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Ghosh S, Tran PN, McElheny D, Perez JJ, Nguyen AI. Peptidic Scaffolds Enable Rapid and Multivariate Secondary Sphere Evolution for an Abiotic Metallocatalyst. Inorg Chem 2022; 61:6679-6687. [PMID: 35446044 DOI: 10.1021/acs.inorgchem.2c00901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Metalloenzymes have benefited from the iterative process of evolution to achieve the precise arrangements of secondary sphere non-covalent interactions that enhance metal-centered catalysis. Iterative synthesis of scaffolds that display complex secondary sphere elements in abiotic systems can be highly challenging and time-intensive. To overcome this synthetic bottleneck, we developed a highly modular and rapid synthetic strategy, leveraging the efficiency of solid-phase peptide synthesis and conformational control afforded by non-canonical residues to construct a ligand platform displaying up to four unique residues of varying electronics and sterics in the secondary coordination sphere. As a proof-of-concept that peptidic secondary sphere can cooperate with the metal complex, we applied this scaffold to a well-known, modestly active C-H oxidizing Fe catalyst to evolve specific non-covalent interactions that is more than double its catalytic activity. Solution-state NMR structures of several catalyst variants suggest that higher activity is correlated with a hydrophobic pocket above the Fe center that may enhance the formation of a catalyst-substrate complex. Above all, we show that peptides are a convenient, highly modular, and structurally defined ligand platform for creating secondary coordination spheres that comprise multiple, diverse functional groups.
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Affiliation(s)
- Sabari Ghosh
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Phuong Nguyen Tran
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Dan McElheny
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Juan J Perez
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Andy I Nguyen
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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2
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Ma Z, Nakatani N, Hada M. Insights into the electronic structure and mechanism of norcarane hydroxylation by OxoMn(V) porphyrin complexes: A density functional theory study. J Comput Chem 2021; 42:1920-1928. [PMID: 34448235 DOI: 10.1002/jcc.26715] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/12/2021] [Accepted: 06/15/2021] [Indexed: 11/05/2022]
Abstract
Norcarane hydroxylation by neutral [PorMn(V)O-L] (L═OH- , F- ) and cationic [PorMn(V)O-L]+ (L═H2 O, imidazole) oxoMn(V) porphyrin complex models has been investigated by density functional theory calculations to better understand the reaction mechanism and electronic structure. We found that the energy barriers of norcarane hydroxylation by cationic oxoMn(V) porphyrin complexes are lower than those by neutral oxoMn(V) porphyrin complexes. This indicates that cationic oxoMn(V) porphyrin complexes enhance norcarane hydroxylation compared with neutral oxoMn(V) porphyrin complexes. According to electronic structure analysis, in the C─H activation step, electron transfer occurs through initial interaction between the σCH and rich-oxygen π(Mn═O) orbitals to form real donor orbitals, followed by transfer to the acceptor π*(Mn═O) orbitals. Moreover, single electron shifts from norcarane (CH) to Mn atom during C─H activation. The positive charge of the cationic complex stabilizes the acceptor orbital more than the donor orbital, reducing the energy gap between these orbitals, thus lowering the reaction barrier.
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Affiliation(s)
- Zhifeng Ma
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Japan
| | - Naoki Nakatani
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Japan
| | - Masahiko Hada
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Japan
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3
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Winter A, Schubert US. Metal‐Terpyridine Complexes in Catalytic Application – A Spotlight on the Last Decade. ChemCatChem 2020. [DOI: 10.1002/cctc.201902290] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Andreas Winter
- Laboratory of Organic and Macromolecular Chemistry (IOMC)Friedrich Schiller University Jena Humboldtstr. 10 07743 Jena Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena) Philosophenweg 7a 07743 Jena Germany
| | - Ulrich S. Schubert
- Laboratory of Organic and Macromolecular Chemistry (IOMC)Friedrich Schiller University Jena Humboldtstr. 10 07743 Jena Germany
- Center for Energy and Environmental Chemistry Jena (CEEC Jena) Philosophenweg 7a 07743 Jena Germany
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4
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Burg F, Bach T. Lactam Hydrogen Bonds as Control Elements in Enantioselective Transition-Metal-Catalyzed and Photochemical Reactions. J Org Chem 2019; 84:8815-8836. [DOI: 10.1021/acs.joc.9b01299] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Finn Burg
- Department of Chemistry and Catalysis Research Center (CRC), Technical University of Munich, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Thorsten Bach
- Department of Chemistry and Catalysis Research Center (CRC), Technical University of Munich, Lichtenbergstrasse 4, 85747 Garching, Germany
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Ricciarelli D, Phung QM, Belpassi L, Harvey JN, Belanzoni P. Understanding the Reactivity of Mn-Oxo Porphyrins for Substrate Hydroxylation: Theoretical Predictions and Experimental Evidence Reconciled. Inorg Chem 2019; 58:7345-7356. [PMID: 31117625 DOI: 10.1021/acs.inorgchem.9b00476] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Mn-oxo porphyrin (MnOP) mechanism for substrate hydroxylation is computationally studied with the aim to better understand reactivity in these systems. Theoretical studies suggest Mn(V)OP species to be very reactive intermediates with thermally accessible reaction barriers represented by low-spin/high-spin-crossover occurring in the Mn(V)OP oxidant, and kinetics for selected Mn(V)OP species indeed find high reactivity. On the other hand, MnOP complexes lead to modest yields in hydroxylation reactions of several different substrates, implying low rate constants and high reaction barriers. The resolution of this inconsistency is very important to understand the reactivity of Mn-oxo porphyrins and to improve the catalytic conditions. In this work we use the toluene hydroxylation by the Mn(V)OP(H2O)+ complex as a case study to gain deep insight into the reaction mechanism. Minimum energy crossing point (MECP) results on the H-abstraction process from toluene indicate a first crossover from a singlet to a triplet spin state of the Mn(V)OP(H2O)+ species with a thermally accessible barrier, followed by a very facile H-abstraction by the triplet complex. Issues concerning (i) the validation of the level of the density functional theory employed (BP86) to describe the singlet-triplet energy gap in the Mn(V)OP(H2O)+ system versus highly accurate DMRG-CASPT2/CC calculations, and (ii) the influence of the axial ligand (X = none, Cl-, CH3CN, OH-, and O2-) on MnOP reactivity, which models the different experimental conditions, are addressed. The ligand trans influence mainly controls the reactivity through the singlet-triplet energy gap modulation, with the porphyrin ruffling distortion also finely tuning it. Finally, a stepwise model for the H-abstraction process is proposed which allows a direct comparison between the calculated and experimentally measured Gibbs free activation energy barriers ( Zhang et al. J. Am. Chem. Soc. 2005 , 127 , 6573 - 6582 ). The low yields in catalysis are shown not to be due to low reactivity of Mn(V).
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Affiliation(s)
| | - Quan Manh Phung
- Department of Chemistry , KU Leuven , Celestijnenlaan 200F , B-3001 Leuven , Belgium.,Institute of Transformative Bio-Molecules (WPI-ITbM) , Nagoya University , Chikusa , Nagoya 464-8602 , Japan
| | - Leonardo Belpassi
- Consortium for Computational Molecular and Materials Sciences (CMS)2 , via Elce di Sotto 8 , 06123 Perugia , Italy
| | - Jeremy N Harvey
- Department of Chemistry , KU Leuven , Celestijnenlaan 200F , B-3001 Leuven , Belgium
| | - Paola Belanzoni
- Consortium for Computational Molecular and Materials Sciences (CMS)2 , via Elce di Sotto 8 , 06123 Perugia , Italy
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6
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Mote NR, Chikkali SH. Hydrogen-Bonding-Assisted Supramolecular Metal Catalysis. Chem Asian J 2018; 13:3623-3646. [DOI: 10.1002/asia.201801302] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 10/09/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Nilesh R. Mote
- Polymer Science and Engineering Division; CSIR-National Chemical Laboratory; Dr. Homi Bhabha Road Pune- 411008 India
- Academy of Scientific and Innovative Research (AcSIR); Anusandhan Bhawan, 2 Rafi Marg New Delhi- 110001 India
| | - Samir H. Chikkali
- Polymer Science and Engineering Division; CSIR-National Chemical Laboratory; Dr. Homi Bhabha Road Pune- 411008 India
- Academy of Scientific and Innovative Research (AcSIR); Anusandhan Bhawan, 2 Rafi Marg New Delhi- 110001 India
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7
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Zafar MN, Nazar MF, Sumrra SH, Gul-E-Saba, Yasmin A, Atif AH. Development of some important nitrogen donor ligands for transition metal homogeneous catalysis. RUSS J COORD CHEM+ 2016. [DOI: 10.1134/s1070328416040072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Sainna MA, Kumar S, Kumar D, Fornarini S, Crestoni ME, de Visser SP. A comprehensive test set of epoxidation rate constants for iron(iv)-oxo porphyrin cation radical complexes. Chem Sci 2014; 6:1516-1529. [PMID: 29560240 PMCID: PMC5811088 DOI: 10.1039/c4sc02717e] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 12/08/2014] [Indexed: 12/31/2022] Open
Abstract
Trends in oxygen atom transfer to Compound I of the P450 models with an extensive test set have been studied and show a preferred regioselectivity of epoxidation over hydroxylation in the gas-phase for the first time.
Cytochrome P450 enzymes are heme based monoxygenases that catalyse a range of oxygen atom transfer reactions with various substrates, including aliphatic and aromatic hydroxylation as well as epoxidation reactions. The active species is short-lived and difficult to trap and characterize experimentally, moreover, it reacts in a regioselective manner with substrates leading to aliphatic hydroxylation and epoxidation products, but the origin of this regioselectivity is poorly understood. We have synthesized a model complex and studied it with low-pressure Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry (MS). A novel approach was devised using the reaction of [FeIII(TPFPP)]+ (TPFPP = meso-tetrakis(pentafluorophenyl)porphinato dianion) with iodosylbenzene as a terminal oxidant which leads to the production of ions corresponding to [FeIV(O)(TPFPP+˙)]+. This species was isolated in the gas-phase and studied in its reactivity with a variety of olefins. Product patterns and rate constants under Ideal Gas conditions were determined by FT-ICR MS. All substrates react with [FeIV(O)(TPFPP+˙)]+ by a more or less efficient oxygen atom transfer process. In addition, substrates with low ionization energies react by a charge-transfer channel, which enabled us to determine the electron affinity of [FeIV(O)(TPFPP+˙)]+ for the first time. Interestingly, no hydrogen atom abstraction pathways are observed for the reaction of [FeIV(O)(TPFPP+˙)]+ with prototypical olefins such as propene, cyclohexene and cyclohexadiene and also no kinetic isotope effect in the reaction rate is found, which suggests that the competition between epoxidation and hydroxylation – in the gas-phase – is in favour of substrate epoxidation. This notion further implies that P450 enzymes will need to adapt their substrate binding pocket, in order to enable favourable aliphatic hydroxylation over double bond epoxidation pathways. The MS studies yield a large test-set of experimental reaction rates of iron(iv)–oxo porphyrin cation radical complexes, so far unprecedented in the gas-phase, providing a benchmark for calibration studies using computational techniques. Preliminary computational results presented here confirm the observed trends excellently and rationalize the reactivities within the framework of thermochemical considerations and valence bond schemes.
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Affiliation(s)
- Mala A Sainna
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science , The University of Manchester , 131 Princess Street , Manchester M1 7DN , UK .
| | - Suresh Kumar
- Department of Applied Physics , School for Physical Sciences , Babasaheb Bhimrao Ambedkar University , Vidya Vihar, Rai Bareilly Road , Lucknow 226 025 , India .
| | - Devesh Kumar
- Department of Applied Physics , School for Physical Sciences , Babasaheb Bhimrao Ambedkar University , Vidya Vihar, Rai Bareilly Road , Lucknow 226 025 , India .
| | - Simonetta Fornarini
- Dipartimento di Chimica e Tecnologie del Farmaco , Università di Roma "La Sapienza" , P.le A. Moro 5 , 00185 , Roma , Italy . ;
| | - Maria Elisa Crestoni
- Dipartimento di Chimica e Tecnologie del Farmaco , Università di Roma "La Sapienza" , P.le A. Moro 5 , 00185 , Roma , Italy . ;
| | - Sam P de Visser
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science , The University of Manchester , 131 Princess Street , Manchester M1 7DN , UK .
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9
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Zhai F, Jordan RF. Hydrogen Bonding Behavior of Amide-Functionalized α-Diimine Palladium Complexes. Organometallics 2014. [DOI: 10.1021/om500978n] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Feng Zhai
- Department of Chemistry, The University of Chicago, 5735 South
Ellis Avenue, Chicago, Illinois 60637, United States
| | - Richard F. Jordan
- Department of Chemistry, The University of Chicago, 5735 South
Ellis Avenue, Chicago, Illinois 60637, United States
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10
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Zhang C, Srivastava P, Ellis-Guardiola K, Lewis JC. Manganese terpyridine artificial metalloenzymes for benzylic oxygenation and olefin epoxidation. Tetrahedron 2014; 70:4245-4249. [PMID: 24904188 DOI: 10.1016/j.tet.2014.03.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
New catalysts for non-directed hydrocarbon functionalization have great potential in organic synthesis. We hypothesized that incorporating a Mn-terpyridine cofactor into a protein scaffold would lead to artificial metalloenzymes (ArMs) in which the selectivity of the Mn cofactor could be controlled by the protein scaffold. We designed and synthesized a maleimide-substituted Mn-terpyridine cofactor and demonstrated that this cofactor could be incorporated into two different scaffold proteins to generate the desired ArMs. The structure and reactivity of one of these ArMs was explored, and the broad oxygenation capability of the Mn-terpyridine catalyst was maintained, providing a robust platform for optimization of ArMs for selective hydrocarbon functionalization.
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Affiliation(s)
- Chen Zhang
- Department of Chemistry, University of Chicago, 5735 S. Ellis Ave., Chicago, IL 60637 (USA)
| | - Poonam Srivastava
- Department of Chemistry, University of Chicago, 5735 S. Ellis Ave., Chicago, IL 60637 (USA)
| | - Ken Ellis-Guardiola
- Department of Chemistry, University of Chicago, 5735 S. Ellis Ave., Chicago, IL 60637 (USA)
| | - Jared C Lewis
- Department of Chemistry, University of Chicago, 5735 S. Ellis Ave., Chicago, IL 60637 (USA)
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11
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Dydio P, Reek JNH. Supramolecular control of selectivity in transition-metal catalysis through substrate preorganization. Chem Sci 2014. [DOI: 10.1039/c3sc53505c] [Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The Perspective highlights possibilities to use supramolecular interactions between a substrate molecule and a (bifunctional) catalyst as a powerful tool to control the selectivity in transition-metal catalysis.
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Affiliation(s)
- Paweł Dydio
- Homogeneous, Supramolecular and Bio-Inspired Catalysis, van't Hoff Institute for Molecular Sciences
- University of Amsterdam
- 1098 XH Amsterdam, The Netherlands
| | - Joost N. H. Reek
- Homogeneous, Supramolecular and Bio-Inspired Catalysis, van't Hoff Institute for Molecular Sciences
- University of Amsterdam
- 1098 XH Amsterdam, The Netherlands
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12
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Raynal M, Ballester P, Vidal-Ferran A, van Leeuwen PWNM. Supramolecular catalysis. Part 1: non-covalent interactions as a tool for building and modifying homogeneous catalysts. Chem Soc Rev 2014; 43:1660-733. [DOI: 10.1039/c3cs60027k] [Citation(s) in RCA: 519] [Impact Index Per Article: 51.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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13
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14
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Dydio P, Detz RJ, Reek JNH. Precise supramolecular control of selectivity in the Rh-catalyzed hydroformylation of terminal and internal alkenes. J Am Chem Soc 2013; 135:10817-28. [PMID: 23802682 DOI: 10.1021/ja4046235] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In this study, we report a series of DIMPhos ligands L1-L3, bidentate phosphorus ligands equipped with an integral anion binding site (the DIM pocket). Coordination studies show that these ligands bind to a rhodium center in a bidentate fashion. Experiments under hydroformylation conditions confirm the formation of the mononuclear hydridobiscarbonyl rhodium complexes that are generally assumed to be active in hydroformylation. The metal complexes formed still strongly bind the anionic species in the binding site of the ligand, without affecting the metal coordination sphere. These bifunctional properties of DIMPhos are further demonstrated by the crystal structure of the rhodium complex with acetate anion bound in the binding site of the ligand. The catalytic studies demonstrate that substrate preorganization by binding in the DIM pocket of the ligand results in unprecedented selectivities in hydroformylation of terminal and internal alkenes functionalized with an anionic group. Remarkably, the selectivity controlling anionic group can be even 10 bonds away from the reactive double bond, demonstrating the potential of this supramolecular approach. Control experiments confirm the crucial role of the anion binding for the selectivity. DFT studies on the decisive intermediates reveal that the anion binding in the DIM pocket restricts the rotational freedom of the reactive double bound. As a consequence, the pathway to the undesired product is strongly hindered, whereas that for the desired product is lowered in energy. Detailed kinetic studies, together with the in situ spectroscopic measurements and isotope-labeling studies, support this mode of operation and reveal that these supramolecular systems follow enzymatic-type Michaelis-Menten kinetics, with competitive product inhibition.
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Affiliation(s)
- Paweł Dydio
- van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
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15
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Kumar D, Latifi R, Kumar S, Rybak-Akimova EV, Sainna MA, de Visser SP. Rationalization of the Barrier Height for p-Z-styrene Epoxidation by Iron(IV)-Oxo Porphyrin Cation Radicals with Variable Axial Ligands. Inorg Chem 2013; 52:7968-79. [DOI: 10.1021/ic4005104] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Devesh Kumar
- Department of Applied Physics, School of Physical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar,
Rae Bareilly Road, Lucknow 226-025, India
| | - Reza Latifi
- Manchester Institute of Biotechnology and School
of Chemical Engineering and Analytical Science, University of Manchester, 131 Princess Street, Manchester M1 7DN,
U.K
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United
States
| | - Suresh Kumar
- Department of Applied Physics, School of Physical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar,
Rae Bareilly Road, Lucknow 226-025, India
| | | | - Mala A. Sainna
- Manchester Institute of Biotechnology and School
of Chemical Engineering and Analytical Science, University of Manchester, 131 Princess Street, Manchester M1 7DN,
U.K
| | - Sam P. de Visser
- Manchester Institute of Biotechnology and School
of Chemical Engineering and Analytical Science, University of Manchester, 131 Princess Street, Manchester M1 7DN,
U.K
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17
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Fackler P, Huber SM, Bach T. Enantio- and Regioselective Epoxidation of Olefinic Double Bonds in Quinolones, Pyridones, and Amides Catalyzed by a Ruthenium Porphyrin Catalyst with a Hydrogen Bonding Site. J Am Chem Soc 2012; 134:12869-78. [DOI: 10.1021/ja305890c] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Philipp Fackler
- Lehrstuhl für Organische Chemie I and Catalysis
Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
| | - Stefan M. Huber
- Lehrstuhl für Organische Chemie I and Catalysis
Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
| | - Thorsten Bach
- Lehrstuhl für Organische Chemie I and Catalysis
Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
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18
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Blakemore JD, Hull JF, Crabtree RH, Brudvig GW. Aqueous speciation and electrochemical properties of a water-soluble manganese phthalocyanine complex. Dalton Trans 2012; 41:7681-8. [PMID: 22585306 DOI: 10.1039/c2dt30371j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The speciation behavior of a water-soluble manganese(III) tetrasulfonated phthalocyanine complex was investigated with UV-visible and electron paramagnetic resonance (EPR) spectroscopies, as well as cyclic voltammetry. Parallel-mode EPR (in dimethylformamide : pyridine solvent mix) reveals a six-line hyperfine signal, centered at a g-value of 8.8, for the manganese(III) monomer, characteristic of the d(4)S = 2 system. The color of an aqueous solution containing the complex is dependent upon the pH of the solution; the phthalocyanine complex can exist as a water-bound monomer, a hydroxide-bound monomer, or an oxo-bridged dimer. Addition of coordinating bases such as borate or pyridine changes the speciation behavior by coordinating the manganese center. From the UV-visible spectra, complete speciation diagrams are plotted by global analysis of the pH-dependent UV-visible spectra, and a complete set of pK(a) values is obtained by fitting the data to a standard pK(a) model. Electrochemical studies reveal a pH-independent quasi-reversible oxidation event for the monomeric species, which likely involves oxidation of the organic ligand to the radical cation species. Adsorption of the phthalocyanine complex on the carbon working electrode was sometimes observed. The pK(a) values and electrochemistry data are discussed in the context of the development of mononuclear water-oxidation catalysts.
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Affiliation(s)
- James D Blakemore
- Department of Chemistry, Yale University, PO Box 208107, New Haven, Connecticut 06520-8107, USA
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19
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Wang BY, Žujović T, Turner DA, Hadad CM, Badjić JD. Design, Preparation, and Study of Catalytic Gated Baskets. J Org Chem 2012; 77:2675-88. [DOI: 10.1021/jo202443j] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bao-Yu Wang
- Department of Chemistry,
The Ohio State University,
Columbus, Ohio 43210, United States
| | - Teodora Žujović
- Department of Chemistry,
The Ohio State University,
Columbus, Ohio 43210, United States
| | - Daniel A. Turner
- Department of Chemistry,
The Ohio State University,
Columbus, Ohio 43210, United States
| | - Christopher M. Hadad
- Department of Chemistry,
The Ohio State University,
Columbus, Ohio 43210, United States
| | - Jovica D. Badjić
- Department of Chemistry,
The Ohio State University,
Columbus, Ohio 43210, United States
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20
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Winter A, Newkome GR, Schubert US. Catalytic Applications of Terpyridines and their Transition Metal Complexes. ChemCatChem 2011. [DOI: 10.1002/cctc.201100118] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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21
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Brewster TP, Blakemore JD, Schley ND, Incarvito CD, Hazari N, Brudvig GW, Crabtree RH. An Iridium(IV) Species, [Cp*Ir(NHC)Cl]+, Related to a Water-Oxidation Catalyst. Organometallics 2011. [DOI: 10.1021/om101016s] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Timothy P. Brewster
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
| | - James D. Blakemore
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
| | - Nathan D. Schley
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
| | - Christopher D. Incarvito
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
| | - Nilay Hazari
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
| | - Gary W. Brudvig
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
| | - Robert H. Crabtree
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, United States
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22
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Latifi R, Tahsini L, Karamzadeh B, Safari N, Nam W, de Visser SP. Manganese substituted Compound I of cytochrome P450 biomimetics: a comparative reactivity study of Mn(V)-oxo versus Mn(IV)-oxo species. Arch Biochem Biophys 2011; 507:4-13. [PMID: 21216220 DOI: 10.1016/j.abb.2010.12.035] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 12/30/2010] [Accepted: 12/30/2010] [Indexed: 10/18/2022]
Abstract
Manganese-oxo porphyrins have been well studied as biomimetic models of cytochromes P450 and are known to be able to catalyze substrate hydroxylation reactions. Recent experimental studies [J.Y. Lee, Y.-M. Lee, H. Kotani, W. Nam, S. Fukuzumi, Chem. Commun. (2009) 704] showed that Mn(V)-oxo porphyrins react rapidly with 10-methyl-9,10-dihydroacridine (AcrH(2)) via a proton-coupled-electron-transfer followed by an electron transfer. In this work, we present a computational study on the reactivity patterns of Mn(V)-oxo and Mn(IV)-oxo with respect to AcrH(2). This study shows that although both oxidants are capable of hydroxylating AcrH(2), the Mn(V)-oxo species is the more active oxidant. We have generalized these observations with thermodynamic cycles that explain the reaction mechanisms and electron transfer processes. For the Mn(V)-oxo mechanism the reactions proceed with a fast spin state crossing from the ground state singlet to the triplet spin state prior to a hydrogen atom transfer followed by another electron transfer. The present results are fully consistent with previous studies on iron-oxo porphyrins and manganese-oxo porphyrins and shows that the interplay of low lying singlet and triplet spin state surfaces influences the reaction mechanisms and kinetics.
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Affiliation(s)
- Reza Latifi
- The Manchester Interdisciplinary Biocenter, School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, UK
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Ballester P, Vidal-Ferran A, van Leeuwen PW. Modern Strategies in Supramolecular Catalysis. ADVANCES IN CATALYSIS 2011. [DOI: 10.1016/b978-0-12-387772-7.00002-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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Fackler P, Berthold C, Voss F, Bach T. Hydrogen-Bond-Mediated Enantio- and Regioselectivity in a Ru-Catalyzed Epoxidation Reaction. J Am Chem Soc 2010; 132:15911-3. [DOI: 10.1021/ja107601k] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Philipp Fackler
- Lehrstuhl für Organische Chemie I and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Carola Berthold
- Lehrstuhl für Organische Chemie I and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Felix Voss
- Lehrstuhl für Organische Chemie I and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Thorsten Bach
- Lehrstuhl für Organische Chemie I and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
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Kumar D, Karamzadeh B, Sastry GN, de Visser SP. What factors influence the rate constant of substrate epoxidation by compound I of cytochrome P450 and analogous iron(IV)-oxo oxidants? J Am Chem Soc 2010; 132:7656-67. [PMID: 20481499 DOI: 10.1021/ja9106176] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cytochromes P450 are a versatile range of mono-oxygenase enzymes that catalyze a variety of different chemical reactions, of which the key reactions include aliphatic hydroxylation and C=C double bond epoxidation. To establish the fundamental factors that govern substrate epoxidation by these enzymes we have done a systematic density functional theory study on substrate epoxidation by the active species of P450 enzymes, namely the iron(IV)-oxo porphyrin cation radical oxidant or Compound I. We show here, for the first time, that the rate constant of substrate epoxidation, and hence the activation energy, correlates with the ionization potential of the substrate as well as with intrinsic electronic properties of the active oxidant such as the polarizability volume. To explain these findings we present an electron-transfer model for the reaction mechanism that explains the factors that determine the barrier heights and developed a valence bond (VB) curve crossing mechanism to rationalize the observed trends. In addition, we have found a correlation for substrate epoxidation reactions catalyzed by a range of heme and nonheme iron(IV)-oxo oxidants with the strength of the O-H bond in the iron-hydroxo complex, i.e. BDE(OH), which is supported by the VB model. Finally, the fundamental factors that determine the regioselectivity change between substrate hydroxylation and epoxidation are discussed. It is shown that the regioselectivity of aliphatic hydroxylation versus double bond epoxidation is not influenced by the choice of the oxidant but is purely substrate dependent.
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Affiliation(s)
- Devesh Kumar
- Molecular Modelling Group, Indian Institute of Chemical Technology, Hyderabad 500-607, India.
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Hull JF, Balcells D, Sauer ELO, Raynaud C, Brudvig GW, Crabtree RH, Eisenstein O. Manganese catalysts for C-H activation: an experimental/theoretical study identifies the stereoelectronic factor that controls the switch between hydroxylation and desaturation pathways. J Am Chem Soc 2010; 132:7605-16. [PMID: 20481432 DOI: 10.1021/ja908744w] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe competitive C-H bond activation chemistry of two types, desaturation and hydroxylation, using synthetic manganese catalysts with several substrates. 9,10-Dihydrophenanthrene (DHP) gives the highest desaturation activity, the final products being phenanthrene (P1) and phenanthrene 9,10-oxide (P3), the latter being thought to arise from epoxidation of some of the phenanthrene. The hydroxylase pathway also occurs as suggested by the presence of the dione product, phenanthrene-9,10-dione (P2), thought to arise from further oxidation of hydroxylation intermediate 9-hydroxy-9,10-dihydrophenanthrene. The experimental work together with the density functional theory (DFT) calculations shows that the postulated Mn oxo active species, [Mn(O)(tpp)(Cl)] (tpp = tetraphenylporphyrin), can promote the oxidation of dihydrophenanthrene by either desaturation or hydroxylation pathways. The calculations show that these two competing reactions have a common initial step, radical H abstraction from one of the DHP sp(3) C-H bonds. The resulting Mn hydroxo intermediate is capable of promoting not only OH rebound (hydroxylation) but also a second H abstraction adjacent to the first (desaturation). Like the active Mn(V)=O species, this Mn(IV)-OH species also has radical character on oxygen and can thus give H abstraction. Both steps have very low and therefore very similar energy barriers, leading to a product mixture. Since the radical character of the catalyst is located on the oxygen p orbital perpendicular to the Mn(IV)-OH plane, the orientation of the organic radical with respect to this plane determines which reaction, desaturation or hydroxylation, will occur. Stereoelectronic factors such as the rotational orientation of the OH group in the enzyme active site are thus likely to constitute the switch between hydroxylase and desaturase behavior.
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Affiliation(s)
- Jonathan F Hull
- Chemistry Department, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, USA
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Reid SD, Wilson C, Blake AJ, Love JB. Tautomerisation and hydrogen-bonding interactions in four-coordinate metal halide and azide complexes of N-donor-extended dipyrromethanes. Dalton Trans 2010:418-25. [DOI: 10.1039/b909842a] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Fujita K, Akita M, Hikichi S. Acetoxybis(imidazolyl)methylborate [B(ImN-Me)2(OC(O)Me)Me]−: Carboxylation of borane moiety of imidazolyl-based scorpionate. Inorganica Chim Acta 2009. [DOI: 10.1016/j.ica.2009.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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