151
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Najafpour MM, Heidari S, Balaghi SE, Hołyńska M, Sadr MH, Soltani B, Khatamian M, Larkum AW, Allakhverdiev SI. Proposed mechanisms for water oxidation by Photosystem II and nanosized manganese oxides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:156-174. [DOI: 10.1016/j.bbabio.2016.11.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 11/05/2016] [Accepted: 11/08/2016] [Indexed: 12/18/2022]
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152
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Koepf M, Bergkamp JJ, Teillout AL, Llansola-Portoles MJ, Kodis G, Moore AL, Gust D, Moore TA. Design of porphyrin-based ligands for the assembly of [d-block metal : calcium] bimetallic centers. Dalton Trans 2017; 46:4199-4208. [DOI: 10.1039/c6dt04647a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A secondary binding-site for alkaline-earth cations is introduced on a porphyrin platform to obtain competent bitopicN,O-ligands.
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Affiliation(s)
- Matthieu Koepf
- School of Molecular Sciences
- Arizona State University
- Tempe
- USA
| | | | | | | | - Gerdenis Kodis
- School of Molecular Sciences
- Arizona State University
- Tempe
- USA
| | - Ana L. Moore
- School of Molecular Sciences
- Arizona State University
- Tempe
- USA
| | - Devens Gust
- School of Molecular Sciences
- Arizona State University
- Tempe
- USA
| | - Thomas A. Moore
- School of Molecular Sciences
- Arizona State University
- Tempe
- USA
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153
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Bansal D, Gupta R. Hydroxide-bridged dicopper complexes: the influence of secondary coordination sphere on structure and catecholase activity. Dalton Trans 2017; 46:4617-4627. [DOI: 10.1039/c6dt04858g] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This work illustrates the syntheses, structures and catecholase activities of dicopper(ii) complexes having a Cu(μ-OH)Cu core encased within a secondary coordination sphere intricately created by appended heterocyclic rings.
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Affiliation(s)
- Deepak Bansal
- Department of Chemistry
- University of Delhi
- Delhi 110 007
- India
| | - Rajeev Gupta
- Department of Chemistry
- University of Delhi
- Delhi 110 007
- India
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154
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Reiner BR, Foxman BM, Wade CR. Electrochemical and structural investigation of the interactions between naphthalene diimides and metal cations. Dalton Trans 2017; 46:9472-9480. [DOI: 10.1039/c7dt02067h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cyclic voltammetry and X-ray diffraction studies reveal the strength and nature of the interactions between Li+/Mg2+ and reduced naphthalene diimides.
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Affiliation(s)
| | | | - Casey R. Wade
- Department of Chemistry
- Brandeis University
- Waltham
- USA
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155
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Li J, Güttinger R, Moré R, Song F, Wan W, Patzke GR. Frontiers of water oxidation: the quest for true catalysts. Chem Soc Rev 2017; 46:6124-6147. [DOI: 10.1039/c7cs00306d] [Citation(s) in RCA: 178] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Development of advanced analytical techniques is essential for the identification of water oxidation catalysts together with mechanistic studies.
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Affiliation(s)
- J. Li
- University of Zurich
- Department of Chemistry
- CH-8057 Zurich
- Switzerland
| | - R. Güttinger
- University of Zurich
- Department of Chemistry
- CH-8057 Zurich
- Switzerland
| | - R. Moré
- University of Zurich
- Department of Chemistry
- CH-8057 Zurich
- Switzerland
| | - F. Song
- University of Zurich
- Department of Chemistry
- CH-8057 Zurich
- Switzerland
| | - W. Wan
- University of Zurich
- Department of Chemistry
- CH-8057 Zurich
- Switzerland
| | - G. R. Patzke
- University of Zurich
- Department of Chemistry
- CH-8057 Zurich
- Switzerland
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156
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Minato T, Suzuki K, Ohata Y, Yamaguchi K, Mizuno N. A modular synthesis approach to multinuclear heterometallic oxo clusters in polyoxometalates. Chem Commun (Camb) 2017. [DOI: 10.1039/c7cc04072e] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A “modular synthesis approach” to multinuclear heterometallic oxo clusters in lacunary polyoxometalates was successfully developed.
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Affiliation(s)
- Takuo Minato
- Department of Applied Chemistry
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
| | - Kosuke Suzuki
- Department of Applied Chemistry
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
| | - Yusuke Ohata
- Department of Applied Chemistry
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
| | - Kazuya Yamaguchi
- Department of Applied Chemistry
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
| | - Noritaka Mizuno
- Department of Applied Chemistry
- School of Engineering
- The University of Tokyo
- Tokyo 113-8656
- Japan
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157
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Bae SH, Lee Y, Fukuzumi S, Nam W. Fine Control of the Redox Reactivity of a Nonheme Iron(III)–Peroxo Complex by Binding Redox‐Inactive Metal Ions. Angew Chem Int Ed Engl 2016; 56:801-805. [DOI: 10.1002/anie.201610828] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Seong Hee Bae
- 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
| | - 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
| | - 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
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158
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Bae SH, Lee Y, Fukuzumi S, Nam W. Fine Control of the Redox Reactivity of a Nonheme Iron(III)–Peroxo Complex by Binding Redox‐Inactive Metal Ions. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201610828] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Seong Hee Bae
- 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
| | - 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
| | - 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
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159
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Svengren H, Jansson K, Grins J, Wan W, Torapava N, Johnsson M. Direct Synthesis of Two Inorganic Catalysts on Carbon Fibres for the Electrocatalytic Oxidation of Water. Chemistry 2016; 23:568-575. [PMID: 27862443 DOI: 10.1002/chem.201603085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Indexed: 11/07/2022]
Abstract
Two electrodes for anodic water oxidation made by direct synthesis of inorganic catalysts onto conductive carbon fibre sheets are evaluated. As catalysts two Co- and Sb-containing phases were tested, that is, Co3 Sb4 O6 F6 and the new compound CoSbO4 . The compounds express large differences in their morphology: CoSbO4 grows as thin needles whereas Co3 Sb4 O6 F6 grows as larger facetted crystals. Despite the smaller surface area the latter compound shows a better catalytic performance. When the compound Co3 Sb4 O6 F6 was used it gave a low increase of +0.028 mV h-1 at an overpotential of η=472 mV after 10 h and a stability of +0.48 mV h-1 at an overpotential of η=488 mV after 60 h. The leakages of Co and Sb were negligible and only <0.001 at % Co and approximately 0.02 at % Sb were detected in the electrolyte.
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Affiliation(s)
- Henrik Svengren
- Department of Materials and Environmental Chemistry, Stockholm University, 106 91, Stockholm, Sweden
| | - Kjell Jansson
- Department of Materials and Environmental Chemistry, Stockholm University, 106 91, Stockholm, Sweden
| | - Jekabs Grins
- Department of Materials and Environmental Chemistry, Stockholm University, 106 91, Stockholm, Sweden
| | - Wei Wan
- Department of Materials and Environmental Chemistry, Stockholm University, 106 91, Stockholm, Sweden
| | - Natallia Torapava
- MAX IV Laboratory, Lund University, 221 00, Lund, Sweden.,ALS Scandinavia AB, Aurorum 10, 977 75, Luleå, Sweden
| | - Mats Johnsson
- Department of Materials and Environmental Chemistry, Stockholm University, 106 91, Stockholm, Sweden
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160
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Kondo M, Masaoka S. Water Oxidation Catalysts Constructed by Biorelevant First-row Metal Complexes. CHEM LETT 2016. [DOI: 10.1246/cl.160639] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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161
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Abstract
Water oxidation is a key chemical transformation for the conversion of solar energy into chemical fuels. Our review focuses on recent work on robust earth-abundant heterogeneous catalysts for the oxygen-evolving reaction (OER). We point out that improvements in the performance of OER catalysts will depend critically on the success of work aimed at understanding reaction barriers based on atomic-level mechanisms. We highlight the challenge of obtaining acid-stable OER catalysts, with proposals for elements that could be employed to reach this goal. We suggest that future advances in solar fuels science will be accelerated by the development of new methods for materials synthesis and characterization, along with in-depth investigations of redox mechanisms at catalytic surfaces.
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Affiliation(s)
- Bryan M Hunter
- Beckman Institute and Division of Chemistry and Chemical Engineering, California Institute of Technology , M/C 139-74, Pasadena, California 91125, United States
| | - Harry B Gray
- Beckman Institute and Division of Chemistry and Chemical Engineering, California Institute of Technology , M/C 139-74, Pasadena, California 91125, United States
| | - Astrid M Müller
- Beckman Institute and Division of Chemistry and Chemical Engineering, California Institute of Technology , M/C 139-74, Pasadena, California 91125, United States
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162
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Fagiolari L, Scafuri A, Costantino F, Vivani R, Nocchetti M, Macchioni A. A Ternary Zn−Al−Ir Hydrotalcite-Like Compound Exhibiting High Efficiency and Recyclability as a Water Oxidation Catalyst. Chempluschem 2016; 81:1060-1063. [DOI: 10.1002/cplu.201600087] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 04/27/2016] [Indexed: 11/12/2022]
Affiliation(s)
- Lucia Fagiolari
- Department of Chemistry, Biology and Biotechnology and CIRCC; University of Perugia; Via Elce di Sotto 8 06123 Perugia Italy
| | - Antonio Scafuri
- Department of Pharmaceutical Sciences and CEMIN; University of Perugia; Via Fabretti 48 06123 Perugia Italy
| | - Ferdinando Costantino
- Department of Chemistry, Biology and Biotechnology and CIRCC; University of Perugia; Via Elce di Sotto 8 06123 Perugia Italy
| | - Riccardo Vivani
- Department of Pharmaceutical Sciences and CEMIN; University of Perugia; Via Fabretti 48 06123 Perugia Italy
| | - Morena Nocchetti
- Department of Pharmaceutical Sciences and CEMIN; University of Perugia; Via Fabretti 48 06123 Perugia Italy
| | - Alceo Macchioni
- Department of Chemistry, Biology and Biotechnology and CIRCC; University of Perugia; Via Elce di Sotto 8 06123 Perugia Italy
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163
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Baglia RA, Krest CM, Yang T, Leeladee P, Goldberg DP. High-Valent Manganese-Oxo Valence Tautomers and the Influence of Lewis/Brönsted Acids on C-H Bond Cleavage. Inorg Chem 2016; 55:10800-10809. [PMID: 27689821 DOI: 10.1021/acs.inorgchem.6b02109] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The addition of Lewis or Brönsted acids (LA = Zn(OTf)2, B(C6F5)3, HBArF, TFA) to the high-valent manganese-oxo complex MnV(O)(TBP8Cz) results in the stabilization of a valence tautomer MnIV(O-LA)(TBP8Cz•+). The ZnII and B(C6F5)3 complexes were characterized by manganese K-edge X-ray absorption spectroscopy (XAS). The position of the edge energies and the intensities of the pre-edge (1s to 3d) peaks confirm that the Mn ion is in the +4 oxidation state. Fitting of the extended X-ray absorption fine structure (EXAFS) region reveals 4 N/O ligands at Mn-Nave = 1.89 Å and a fifth N/O ligand at 1.61 Å, corresponding to the terminal oxo ligand. This Mn-O bond length is elongated compared to the MnV(O) starting material (Mn-O = 1.55 Å). The reactivity of MnIV(O-LA)(TBP8Cz•+) toward C-H substrates was examined, and it was found that H• abstraction from C-H bonds occurs in a 1:1 stoichiometry, giving a MnIV complex and the dehydrogenated organic product. The rates of C-H cleavage are accelerated for the MnIV(O-LA)(TBP8Cz•+) valence tautomer as compared to the MnV(O) valence tautomer when LA = ZnII, B(C6F5)3, and HBArF, whereas for LA = TFA, the C-H cleavage rate is slightly slower than when compared to MnV(O). A large, nonclassical kinetic isotope effect of kH/kD = 25-27 was observed for LA = B(C6F5)3 and HBArF, indicating that H-atom transfer (HAT) is the rate-limiting step in the C-H cleavage reaction and implicating a potential tunneling mechanism for HAT. The reactivity of MnIV(O-LA)(TBP8Cz•+) toward C-H bonds depends on the strength of the Lewis acid. The HAT reactivity is compared with the analogous corrole complex MnIV(O-H)(tpfc•+) recently reported (J. Am. Chem. Soc. 2015, 137, 14481-14487).
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Affiliation(s)
- Regina A Baglia
- Department of Chemistry, The Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Courtney M Krest
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Tzuhsiung Yang
- Department of Chemistry, The Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Pannee Leeladee
- Department of Chemistry, The Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
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164
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Hadt RG, Hayes D, Brodsky CN, Ullman AM, Casa DM, Upton MH, Nocera DG, Chen LX. X-ray Spectroscopic Characterization of Co(IV) and Metal-Metal Interactions in Co4O4: Electronic Structure Contributions to the Formation of High-Valent States Relevant to the Oxygen Evolution Reaction. J Am Chem Soc 2016; 138:11017-30. [PMID: 27515121 DOI: 10.1021/jacs.6b04663] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The formation of high-valent states is a key factor in making highly active transition-metal-based catalysts of the oxygen evolution reaction (OER). These high oxidation states will be strongly influenced by the local geometric and electronic structures of the metal ion, which are difficult to study due to spectroscopically active and complex backgrounds, short lifetimes, and limited concentrations. Here, we use a wide range of complementary X-ray spectroscopies coupled to DFT calculations to study Co(III)4O4 cubanes and their first oxidized derivatives, which provide insight into the high-valent Co(IV) centers responsible for the activity of molecular and heterogeneous OER catalysts. The combination of X-ray absorption and 1s3p resonant inelastic X-ray scattering (Kβ RIXS) allows Co(IV) to be isolated and studied against a spectroscopically active Co(III) background. Co K- and L-edge X-ray absorption data allow for a detailed characterization of the 3d-manifold of effectively localized Co(IV) centers and provide a direct handle on the t2g-based redox-active molecular orbital. Kβ RIXS is also shown to provide a powerful probe of Co(IV), and specific spectral features are sensitive to the degree of oxo-mediated metal-metal coupling across Co4O4. Guided by the data, calculations show that electron-hole delocalization can actually oppose Co(IV) formation. Computational extension of Co4O4 to CoM3O4 structures (M = redox-inactive metal) defines electronic structure contributions to Co(IV) formation. Redox activity is shown to be linearly related to covalency, and M(III) oxo inductive effects on Co(IV) oxo bonding can tune the covalency of high-valent sites over a large range and thereby tune E(0) over hundreds of millivolts. Additionally, redox-inactive metal substitution can also switch the ground state and modify metal-metal and antibonding interactions across the cluster.
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Affiliation(s)
| | | | - Casey N Brodsky
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Andrew M Ullman
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | | | | | - Daniel G Nocera
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
| | - Lin X Chen
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
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165
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Gerey B, Gouré E, Fortage J, Pécaut J, Collomb MN. Manganese-calcium/strontium heterometallic compounds and their relevance for the oxygen-evolving center of photosystem II. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2016.04.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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166
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Perlepe PS, Cunha-Silva L, Bekiari V, Gagnon KJ, Teat SJ, Escuer A, Stamatatos TC. Structural diversity in Ni(II) cluster chemistry: Ni5, Ni6, and {NiNa2}n complexes bearing the Schiff-base ligand N-naphthalidene-2-amino-5-chlorobenzoic acid. Dalton Trans 2016; 45:10256-70. [PMID: 27240998 DOI: 10.1039/c6dt01162d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The employment of the fluorescent bridging and chelating ligand N-naphthalidene-2-amino-5-chlorobenzoic acid (nacbH2) in Ni(II) cluster chemistry has led to a series of pentanuclear and hexanuclear compounds with different structural motifs, magnetic and optical properties, as well as an interesting 1-D coordination polymer. Synthetic parameters such as the inorganic anion present in the NiX2 starting materials (X = ClO4(-) or Cl(-)), the reaction solvent and the nature of the organic base employed for the deprotonation of nacbH2 were proved to be structure-directing components. Undoubtedly, the reported results demonstrate the rich coordination chemistry of nacbH2 in the presence of Ni(II) metal ions and the ability of this chelate to adopt a variety of different modes, thus fostering the formation of high-nuclearity molecules with many physical properties.
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Affiliation(s)
- Panagiota S Perlepe
- Department of Chemistry, Brock University, St. Catharines, Ontario L2S 3A1, Canada.
| | - Luís Cunha-Silva
- REQUIMTE/LAQV & Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - Vlasoula Bekiari
- Department of Aquaculture and Fisheries Management, Technological Educational Institute of Western Greece, 30 200 Messolonghi, Greece
| | - Kevin J Gagnon
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Simon J Teat
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Albert Escuer
- Departament de Quimica Inorganica and Institut de Nanociencia i Nanotecnologia (IN2UB), Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
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167
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Najafpour MM, Ghobadi MZ, Sarvi B, Haghighi B. An engineered polypeptide around nano-sized manganese-calcium oxide: copying plants for water oxidation. Dalton Trans 2016; 44:15271-8. [PMID: 26017548 DOI: 10.1039/c5dt01443c] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Synthesis of new efficient catalysts inspired by Nature is a key goal in the production of clean fuel. Different compounds based on manganese oxide have been investigated in order to find their water-oxidation activity. Herein, we introduce a novel engineered polypeptide containing tyrosine around nano-sized manganese-calcium oxide, which was shown to be a highly active catalyst toward water oxidation at low overpotential (240 mV), with high turnover frequency of 1.5 × 10(-2) s(-1) at pH = 6.3 in the Mn(III)/Mn(IV) oxidation range. The compound is a novel structural and efficient functional model for the water-oxidizing complex in Photosystem II. A new proposed clever strategy used by Nature in water oxidation is also discussed. The new model of the water-oxidizing complex opens a new perspective for synthesis of efficient water-oxidation catalysts.
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Affiliation(s)
- Mohammad Mahdi Najafpour
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, 45137-66731, Iran.
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168
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Chan KW, Ng WM, Cheung WM, Lai CS, Sung HH, Williams ID, Leung WH. Di- and tri-nuclear ruthenium nitrosyl complexes containing thiolate ligands. J Organomet Chem 2016. [DOI: 10.1016/j.jorganchem.2016.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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169
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Preparation, structures and properties of manganese complexes containing amine–(amido or amidato)–phenolato type ligands. Inorganica Chim Acta 2016. [DOI: 10.1016/j.ica.2016.03.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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170
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Jung J, Neu HM, Leeladee P, Siegler MA, Ohkubo K, Goldberg DP, Fukuzumi S. Photocatalytic Oxygenation of Substrates by Dioxygen with Protonated Manganese(III) Corrolazine. Inorg Chem 2016; 55:3218-28. [PMID: 26974004 PMCID: PMC4893963 DOI: 10.1021/acs.inorgchem.5b02019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
UV-vis spectral titrations of a manganese(III) corrolazine complex [Mn(III)(TBP8Cz)] with HOTf in benzonitrile (PhCN) indicate mono- and diprotonation of Mn(III)(TBP8Cz) to give Mn(III)(OTf)(TBP8Cz(H)) and [Mn(III)(OTf)(H2O)(TBP8Cz(H)2)][OTf] with protonation constants of 9.0 × 10(6) and 4.7 × 10(3) M(-1), respectively. The protonated sites of Mn(III)(OTf)(TBP8Cz(H)) and [Mn(III)(OTf)(H2O)(TBP8Cz(H)2)][OTf] were identified by X-ray crystal structures of the mono- and diprotonated complexes. In the presence of HOTf, the monoprotonated manganese(III) corrolazine complex [Mn(III)(OTf)(TBP8Cz(H))] acts as an efficient photocatalytic catalyst for the oxidation of hexamethylbenzene and thioanisole by O2 to the corresponding alcohol and sulfoxide with 563 and 902 TON, respectively. Femtosecond laser flash photolysis measurements of Mn(III)(OTf)(TBP8Cz(H)) and [Mn(III)(OTf)(H2O)(TBP8Cz(H)2)][OTf] in the presence of O2 revealed the formation of a tripquintet excited state, which was rapidly converted to a tripseptet excited state. The tripseptet excited state of Mn(III)(OTf)(TBP8Cz(H)) reacted with O2 with a diffusion-limited rate constant to produce the putative Mn(IV)(O2(•-))(OTf)(TBP8Cz(H)), whereas the tripseptet excited state of [Mn(III)(OTf)(H2O)(TBP8Cz(H)2)][OTf] exhibited no reactivity toward O2. In the presence of HOTf, Mn(V)(O)(TBP8Cz) can oxidize not only HMB but also mesitylene to the corresponding alcohols, accompanied by regeneration of Mn(III)(OTf)(TBP8Cz(H)). This thermal reaction was examined for a kinetic isotope effect, and essentially no KIE (1.1) was observed for the oxidation of mesitylene-d12, suggesting a proton-coupled electron transfer (PCET) mechanism is operative in this case. Thus, the monoprotonated manganese(III) corrolazine complex, Mn(III)(OTf)(TBP8Cz(H)), acts as an efficient photocatalyst for the oxidation of HMB by O2 to the alcohol.
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Affiliation(s)
- Jieun Jung
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Heather M. Neu
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Pannee Leeladee
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Maxime A. Siegler
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Kei Ohkubo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
- 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
| | - David P. Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
- 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
- Faculty of Science and Engineering, Meijo University, ALCA and SEN TAN, Japan Science and Technology Agency (JST), Nagoya, Aichi 468-0073, Japan
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171
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Cui P, Hoffbauer MR, Vyushkova M, Iluc VM. Heterobimetallic Pd-K carbene complexes via one-electron reductions of palladium radical carbenes. Chem Sci 2016; 7:4444-4452. [PMID: 30155092 PMCID: PMC6014298 DOI: 10.1039/c6sc00948d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 03/21/2016] [Indexed: 12/24/2022] Open
Abstract
Heterobimetallic Pd-K carbenes featuring Pd-Ccarbene-K moieties were synthesized via an unprecedented sequential substitution/reduction reaction from a radical precursor, [{PC˙(sp2)P} tBuPdI] ([PC(sp2)P] tBu = bis[2-(di-iso-propylphosphino)-4-tert-butylphenyl]methylene). Polymeric structures were observed in the solid state for the heterobimetallic compounds that can be interrupted in the presence of a donor solvent.
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Affiliation(s)
- Peng Cui
- Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN 46556 , USA .
| | - Melissa R Hoffbauer
- Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN 46556 , USA .
| | - Mariya Vyushkova
- Notre Dame Radiation Laboratory , University of Notre Dame , Notre Dame , IN 46556 , USA
| | - Vlad M Iluc
- Department of Chemistry and Biochemistry , University of Notre Dame , Notre Dame , IN 46556 , USA .
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172
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Lovyagina ER, Semin BK. Mechanism of inhibition and decoupling of oxygen evolution from electron transfer in photosystem II by fluoride, ammonia and acetate. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2016; 158:145-53. [PMID: 26971280 DOI: 10.1016/j.jphotobiol.2016.02.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 02/08/2016] [Accepted: 02/11/2016] [Indexed: 11/25/2022]
Abstract
Ca(2+) extraction from oxygen-evolving complex (OEC) of photosystem II (PSII) is accompanied by decoupling of oxygen evolution/electron transfer processes [Semin et al. Photosynth. Res. 98 (2008) 235] and appearance of a broad EPR signal at g=2 (split "S3" signal) what can imply the relationship between these effects. Split signal have been observed not only in Ca-depleted PSII but also in PSII membranes treated by fluoride anions, sodium acetate, and NH4Cl. Here we investigated the question: can such compounds induce the decoupling effect during treatment of PSII like Ca(2+) extraction does? We found that F(-), sodium acetate, and NH4Cl inhibit O2 evolution in PSII membranes more effectively than the reduction of artificial electron acceptor 2,6-dichlorophenolindophenol, i.e. the action of these compounds is accompanied by decoupling of these processes in OEC. Similarity of effects observed after Ca(2+) extraction and F(-), CH3COO(-) or NH4Cl treatments suggests that these compounds can inactivate function of Ca(2+). Such inactivation could originate from disturbance of the network of functionally active hydrogen bonds around OEC formed with participation of Ca(2+). This inhibition effect is observed in the region of low concentration of inhibitors. Increasing of inhibitor concentration is accompanied by appearance of other sites of inhibition.
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Affiliation(s)
- E R Lovyagina
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - B K Semin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia.
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173
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González-Flores D, Zaharieva I, Heidkamp J, Chernev P, Martínez-Moreno E, Pasquini C, Mohammadi MR, Klingan K, Gernet U, Fischer A, Dau H. Electrosynthesis of Biomimetic Manganese-Calcium Oxides for Water Oxidation Catalysis--Atomic Structure and Functionality. CHEMSUSCHEM 2016; 9:379-387. [PMID: 26692571 DOI: 10.1002/cssc.201501399] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Indexed: 06/05/2023]
Abstract
Water-oxidizing calcium-manganese oxides, which mimic the inorganic core of the biological catalyst, were synthesized and structurally characterized by X-ray absorption spectroscopy at the manganese and calcium K edges. The amorphous, birnesite-type oxides are obtained through a simple protocol that involves electrodeposition followed by active-site creation through annealing at moderate temperatures. Calcium ions are inessential, but tune the electrocatalytic properties. For increasing calcium/manganese molar ratios, both Tafel slopes and exchange current densities decrease gradually, resulting in optimal catalytic performance at calcium/manganese molar ratios of close to 10 %. Tracking UV/Vis absorption changes during electrochemical operation suggests that inactive oxides reach their highest, all-Mn(IV) oxidation state at comparably low electrode potentials. The ability to undergo redox transitions and the presence of a minor fraction of Mn(III) ions at catalytic potentials is identified as a prerequisite for catalytic activity.
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Affiliation(s)
- Diego González-Flores
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Ivelina Zaharieva
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Jonathan Heidkamp
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Petko Chernev
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Elías Martínez-Moreno
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Chiara Pasquini
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | | | - Katharina Klingan
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Ulrich Gernet
- Technical University Berlin, Department of Chemistry, Straße des 17. Juni 135, 10623, Berlin, Germany
- Institute of Inorganic and Analytical Chemistry, Albert-Ludwigs-University Freiburg, Albertstrasse 21, 76104, Freiburg, Germany
| | - Anna Fischer
- Technical University Berlin, Department of Chemistry, Straße des 17. Juni 135, 10623, Berlin, Germany
- Institute of Inorganic and Analytical Chemistry, Albert-Ludwigs-University Freiburg, Albertstrasse 21, 76104, Freiburg, Germany
| | - Holger Dau
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
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174
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Hodel FH, Luber S. What Influences the Water Oxidation Activity of a Bioinspired Molecular CoII4O4 Cubane? An In-Depth Exploration of Catalytic Pathways. ACS Catal 2016. [DOI: 10.1021/acscatal.5b02507] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Florian H. Hodel
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Sandra Luber
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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175
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Mognon L, Mandal S, Castillo CE, Fortage J, Molton F, Aromí G, Benet-Buchhlolz J, Collomb MN, Llobet A. Synthesis, structure, spectroscopy and reactivity of new heterotrinuclear water oxidation catalysts. Chem Sci 2016; 7:3304-3312. [PMID: 29997822 PMCID: PMC6006862 DOI: 10.1039/c5sc04672f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/01/2016] [Indexed: 11/21/2022] Open
Abstract
Four heterotrinuclear complexes containing the ligands 3,5-bis(2-pyridyl)pyrazolate (bpp-) and 2,2':6',2''-terpyridine (trpy) of the general formula {[RuII(trpy)]2(μ-[M(X)2(bpp)2])}(PF6)2, where M = CoII, MnII and X = Cl-, AcO- (M = CoII, X = Cl-: Ru2Co-Cl2 ; M = MnII, X = Cl-: Ru2Mn-Cl2 ; M = CoII, X = AcO-: Ru2Co-OAc2 ; M = MnII, X = AcO-: Ru2Mn-OAc2 ), have been prepared for the first time. The complexes have been characterized using different spectroscopic techniques such as UV-vis, IR, and mass spectrometry. X-Ray diffraction analyses have been used to characterize the Ru2Mn-Cl2 and Ru2Mn-OAc2 complexes. The cyclic voltammograms (CV) for all four complexes in organic solvent (CH3CN or CH2Cl2) display three successive reversible oxidative waves corresponding to one-electron oxidations of each of the three metal centers. The oxidized forms of the complexes Ru2Co-OAc2 and Ru2Mn-OAc2 are further characterized by EPR and UV-vis spectroscopy. The magnetic susceptibility measurements of all complexes in the temperature range of 2-300 K reveal paramagnetic properties due to the presence of high spin Co(ii) and Mn(ii) centers. The complexes Ru2Co-OAc2 and Ru2Mn-OAc2 act as precatalysts for the water oxidation reaction, since the acetato groups are easily replaced by water at pH = 7 generating the active catalysts, {[Ru(H2O)(trpy)]2(μ-[M(H2O)2(bpp)2])}4+ (M = CoII: Ru2Co-(H2O)4 ; M = MnII: Ru2Mn-(H2O)4 ). The photochemical water oxidation reaction is studied using [Ru(bpy)3]2+ as the photosensitizer and Na2S2O8 as a sacrificial electron acceptor at pH = 7. The Co containing complex generates a TON of 50 in about 10 minutes (TOFi = 0.21 s-1), whereas the Mn containing complex only generates a TON of 8. The water oxidation reaction of Ru2Co-(H2O)4 is further investigated using oxone as a sacrificial chemical oxidant at pH = 7. Labelled water oxidation experiments suggest that a nucleophilic attack mechanism is occurring at the Co site of the trinuclear complex with cooperative involvement of the two Ru sites, via electronic coupling through the bpp- bridging ligand and via neighboring hydrogen bonding.
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Affiliation(s)
- Lorenzo Mognon
- Institute of Chemical Research of Catalonia (ICIQ) , Barcelona Institute of Science and Technology , Avinguda Països Catalans 16 , 43007 Tarragona , Spain .
| | - Sukanta Mandal
- Department of Chemistry , Indian Institute of Technology Kharagpur , Kharagpur-721302 , West Bengal , India
| | - Carmen E Castillo
- Univ. Grenoble Alpes , DCM , F-38000 Grenoble , France.,CNRS , DCM , F-38000 Grenoble , France
| | - Jérôme Fortage
- Univ. Grenoble Alpes , DCM , F-38000 Grenoble , France.,CNRS , DCM , F-38000 Grenoble , France
| | - Florian Molton
- Univ. Grenoble Alpes , DCM , F-38000 Grenoble , France.,CNRS , DCM , F-38000 Grenoble , France
| | - Guillem Aromí
- Departament de Química Inorgànica , Universitat de Barcelona , Diagonal 645 , 08028 Barcelona , Spain
| | - Jordi Benet-Buchhlolz
- Institute of Chemical Research of Catalonia (ICIQ) , Barcelona Institute of Science and Technology , Avinguda Països Catalans 16 , 43007 Tarragona , Spain .
| | - Marie-Noëlle Collomb
- Univ. Grenoble Alpes , DCM , F-38000 Grenoble , France.,CNRS , DCM , F-38000 Grenoble , France
| | - Antoni Llobet
- Institute of Chemical Research of Catalonia (ICIQ) , Barcelona Institute of Science and Technology , Avinguda Països Catalans 16 , 43007 Tarragona , Spain . .,Departament de Química , Universitat Autònoma de Barcelona , Cerdanyola del Vallès , 08193 Barcelona , Spain
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176
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Ma L, Lam WWY, Lo PK, Lau KC, Lau TC. Ca(2+) -Induced Oxygen Generation by FeO4(2-) at pH 9-10. Angew Chem Int Ed Engl 2016; 55:3012-6. [PMID: 26798981 DOI: 10.1002/anie.201510156] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Indexed: 11/07/2022]
Abstract
Although FeO4(2-) (ferrate(IV)) is a very strong oxidant that readily oxidizes water in acidic medium, at pH 9-10 it is relatively stable (<2 % decomposition after 1 h at 298 K). However, FeO4(2-) is readily activated by Ca(2+) at pH 9-10 to generate O2. The reaction has the following rate law: d[O2]/dt=kCa [Ca(2+) ][FeO4(2-)](2). (18)O-labeling experiments show that both O atoms in O2 come from FeO4(2-). These results together with DFT calculations suggest that the function of Ca(2+) is to facilitate O-O coupling between two FeO4 (2-) ions by bridging them together. Similar activating effects are also observed with Mg(2+) and Sr(2+).
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Affiliation(s)
- Li Ma
- Department of Biology and Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - William W Y Lam
- Department of Biology and Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Po-Kam Lo
- Department of Biology and Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Kai-Chung Lau
- Department of Biology and Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China.
| | - Tai-Chu Lau
- Department of Biology and Chemistry and Institute of Molecular Functional Materials, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China.
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177
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Ma L, Lam WWY, Lo PK, Lau KC, Lau TC. Ca2+
-Induced Oxygen Generation by FeO4
2−
at pH 9-
10. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201510156] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Li Ma
- Department of Biology and Chemistry and Institute of Molecular Functional Materials; City University of Hong Kong; Tat Chee Avenue, Kowloon Tong Hong Kong China
| | - William W. Y. Lam
- Department of Biology and Chemistry and Institute of Molecular Functional Materials; City University of Hong Kong; Tat Chee Avenue, Kowloon Tong Hong Kong China
| | - Po-Kam Lo
- Department of Biology and Chemistry and Institute of Molecular Functional Materials; City University of Hong Kong; Tat Chee Avenue, Kowloon Tong Hong Kong China
| | - Kai-Chung Lau
- Department of Biology and Chemistry and Institute of Molecular Functional Materials; City University of Hong Kong; Tat Chee Avenue, Kowloon Tong Hong Kong China
| | - Tai-Chu Lau
- Department of Biology and Chemistry and Institute of Molecular Functional Materials; City University of Hong Kong; Tat Chee Avenue, Kowloon Tong Hong Kong China
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178
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Influence of Lewis acid charge and proximity in Mo Mo⋯M linear chain compounds with M = Na+, Ca2+, Sr2+, and Y3+. Polyhedron 2016. [DOI: 10.1016/j.poly.2015.09.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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179
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Kärkäs MD, Åkermark B. Water oxidation using earth-abundant transition metal catalysts: opportunities and challenges. Dalton Trans 2016; 45:14421-61. [DOI: 10.1039/c6dt00809g] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Catalysts for the oxidation of water are a vital component of solar energy to fuel conversion technologies. This Perspective summarizes recent advances in the field of designing homogeneous water oxidation catalysts (WOCs) based on Mn, Fe, Co and Cu.
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Affiliation(s)
- Markus D. Kärkäs
- Department of Organic Chemistry
- Arrhenius Laboratory
- Stockholm University
- SE-106 91 Stockholm
- Sweden
| | - Björn Åkermark
- Department of Organic Chemistry
- Arrhenius Laboratory
- Stockholm University
- SE-106 91 Stockholm
- Sweden
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180
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Svengren H, Torapava N, Athanassiadis I, Ali SI, Johnsson M. A transition metal oxofluoride offering advantages in electrocatalysis and potential use in applications. Faraday Discuss 2016; 188:481-98. [DOI: 10.1039/c5fd00169b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The recently described solid solution (Co,Ni,Mn)3Sb4O6F6has proved stable and efficient as a catalyst for electrocatalytic water oxidation. The end component Co3Sb4O6F6was found to be most efficient, maintaining a current density ofj= 10 mA cm−2at an overpotential of 443 mV with good capability. At this current density, O2and H2were produced in the ratio 1 : 2 without loss of faradaic current against a Pt-cathode. A morphological change in the crystallite surface was observed after 0.5 h, however, even after 64.5 h, the overall shape and size of the small crystallites were unaffected and the electrolyte contained only 0.02 at% Co. It was also possible to conclude fromin situEXAFS measurements that the coordination around Co did not change. The oxofluorides express both hydrophilic and hydrophobic surface sites, incorporate a flexible metalloid element and offer the possibility of a mechanism that differs from other inorganic catalytic pathways previously described.
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Affiliation(s)
- H. Svengren
- Department of Materials and Environmental Chemistry
- Stockholm University
- SE-106 91 Stockholm
- Sweden
| | - N. Torapava
- Max IV Laboratory
- Lund University
- SE-221 00 Lund
- Sweden
| | - I. Athanassiadis
- Department of Materials and Environmental Chemistry
- Stockholm University
- SE-106 91 Stockholm
- Sweden
| | - S. I. Ali
- Department of Materials and Environmental Chemistry
- Stockholm University
- SE-106 91 Stockholm
- Sweden
| | - M. Johnsson
- Department of Materials and Environmental Chemistry
- Stockholm University
- SE-106 91 Stockholm
- Sweden
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181
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Wang J, Lin WF, Shi Y, Wang HS, Rong LQ, Xia XH. A simple way to fine tune the redox potentials of cobalt ions encapsulated in nitrogen doped graphene molecular catalysts for the oxygen evolution reaction. Chem Commun (Camb) 2016; 52:13409-13412. [DOI: 10.1039/c6cc08047b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A simple approach to fine-tuning the redox potential of Co2+ ions encapsulated in nitrogen doped graphene (NG) has been proposed. We found that the redox potential determines the oxygen evolution reaction activity of the catalyst.
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Affiliation(s)
- Jiong Wang
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
- China
| | - Wen-Feng Lin
- Department of Chemical Engineering
- Loughborough University
- UK
| | - Yi Shi
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
- China
| | - Huai-Song Wang
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
- China
| | - Lian-Qing Rong
- Department of Materials and Chemical Engineering
- Pingxiang University
- Pingxiang 337055
- China
| | - Xing-Hua Xia
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210093
- China
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182
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Krewald V, Neese F, Pantazis DA. Redox potential tuning by redox-inactive cations in nature's water oxidizing catalyst and synthetic analogues. Phys Chem Chem Phys 2016; 18:10739-50. [DOI: 10.1039/c5cp07213a] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Fundamental differences between synthetic manganese clusters and the biological water oxidizing catalyst are demonstrated in the modulation of their redox potential by redox-inactive cations.
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Affiliation(s)
- Vera Krewald
- Max Planck Institute for Chemical Energy Conversion
- 45470 Mülheim an der Ruhr
- Germany
| | - Frank Neese
- Max Planck Institute for Chemical Energy Conversion
- 45470 Mülheim an der Ruhr
- Germany
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183
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Giannopoulos DP, Cunha-Silva L, Ballesteros-Garrido R, Ballesteros R, Abarca B, Escuer A, Stamatatos TC. New structural motifs in Mn cluster chemistry from the ketone/gem-diol and bis(gem-diol) forms of 2,6-di-(2-pyridylcarbonyl)pyridine: {MnII4MnIII2} and {MnII4MnIII6} complexes. RSC Adv 2016. [DOI: 10.1039/c6ra22953k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The ketone/gem-diol (L1H2) and bis(gem-diol) (L2H4) forms of the ligand 2,6-di-(2-pyridylcarbonyl)pyridine in Mn cluster chemistry have afforded the new complexes [MnII4MnIII2(N3)6Cl4(L1)2(DMF)4] and [MnII4MnIII6O2(N3)12(L1)2(L2H)2(DMF)6].
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Affiliation(s)
| | - Luís Cunha-Silva
- REQUIMTE-LAQV
- Department of Chemistry and Biochemistry
- Faculty of Sciences
- University of Porto
- 4169-007 Porto
| | | | - Rafael Ballesteros
- Departamento de Química Orgánica
- Faculdad de Farmacia
- Universidad de Valencia
- 46100 Burjassot
- Spain
| | - Belén Abarca
- Departamento de Química Orgánica
- Faculdad de Farmacia
- Universidad de Valencia
- 46100 Burjassot
- Spain
| | - Albert Escuer
- Departament de Quimica Inorganica i Organica
- Seccio Inorgànica and Institut de Nanociencia i Nanotecnologia (IN2UB)
- Universitat de Barcelona
- 08028 Barcelona
- Spain
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184
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Wallen CM, Wielizcko M, Bacsa J, Scarborough CC. Heterotrimetallic sandwich complexes supported by sulfonamido ligands. Inorg Chem Front 2016. [DOI: 10.1039/c5qi00233h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
CoII complexes bearing sulfonamido ligands derived from tris(2-aminoethyl)amine (H6tren) assemble into complex architectures in the presence of Group II ions through interactions between the Group II ion and the sulfonyl oxygens.
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Affiliation(s)
| | | | - John Bacsa
- Department of Chemistry
- Emory University
- Atlanta
- USA
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185
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Tao S, Wang X, Cui P, Wang Y, Haleem YA, Wei S, Huang W, Song L, Chu W. Fabrication of graphene-encapsulated Na3V2(PO4)3 as high-performance cathode materials for sodium-ion batteries. RSC Adv 2016. [DOI: 10.1039/c6ra04237f] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A thin layers graphene-encapsulated Na3V2(PO4)3 (NVP/G) has been in the spotlight as a potential candidate of next generation batteries to compensate the intrinsic low electronic conductivity of NVP and strengthen its structure stable.
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Affiliation(s)
- Shi Tao
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- People's Republic of China
- Advanced Functional Materials Lab and Department of Physics
| | - Xingbo Wang
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- People's Republic of China
| | - Peixin Cui
- Key Laboratory of Soil Environment and Pollution Remediation
- Institute of Soil Science
- Chinese Academy of Sciences
- Nanjing 210008
- People's Republic of China
| | - Yu Wang
- Shanghai Synchrotron Radiation Facility
- Shanghai Institute of Applied Physics
- Chinese Academy of Sciences
- Shanghai 201204
- People's Republic of China
| | - Yasir A. Haleem
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- People's Republic of China
| | - Shenghui Wei
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- People's Republic of China
| | - Weifeng Huang
- Key Lab of Theory and Technology for Advanced Batteries Materials
- College of Engineering
- Peking University
- Beijing 100871
- People's Republic of China
| | - Li Song
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- People's Republic of China
| | - Wangsheng Chu
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- People's Republic of China
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186
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Delgado M, Ziegler JM, Seda T, Zakharov LN, Gilbertson JD. Pyridinediimine Iron Complexes with Pendant Redox-Inactive Metals Located in the Secondary Coordination Sphere. Inorg Chem 2015; 55:555-7. [PMID: 26692111 DOI: 10.1021/acs.inorgchem.5b02544] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of pyridinediimine (PDI) iron complexes that contain a pendant 15-crown-5 located in the secondary coordination sphere were synthesized and characterized. The complex Fe((15c5)PDI)(CO)2 (2) was shown in both the solid state and solution to encapsulate redox-inactive metal ions. Modest shifts in the reduction potential of the metal-ligand scaffold were observed upon encapsulation of either Na(+) or Li(+).
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Affiliation(s)
| | | | | | - Lev N Zakharov
- Department of Chemistry, University of Oregon , Eugene, Oregon 97403, United States
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187
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Escriche-Tur L, Jover J, Font-Bardia M, Aullón G, Corbella M. Magnetic Behavior of Heterometallic Wheels Having a [Mn(IV)6M2O9](10+) Core with M = Ca(2+) and Sr(2+). Inorg Chem 2015; 54:11596-605. [PMID: 26645300 DOI: 10.1021/acs.inorgchem.5b02131] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Two new heterometallic Mn(IV)-M(2+) compounds with formula [Mn6M2O9(4-(t)BuC6H4COO)10(4-(t)BuC6H4COOH)5] (M = Ca(2+) (1), Sr(2+) (2)) have been crystallized. The core of both compounds consists of a planar Mn6 ring, where the Mn(IV) ions are alternatively bridged by (μ3-O)2(μ-RCOO) and (μ4-O)(μ-RCOO)2 ligands, and the two alkaline earth ions are located to both sides of the wheel, linked to the oxo bridges, generating three fused [Mn2M2O4](4+) cuboids. These compounds show a net antiferromagnetic behavior, more important for 2 (Sr(2+)) than for 1 (Ca(2+)). The fitting of the experimental data was performed with the support of DFT calculations, considering four different exchange pathways: two between adjacent Mn(IV) ions (J1 and J2) and two between nonadjacent Mn(IV) ions (J3 and J4). The results of the analysis show that J1 and J2 are of the opposite sign, the ferromagnetic contribution corresponding to the [Mn2(μ4-O)(μ-RCOO)2](4+) unit (J2). The influence of the M(2+) ions in the magnetic behavior is analyzed for 1 and 2 and for three hypothetical models with the structural parameters of 1 containing Mg(2+), Sr(2+) or without the M(2+) ions. In spite of the diamagnetic character of the alkaline earth ions, their influence on the magnetic behavior has been evidenced and correlated with their polarizing effect. Moreover, the magnetic interactions between nonadjacent ions are non-negligible.
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Affiliation(s)
| | | | | | - Gabriel Aullón
- Institut de Química Teòrica i Computacional de la Universitat de Barcelona (IQTCUB) , Barcelona 08028, Spain
| | - Montserrat Corbella
- Institut de Nanociencia i Nanotecnologia de la Universitat de Barcelona (IN2UB) , Barcelona 08028, Spain
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188
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Grajeda J, Kita MR, Gregor LC, White PS, Miller AJM. Diverse Cation-Promoted Reactivity of Iridium Carbonyl Pincer-Crown Ether Complexes. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00786] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Javier Grajeda
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Matthew R. Kita
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Lauren C. Gregor
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Peter S. White
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alexander J. M. Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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189
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Chen C, Zhang C, Dong H, Zhao J. Artificial synthetic Mn(IV)Ca-oxido complexes mimic the oxygen-evolving complex in photosystem II. Dalton Trans 2015; 44:4431-5. [PMID: 25662151 DOI: 10.1039/c4dt03459g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel family of heteronuclear Mn(IV)Ca-oxido complexes containing Mn(IV)Ca-oxido cuboidal moieties and reactive water molecules on Ca(2+) have been synthesized and characterized to mimic the oxygen-evolving complex (OEC) of photosystem II (PSII) in nature.
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Affiliation(s)
- Changhui Chen
- Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
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190
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de Ruiter G, Thompson NB, Lionetti D, Agapie T. Nitric oxide activation by distal redox modulation in tetranuclear iron nitrosyl complexes. J Am Chem Soc 2015; 137:14094-106. [PMID: 26390375 DOI: 10.1021/jacs.5b07397] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
A series of tetranuclear iron complexes displaying a site-differentiated metal center was synthesized. Three of the metal centers are coordinated to our previously reported ligand, based on a 1,3,5-triarylbenzene motif with nitrogen and oxygen donors. The fourth (apical) iron center is coordinatively unsaturated and appended to the trinuclear core through three bridging pyrazolates and an interstitial μ4-oxide moiety. Electrochemical studies of complex [LFe3(PhPz)3OFe][OTf]2 revealed three reversible redox events assigned to the Fe(II)4/Fe(II)3Fe(III) (-1.733 V), Fe(II)3Fe(III)/Fe(II)2Fe(III)2 (-0.727 V), and Fe(II)2Fe(III)2/Fe(II)Fe(III)3 (0.018 V) redox couples. Combined Mössbauer and crystallographic studies indicate that the change in oxidation state is exclusively localized at the triiron core, without changing the oxidation state of the apical metal center. This phenomenon is assigned to differences in the coordination environment of the two metal sites and provides a strategy for storing electron and hole equivalents without affecting the oxidation state of the coordinatively unsaturated metal. The presence of a ligand-binding site allowed the effect of redox modulation on nitric oxide activation by an Fe(II) metal center to be studied. Treatment of the clusters with nitric oxide resulted in binding of NO to the apical iron center, generating a {FeNO}(7) moiety. As with the NO-free precursors, the three reversible redox events are localized at the iron centers distal from the NO ligand. Altering the redox state of the triiron core resulted in significant change in the NO stretching frequency, by as much as 100 cm(-1). The increased activation of NO is attributed to structural changes within the clusters, in particular, those related to the interaction of the metal centers with the interstitial atom. The differences in NO activation were further shown to lead to differential reactivity, with NO disproportionation and N2O formation performed by the more electron-rich cluster.
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Affiliation(s)
- Graham de Ruiter
- Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States
| | - Niklas B Thompson
- Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States
| | - Davide Lionetti
- Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States
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191
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Kovacs JA. Tuning the Relative Stability and Reactivity of Manganese Dioxygen and Peroxo Intermediates via Systematic Ligand Modification. Acc Chem Res 2015; 48:2744-53. [PMID: 26335158 DOI: 10.1021/acs.accounts.5b00260] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Many fundamental processes of life depend on the chemical energy stored in the O–O bond of dioxygen (O2), the majority of which is derived from photosynthetic H2O oxidation. Key steps in these processes involve Mn-, Fe-, or Cu-promoted formation or cleavage of O–O and O–H bonds, the mechanisms of which are not fully understood, especially with Mn. Metal–peroxo and high-valent metal–oxo species are proposed to be involved as intermediates. The metal ion properties that favor O–O and O–H bond formation versus cleavage have yet to be systematically explored. Herein we examine the O2 reactivity of a series of structurally related Mn(II) complexes and show that several metastable intermediates are observed, the relative stabilities of which depend on subtle differences in ligand architecture. We show that in contrast to Fe and Cu complexes, O2 binds irreversibly to Mn(II). By crystallizing an entire series of the first reported examples of Mn(III)–OOR peroxos as well as an O2-derived binuclear trans-μ-1,2-bridged Mn(III)–peroxo with varying degrees of O–O bond activation, we demonstrate that there are distinct correlations between spectroscopic, structural, and reactivity properties. Rate-limiting O–O bond cleavage is shown to afford a reactive species capable of abstracting H atoms from 2,4-tBu2-PhOH or 1,4-cyclohexadiene, depending on the ligand substituents. The weakly coordinated N-heterocycle Mn···Npy,quino distance is shown to correlate with the peroxo O–O bond length and modulate the π overlap between the filled πv*(O–O) and Mn dxz orbitals. We also show that there is a strong correlation between the peroxo → Mn charge transfer (CT) band and the peroxo O–O bond length. The energy difference between the CT bands associated with the peroxos possessing the shortest and longest O–O bonds shows that these distances are spectroscopically distinguishable. We show that we can use this spectroscopic parameter to estimate the O–O bond length, and thus the degree of O–O bond activation, in intermediates for which there is no crystal structure, as long as the ligand environment is approximately the same.
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Affiliation(s)
- Julie A. Kovacs
- The Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
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192
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Pyrrol-2-yl-methanone modified silica as electron acceptor for the oxidation of water catalyzed by cobalt(II) complexes. Chem Res Chin Univ 2015. [DOI: 10.1007/s40242-015-5156-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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193
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Cammarota RC, Lu CC. Tuning Nickel with Lewis Acidic Group 13 Metalloligands for Catalytic Olefin Hydrogenation. J Am Chem Soc 2015; 137:12486-9. [DOI: 10.1021/jacs.5b08313] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Ryan C. Cammarota
- Department
of Chemistry and
Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant
Street SE, Minneapolis, Minnesota 55455, United States
| | - Connie C. Lu
- 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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194
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Salamone M, Carboni G, Mangiacapra L, Bietti M. Binding to Redox-Inactive Alkali and Alkaline Earth Metal Ions Strongly Deactivates the C–H Bonds of Tertiary Amides toward Hydrogen Atom Transfer to Reactive Oxygen Centered Radicals. J Org Chem 2015; 80:9214-23. [DOI: 10.1021/acs.joc.5b01661] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Michela Salamone
- Dipartimento
di Scienze e
Tecnologie Chimiche, Università “Tor Vergata”, Via
della Ricerca Scientifica, 1, I-00133 Rome, Italy
| | - Giulia Carboni
- Dipartimento
di Scienze e
Tecnologie Chimiche, Università “Tor Vergata”, Via
della Ricerca Scientifica, 1, I-00133 Rome, Italy
| | - Livia Mangiacapra
- Dipartimento
di Scienze e
Tecnologie Chimiche, Università “Tor Vergata”, Via
della Ricerca Scientifica, 1, I-00133 Rome, Italy
| | - Massimo Bietti
- Dipartimento
di Scienze e
Tecnologie Chimiche, Università “Tor Vergata”, Via
della Ricerca Scientifica, 1, I-00133 Rome, Italy
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195
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Najafpour MM, Ghobadi MZ, Larkum AW, Shen JR, Allakhverdiev SI. The biological water-oxidizing complex at the nano-bio interface. TRENDS IN PLANT SCIENCE 2015; 20:559-68. [PMID: 26183174 DOI: 10.1016/j.tplants.2015.06.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 05/30/2015] [Accepted: 06/16/2015] [Indexed: 05/03/2023]
Abstract
Photosynthesis is one of the most important processes on our planet, providing food and oxygen for the majority of living organisms on Earth. Over the past 30 years scientists have made great strides in understanding the central photosynthetic process of oxygenic photosynthesis, whereby water is used to provide the hydrogen and reducing equivalents vital to CO2 reduction and sugar formation. A recent crystal structure at 1.9-1.95Å has made possible an unparalleled map of the structure of photosystem II (PSII) and particularly the manganese-calcium (Mn-Ca) cluster, which is responsible for splitting water. Here we review how knowledge of the water-splitting site provides important criteria for the design of artificial Mn-based water-oxidizing catalysts, allowing the development of clean and sustainable solar energy technologies.
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Affiliation(s)
- Mohammad Mahdi Najafpour
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran; Center of Climate Change and Global Warming, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran.
| | - Mohadeseh Zarei Ghobadi
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731, Iran
| | - Anthony W Larkum
- Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Sydney, Australia
| | - Jian-Ren Shen
- Photosynthesis Research Center, Graduate School of Natural Science and Technology, Faculty of Science, Okayama University, Okayama 700-8530, Japan
| | - Suleyman I Allakhverdiev
- Controlled Photobiosynthesis Laboratory, Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow 127276, Russia; Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia; Department of Plant Physiology, Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1-12, Moscow 119991, Russia.
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196
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Bonn AG, Wenger OS. Photoinduced charge accumulation by metal ion-coupled electron transfer. Phys Chem Chem Phys 2015; 17:24001-10. [PMID: 26312416 DOI: 10.1039/c5cp04718h] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An oligotriarylamine (OTA) unit, a Ru(bpy)3(2+) photosensitizer moiety (Ru), and an anthraquinone (AQ) entity were combined to a molecular dyad (Ru-OTA) and a molecular triad (AQ-Ru-OTA). Pulsed laser excitation at 532 nm led to the formation of charge-separated states of the type Ru(-)-OTA(+) and AQ(-)-Ru-OTA(+) with lifetimes of ≤10 ns and 2.4 μs, respectively, in de-aerated CH3CN at 25 °C. Upon addition of Sc(OTf)3, very long-lived photoproducts were observed. Under steady-state irradiation conditions using a flux of (6.74 ± 0.21) × 10(15) photons per second at 450 nm, the formation of twofold oxidized oligotriarylamine (OTA(2+)) was detected in aerated CH3CN containing 0.02 M Sc(3+), as demonstrated unambiguously by comparison with UV-Vis absorption spectra obtained in the course of chemical oxidation with Cu(2+). Photodriven charge accumulation on the OTA unit of Ru-OTA and AQ-Ru-OTA is possible due to the lowering of the O2 reduction potential caused by the interaction of superoxide with the strong Lewis acid Sc(3+). The presence of the anthraquinone unit in AQ-Ru-OTA accelerates the rate-determining reaction step for charge accumulation by a factor of 10 compared to the Ru-OTA dyad. This is attributed to the formation of Sc(3+)-stabilized anthraquinone radical anion intermediates in the triad. Possible mechanistic pathways leading to charge accumulation are discussed. Photodriven charge accumulation is of key importance for solar fuels because their production will have to rely on multi-electron chemistry rather than single-electron reaction steps. Our study is the first to demonstrate that metal ion-coupled electron transfer (MCET) can be exploited to accumulate charges on a given molecular unit using visible light as an energy input. The approach of using a combination of intra- and intermolecular electron transfer reactions which are enabled by MCET is conceptually novel, and the fundamental insights gained from our study are relevant in the greater context of solar energy conversion.
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Affiliation(s)
- Annabell G Bonn
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.
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197
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Cook SA, Borovik AS. Molecular designs for controlling the local environments around metal ions. Acc Chem Res 2015; 48:2407-14. [PMID: 26181849 DOI: 10.1021/acs.accounts.5b00212] [Citation(s) in RCA: 232] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The functions of metal complexes are directly linked to the local environment in which they are housed; modifications to the local environment (or secondary coordination sphere) are known to produce changes in key properties of the metal centers that can affect reactivity. Noncovalent interactions are the most common and influential forces that regulate the properties of secondary coordination spheres, which leads to complexities in structure that are often difficult to achieve in synthetic systems. Using key architectural features from the active sites of metalloproteins as inspiration, we have developed molecular systems that enforce intramolecular hydrogen bonds (H-bonds) around a metal center via incorporation of H-bond donors and acceptors into rigid ligand scaffolds. We have utilized these molecular species to probe mechanistic aspects of biological dioxygen activation and water oxidation. This Account describes the stabilization and characterization of unusual M-oxo and heterobimetallic complexes. These types of species have been implicated in a range of oxidative processes in biology but are often difficult to study because of their inherent reactivity. Our H-bonding ligand systems allowed us to prepare an Fe(III)-oxo species directly from the activation of O2 that was subsequently oxidized to form a monomeric Fe(IV)-oxo species with an S = 2 spin state, similar to those species proposed as key intermediates in non-heme monooxygenases. We also demonstrated that a single Mn(III)-oxo center that was prepared from water could be converted to a high-spin Mn(V)-oxo species via stepwise oxidation, a process that mimics the oxidative charging of the oxygen-evolving complex (OEC) of photosystem II. Current mechanisms for photosynthetic O-O bond formation invoke a Mn(IV)-oxyl species rather than the isoelectronic Mn(V)-oxo system as the key oxidant based on computational studies. However, there is no experimental information to support the existence of a Mn-oxyl radical. We therefore probed the amount of spin density on the oxido ligand of our complexes using EPR spectroscopy in conjunction with oxygen-17 labeling. Our findings showed that there is a significant amount of spin on the oxido ligand, yet the M-oxo bonds are best described as highly covalent and there is no indication that an oxyl radical is formed. These results offer the intriguing possibility that high-spin M-oxo complexes are involved in O-O bond formation in biology. Ligand redesign to incorporate H-bond accepting units (sulfonamido groups) simultaneously provided a metal ion binding pocket, adjacent H-bond acceptors, and an auxiliary binding site for a second metal ion. These properties allowed us to isolate a series of heterobimetallic complexes of Fe(III) and Mn(III) in which a group II metal ion was coordinated within the secondary coordination sphere. Examination of the influence of the second metal ion on the electron transfer properties of the primary metal center revealed unexpected similarities between Ca(II) and Sr(II) ions, a result with relevance to the OEC. In addition, the presence of a second metal ion was found to prevent intramolecular oxidation of the ligand with an O atom transfer reagent.
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Affiliation(s)
- Sarah A. Cook
- Department
of Chemistry, University of California—Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - A. S. Borovik
- Department
of Chemistry, University of California—Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
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198
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Semin BK, Davletshina LN, Rubin AB. Correlation between pH dependence of O2 evolution and sensitivity of Mn cations in the oxygen-evolving complex to exogenous reductants. PHOTOSYNTHESIS RESEARCH 2015; 125:95-103. [PMID: 25975707 DOI: 10.1007/s11120-015-0155-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/05/2015] [Indexed: 06/04/2023]
Abstract
Effects of pH, Ca(2+), and Cl(-) ions on the extraction of Mn cations from oxygen-evolving complex (OEC) in Ca-depleted photosystem II (PSII(-Ca)) by exogenous reductants hydroquinone (H2Q) and H2O2 were studied. Two of 4 Mn cations are released by H2Q and H2O2 at pHs 5.7, 6.5, and 7.5, and their extraction does not depend on the presence of Ca(2+) and Cl(-) ions. One of Mn cations ("resistant" Mn cation) cannot be extracted by H2Q and H2O2 at any pH. Extraction of 4th Mn ion ("flexible" Mn cation) is sensitive to pH, Ca(2+), and Cl(-). This Mn cation is released by reductants at pH 6.5 but not at pHs 5.7 and 7.5. A pH dependence curve of the oxygen-evolving activity in PSII(-Ca) membranes (in the presence of exogenous Ca(2+)) has a bell-shaped form with the maximum at pH 6.5. Thus, the increase in the resistance of flexible Mn cation in OEC to the action of reductants at acidic and alkaline pHs coincides with the decrease in oxygen evolution activity at these pHs. Exogenous Ca(2+) protects the extraction of flexible Mn cation at pH 6.5. High concentration of Cl(-) anions (100 mM) shifts the pH optimum of oxygen evolution to alkaline region (around pH 7.5), while the pH of flexible Mn extraction is also shifted to alkaline pH. This result suggests that flexible Mn cation plays a key role in the water-splitting reaction. The obtained results also demonstrate that only one Mn cation in Mn4 cluster is under strong control of calcium. The change in the flexible Mn cation resistance to exogenous reductants in the presence of Ca(2+) suggests that Ca(2+) can control the redox potential of this cation.
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Affiliation(s)
- Boris K Semin
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, 119234, Moscow, Russia,
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199
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Affiliation(s)
- Shunichi Fukuzumi
- Department of Material and Life Science; Graduate School of Engineering; Osaka University, ALCA and SENTAN; Japan Science and Technology Agency (JST); 2-1 Yamada-oka, Suita Osaka 565-0871 Japan
- Department of Bioinspired Science; Ewha Womans University; Seoul 120-750 Korea
- Faculty of Science and Technology; Meijo University and ALCA and SENTAN, Japan Science and Technology Agency (JST); Tempaku Nagoya, Aichi 468-8502 Japan
| | - Kei Ohkubo
- Department of Material and Life Science; Graduate School of Engineering; Osaka University, ALCA and SENTAN; Japan Science and Technology Agency (JST); 2-1 Yamada-oka, Suita Osaka 565-0871 Japan
- Department of Bioinspired Science; Ewha Womans University; Seoul 120-750 Korea
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200
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Svengren H, Hu S, Athanassiadis I, Laine TM, Johnsson M. An Oxofluoride Catalyst Comprised of Transition Metals and a Metalloid for Application in Water Oxidation. Chemistry 2015. [DOI: 10.1002/chem.201501452] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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