O bond cleavage of the peroxide complex. However, little had been explored about the chemical properties and reactivity of the mononuclear copper-active-oxygen complexes due to the lack of appropriate model compounds. Thus, a great deal of effort has recently been made to develop efficient ligands that can stabilize such reactive active-oxygen complexes in synthetic modeling studies. In this Account, I describe our recent achievements of the development of a mononuclear copper(II)-(end-on)superoxide complex using a simple tridentate ligand consisting of an eight-membered cyclic diamine with a pyridylethyl donor group. The superoxide complex exhibits a similar structure (four-coordinate tetrahedral geometry) and reactivity (aliphatic hydroxylation) to those of a proposed reactive intermediate of copper monooxygenases. Systematic studies based on the crystal structures of copper(I) and copper(II) complexes of the related tridentate supporting ligands have indicated that the rigid eight-membered cyclic diamine framework is crucial for controlling the geometry and the redox potential, which are prerequisites for the generation of such a unique mononuclear copper(II)-(end-on)superoxide complex. Reactivity of a mononuclear copper(II)-alkylperoxide complex has also been examined to get insights into the intrinsic reactivity of copper(II)-peroxide species, which is usually considered as a sluggish oxidant or just a precursor of copper-oxyl radical type reactive species. However, our studies have unambiguously demonstrated that copper(II)-alkylperoxide complex can be a direct oxidant for C-H bond activation of organic substrates, when the C-H bond activation is coupled with O-O bond cleavage (concerted mechanism). The reactivity studies of these mononuclear copper(II) active-oxygen species (superoxide and alkylperoxide) will provide significantly important insights into the catalytic mechanism of copper monooxygenases as well as copper-catalyzed oxidation reactions in synthetic organic chemistry.
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Affiliation(s)
- Shinobu Itoh
- Department of Material and
Life Science, Division of Advanced Science and Biotechnology, Graduate
School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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49
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Synthesis, characterization, cis-ligand substitution and catalytic alkane hydroxylation by mononuclear nickel(II) complexes stabilized with tetradentate tripodal ligands. Inorganica Chim Acta 2015. [DOI: 10.1016/j.ica.2015.01.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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50
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Ray K, Pfaff FF, Wang B, Nam W. Status of Reactive Non-Heme Metal–Oxygen Intermediates in Chemical and Enzymatic Reactions. J Am Chem Soc 2014; 136:13942-58. [DOI: 10.1021/ja507807v] [Citation(s) in RCA: 351] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kallol Ray
- Department
of Chemistry, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Florian Felix Pfaff
- Department
of Chemistry, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Bin Wang
- Department
of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Wonwoo Nam
- Department
of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
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