1
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Odella E, Moore TA, Moore AL. Tuning the redox potential of tyrosine-histidine bioinspired assemblies. PHOTOSYNTHESIS RESEARCH 2022; 151:185-193. [PMID: 33432530 DOI: 10.1007/s11120-020-00815-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/21/2020] [Indexed: 06/12/2023]
Abstract
Photosynthesis powers our planet and is a source of inspiration for developing artificial constructs mimicking many aspects of the natural energy transducing process. In the complex machinery of photosystem II (PSII), the redox activity of the tyrosine Z (Tyrz) hydrogen-bonded to histidine 190 (His190) is essential for its functions. For example, the Tyrz-His190 pair provides a proton-coupled electron transfer (PCET) pathway that effectively competes against the back-electron transfer reaction and tunes the redox potential of the phenoxyl radical/phenol redox couple ensuring a high net quantum yield of photoinduced charge separation in PSII. Herein, artificial assemblies mimicking both the structural and redox properties of the Tyrz-His190 pair are described. The bioinspired constructs contain a phenol (Tyrz model) covalently linked to a benzimidazole (His190 model) featuring an intramolecular hydrogen bond which closely emulates the one observed in the natural counterpart. Incorporation of electron-withdrawing groups in the benzimidazole moiety systematically changes the intramolecular hydrogen bond strength and modifies the potential of the phenoxyl radical/phenol redox couple over a range of ~ 250 mV. Infrared spectroelectrochemistry (IRSEC) demonstrates the associated one-electron, one-proton transfer (E1PT) process upon electrochemical oxidation of the phenol. The present contribution provides insight regarding the factors controlling the redox potential of the phenol and highlights strategies for the design of futures constructs capable of transporting protons across longer distances while maintaining a high potential of the phenoxyl radical/phenol redox couple.
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Affiliation(s)
- Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287-1604, USA.
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287-1604, USA
| | - Ana L Moore
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287-1604, USA.
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2
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Rao G, Chen N, Marchiori DA, Wang LP, Britt RD. Accumulation and Pulse Electron Paramagnetic Resonance Spectroscopic Investigation of the 4-Oxidobenzyl Radical Generated in the Radical S-Adenosyl-l-methionine Enzyme HydG. Biochemistry 2022; 61:107-116. [PMID: 34989236 DOI: 10.1021/acs.biochem.1c00619] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The radical S-adenosyl-l-methionine (SAM) enzyme HydG cleaves tyrosine to generate CO and CN- ligands of the [FeFe] hydrogenase H-cluster, accompanied by the formation of a 4-oxidobenzyl radical (4-OB•), which is the precursor to the HydG p-cresol byproduct. Native HydG only generates a small amount of 4-OB•, limiting detailed electron paramagnetic resonance (EPR) spectral characterization beyond our initial EPR lineshape study employing various tyrosine isotopologues. Here, we show that the concentration of trapped 4-OB• is significantly increased in reactions using HydG variants, in which the "dangler Fe" to which CO and CN- bind is missing or substituted by a redox-inert Zn2+ ion. This allows for the detailed characterization of 4-OB• using high-field EPR and electron nuclear double resonance spectroscopy to extract its g-values and 1H/13C hyperfine couplings. These results are compared to density functional theory-predicted values of several 4-OB• models with different sizes and protonation states, with a best fit to the deprotonated radical anion configuration of 4-OB•. Overall, our results depict a clearer electronic structure of the transient 4-OB• radical and provide new insights into the radical SAM chemistry of HydG.
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Affiliation(s)
- Guodong Rao
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Nanhao Chen
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - David A Marchiori
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Lee-Ping Wang
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - R David Britt
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
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3
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Odella E, Secor M, Elliott M, Groy TL, Moore TA, Hammes-Schiffer S, Moore AL. Multi PCET in symmetrically substituted benzimidazoles. Chem Sci 2021; 12:12667-12675. [PMID: 34703552 PMCID: PMC8494046 DOI: 10.1039/d1sc03782j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 08/21/2021] [Indexed: 12/02/2022] Open
Abstract
Proton-coupled electron transfer (PCET) reactions depend on the hydrogen-bond connectivity between sites of proton donors and acceptors. The 2-(2′-hydroxyphenyl) benzimidazole (BIP) based systems, which mimic the natural TyrZ-His190 pair of Photosystem II, have been useful for understanding the associated PCET process triggered by one-electron oxidation of the phenol. Substitution of the benzimidazole by an appropriate terminal proton acceptor (TPA) group allows for two-proton translocations. However, the prototropic properties of substituted benzimidazole rings and rotation around the bond linking the phenol and the benzimidazole can lead to isomers that interrupt the intramolecular hydrogen-bonded network and thereby prevent a second proton translocation. Herein, a strategic symmetrization of a benzimidazole based system with two identical TPAs yields an uninterrupted network of intramolecular hydrogen bonds regardless of the isomeric form. NMR data confirms the presence of a single isomeric form in the disubstituted system but not in the monosubstituted system in certain solvents. Infrared spectroelectrochemistry demonstrates a two-proton transfer process associated with the oxidation of the phenol occurring at a lower redox potential in the disubstituted system relative to its monosubstituted analogue. Computational studies support these findings and show that the disubstituted system stabilizes the oxidized two-proton transfer product through the formation of a bifurcated hydrogen bond. Considering the prototropic properties of the benzimidazole heterocycle in the context of multiple PCET will improve the next generation of novel, bioinspired constructs built by concatenated units of benzimidazoles, thus allowing proton translocations at nanoscale length. Proton-coupled electron transfer (PCET) reactions depend on the hydrogen-bond connectivity between sites of proton donors and acceptors.![]()
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Affiliation(s)
- Emmanuel Odella
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Maxim Secor
- Department of Chemistry, Yale University New Haven Connecticut 06520-8107 USA
| | - Mackenna Elliott
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Thomas L Groy
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
| | | | - Ana L Moore
- School of Molecular Sciences, Arizona State University Tempe Arizona 85287-1604 USA
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4
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Weitkamp RF, Neumann B, Stammler H, Hoge B. Non-coordinated and Hydrogen Bonded Phenolate Anions as One-Electron Reducing Agents. Chemistry 2021; 27:6465-6478. [PMID: 33368714 PMCID: PMC8247865 DOI: 10.1002/chem.202005123] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 12/22/2020] [Indexed: 11/29/2022]
Abstract
In this work, the syntheses of non-coordinated electron-rich phenolate anions via deprotonation of the corresponding alcohols with an extremely powerful perethyl tetraphosphazene base (Schwesinger base) are reported. The application of uncharged phosphazenes renders the selective preparation of anionic phenol-phenolate and phenolate hydrates possible, which allows for the investigation of hydrogen bonding in these species. Hydrogen bonding brings about decreased redox potentials relative to the corresponding non-coordinated phenolate anions. The latter show redox potentials of up to -0.72(1) V vs. SCE, which is comparable to that of zinc metal, thus qualifying their application as organic zinc mimics. We utilized phenolates as reducing agents for the generation of radical anions in addition to the corresponding phenoxyl radicals. A tetracyanoethylene radical anion salt was synthesized and fully characterized as a representative example. We also present the activation of sulfur hexafluoride (SF6 ) with phenolates in a SET reaction, in which the nature of the respective phenolate determines whether simple fluorides or pentafluorosulfanide ([SF5 ]- ) salts are formed.
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Affiliation(s)
- Robin F. Weitkamp
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Beate Neumann
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Berthold Hoge
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
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5
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Guerra WD, Odella E, Secor M, Goings JJ, Urrutia MN, Wadsworth BL, Gervaldo M, Sereno LE, Moore TA, Moore GF, Hammes-Schiffer S, Moore AL. Role of Intact Hydrogen-Bond Networks in Multiproton-Coupled Electron Transfer. J Am Chem Soc 2020; 142:21842-21851. [DOI: 10.1021/jacs.0c10474] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Walter D. Guerra
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Maxim Secor
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Joshua J. Goings
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - María N. Urrutia
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Brian L. Wadsworth
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Miguel Gervaldo
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Agencia Postal No. 3, 5800 Río Cuarto, Córdoba, Argentina
| | - Leónides E. Sereno
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Agencia Postal No. 3, 5800 Río Cuarto, Córdoba, Argentina
| | - Thomas A. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Gary F. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Ana L. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
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6
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Mardis KL, Niklas J, Omodayo H, Odella E, Moore TA, Moore AL, Poluektov OG. One Electron Multiple Proton Transfer in Model Organic Donor-Acceptor Systems: Implications for High Frequency EPR. APPLIED MAGNETIC RESONANCE 2020; 51:977-991. [PMID: 34764625 PMCID: PMC8579843 DOI: 10.1007/s00723-020-01252-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 08/03/2020] [Indexed: 06/12/2023]
Abstract
EPR spectroscopy is an important spectroscopic method for identification and characterization of radical species involved in many biological reactions. The tyrosyl radical is one of the most studied amino acid radical intermediates in biology. Often in conjunction with histidine residues, it is involved in many fundamental biological electron and proton transfer processes, such as in the water oxidation in photosystem II. As biological processes are typically extremely complicated and hard to control, molecular bio-mimetic model complexes are often used to clarify the mechanisms of the biological reactions. Here we present theoretical calculations to investigate the sensitivity of magnetic resonance parameters to proton-coupled electron transfer events, as well as conformational substates of the molecular constructs which mimic the tyrosine-histidine (Tyr-His) pairs found in a large variety of proteins. Upon oxidation of the phenol, the Tyr analogue, these complexes can perform not only one-electron one-proton transfer (EPT), but also one-electron two-proton transfers (E2PT). It is shown that in aprotic environment the gX-components of the electronic g-tensor are extremely sensitive to the first proton transfer from the phenoxyl oxygen to the imidazole nitrogen (EPT product), leading to a significant increase of the gX-value of up to 0.003, but are not sensitive to the second proton transfer (E2PT product). In the latter case the change of the gX-value is much smaller (ca. 0.0001), which is too small to be distinguished even by high frequency EPR. The 14N hyperfine values are also too similar to allow differentiation between the different protonation states in EPT and E2PT. The magnetic resonance parameters were also calculated as a function of the rotation angles around single bonds. It was demonstrated that rotation of the phenoxyl group results in large positive changes (>0.001) in the gX-values. Analysis of the data reveals that the main source of these changes is related to the strength of the H-bond between phenoxyl oxygen and the proton(s) on N1 and N2 positions of the imidazole.
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Affiliation(s)
- Kristy L Mardis
- Department of Chemistry, Physics, and Engineering Studies, Chicago State University, Chicago, Illinois 60628, USA
| | - Jens Niklas
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Harriet Omodayo
- Department of Chemistry, Physics, and Engineering Studies, Chicago State University, Chicago, Illinois 60628, USA
| | - Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, 85287, USA
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, 85287, USA
| | - Ana L Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, 85287, USA
| | - Oleg G Poluektov
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
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7
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Goings JJ, Hammes-Schiffer S. Nonequilibrium Dynamics of Proton-Coupled Electron Transfer in Proton Wires: Concerted but Asynchronous Mechanisms. ACS CENTRAL SCIENCE 2020; 6:1594-1601. [PMID: 32999935 PMCID: PMC7517869 DOI: 10.1021/acscentsci.0c00756] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Indexed: 05/29/2023]
Abstract
The coupling between electrons and protons and the long-range transport of protons play important roles throughout biology. Biomimetic systems derived from benzimidazole-phenol (BIP) constructs have been designed to undergo proton-coupled electron transfer (PCET) upon electrochemical or photochemical oxidation. Moreover, these systems can transport protons along hydrogen-bonded networks or proton wires through multiproton PCET. Herein, the nonequilibrium dynamics of both single and double proton transfer in BIP molecules initiated by oxidation are investigated with first-principles molecular dynamics simulations. Although these processes are concerted in that no thermodynamically stable intermediate is observed, the simulations predict that they are predominantly asynchronous on the ultrafast time scale. For both systems, the first proton transfer typically occurs ∼100 fs after electron transfer. For the double proton transfer system, typically the second proton transfer occurs hundreds of femtoseconds after the initial proton transfer. A machine learning algorithm was used to identify the key molecular vibrational modes essential for proton transfer: a slow, in-plane bending mode that dominates the overall inner-sphere reorganization, the proton donor-acceptor motion that leads to vibrational coherence, and the faster donor-hydrogen stretching mode. The asynchronous double proton transfer mechanism can be understood in terms of a significant mode corresponding to the two anticorrelated proton donor-acceptor motions, typically decreasing only one donor-acceptor distance at a time. Although these PCET processes appear concerted on the time scale of typical electrochemical experiments, attaching these BIP constructs to photosensitizers may enable the detection of the asynchronicity of the electron and multiple proton transfers with ultrafast two-dimensional spectroscopy. Understanding the fundamental PCET mechanisms at this level will guide the design of PCET systems for catalysis and energy conversion processes.
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Affiliation(s)
- Joshua J. Goings
- Department of Chemistry, Yale University, 225
Prospect Street, New Haven, Connecticut 06520, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, 225
Prospect Street, New Haven, Connecticut 06520, United States
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8
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Méndez-Hernández DD, Baldansuren A, Kalendra V, Charles P, Mark B, Marshall W, Molnar B, Moore TA, Lakshmi KV, Moore AL. HYSCORE and DFT Studies of Proton-Coupled Electron Transfer in a Bioinspired Artificial Photosynthetic Reaction Center. iScience 2020; 23:101366. [PMID: 32738611 PMCID: PMC7394912 DOI: 10.1016/j.isci.2020.101366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 06/22/2020] [Accepted: 07/10/2020] [Indexed: 11/24/2022] Open
Abstract
The photosynthetic water-oxidation reaction is catalyzed by the oxygen-evolving complex in photosystem II (PSII) that comprises the Mn4CaO5 cluster, with participation of the redox-active tyrosine residue (YZ) and a hydrogen-bonded network of amino acids and water molecules. It has been proposed that the strong hydrogen bond between YZ and D1-His190 likely renders YZ kinetically and thermodynamically competent leading to highly efficient water oxidation. However, a detailed understanding of the proton-coupled electron transfer (PCET) at YZ remains elusive owing to the transient nature of its intermediate states involving YZ⋅. Herein, we employ a combination of high-resolution two-dimensional 14N hyperfine sublevel correlation spectroscopy and density functional theory methods to investigate a bioinspired artificial photosynthetic reaction center that mimics the PCET process involving the YZ residue of PSII. Our results underscore the importance of proximal water molecules and charge delocalization on the electronic structure of the artificial reaction center. Structural factors are critical in the design of artificial photosynthetic systems Correlation between hyperfine couplings of the N atoms and electron spin density Spin density distribution affected by charge delocalization and explicit waters Spin density modulation by electronic coupling as observed with P680 and YZ in PSII
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Affiliation(s)
| | - Amgalanbaatar Baldansuren
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Vidmantas Kalendra
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Philip Charles
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Brian Mark
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - William Marshall
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Brian Molnar
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Thomas A Moore
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - K V Lakshmi
- Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
| | - Ana L Moore
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA.
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9
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Samanta D, Saha P, Ghosh P. Proton-Coupled Oxidation of Aldimines and Stabilization of H-Bonded Phenoxyl Radical-Phenol Skeletons. Inorg Chem 2019; 58:15060-15077. [DOI: 10.1021/acs.inorgchem.9b01568] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Debasish Samanta
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata 700103, India
| | - Pinaki Saha
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata 700103, India
| | - Prasanta Ghosh
- Department of Chemistry, R. K. Mission Residential College, Narendrapur, Kolkata 700103, India
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10
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Odella E, Wadsworth BL, Mora SJ, Goings JJ, Huynh MT, Gust D, Moore TA, Moore GF, Hammes-Schiffer S, Moore AL. Proton-Coupled Electron Transfer Drives Long-Range Proton Translocation in Bioinspired Systems. J Am Chem Soc 2019; 141:14057-14061. [DOI: 10.1021/jacs.9b06978] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Brian L. Wadsworth
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - S. Jimena Mora
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Joshua J. Goings
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Mioy T. Huynh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Devens Gust
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Thomas A. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Gary F. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Ana L. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
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11
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Sirohiwal A, Neese F, Pantazis DA. Microsolvation of the Redox-Active Tyrosine-D in Photosystem II: Correlation of Energetics with EPR Spectroscopy and Oxidation-Induced Proton Transfer. J Am Chem Soc 2019; 141:3217-3231. [PMID: 30666866 PMCID: PMC6728127 DOI: 10.1021/jacs.8b13123] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photosystem II (PSII) of oxygenic photosynthesis captures sunlight to drive the catalytic oxidation of water and the reduction of plastoquinone. Among the several redox-active cofactors that participate in intricate electron transfer pathways there are two tyrosine residues, YZ and YD. They are situated in symmetry-related electron transfer branches but have different environments and play distinct roles. YZ is the immediate oxidant of the oxygen-evolving Mn4CaO5 cluster, whereas YD serves regulatory and protective functions. The protonation states and hydrogen-bond network in the environment of YD remain debated, while the role of microsolvation in stabilizing different redox states of YD and facilitating oxidation or mediating deprotonation, as well the fate of the phenolic proton, is unclear. Here we present detailed structural models of YD and its environment using large-scale quantum mechanical models and all-atom molecular dynamics of a complete PSII monomer. The energetics of water distribution within a hydrophobic cavity adjacent to YD are shown to correlate directly with electron paramagnetic resonance (EPR) parameters such as the tyrosyl g-tensor, allowing us to map the correspondence between specific structural models and available experimental observations. EPR spectra obtained under different conditions are explained with respect to the mode of interaction of the proximal water with the tyrosyl radical and the position of the phenolic proton within the cavity. Our results revise previous models of the energetics and build a detailed view of the role of confined water in the oxidation and deprotonation of YD. Finally, the model of microsolvation developed in the present work rationalizes in a straightforward way the biphasic oxidation kinetics of YD, offering new structural insights regarding the function of the radical in biological photosynthesis.
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Affiliation(s)
- Abhishek Sirohiwal
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , 45470 Mülheim an der Ruhr , Germany
- Fakultät für Chemie und Biochemie , Ruhr-Universität Bochum , 44780 Bochum , Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , 45470 Mülheim an der Ruhr , Germany
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , 45470 Mülheim an der Ruhr , Germany
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12
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Glasbrenner M, Vogler S, Ochsenfeld C. Linear and sublinear scaling computation of the electronic g-tensor at the density functional theory level. J Chem Phys 2019; 150:024104. [DOI: 10.1063/1.5066266] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Michael Glasbrenner
- Chair of Theoretical Chemistry and Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, 81377 Munich, Germany
| | - Sigurd Vogler
- Chair of Theoretical Chemistry and Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, 81377 Munich, Germany
| | - Christian Ochsenfeld
- Chair of Theoretical Chemistry and Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, 81377 Munich, Germany
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13
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Cinar ME, Lal M, Deiseroth HJ, Schlirf J, Schmittel M. Detection and follow-up reactions of distonic β
, β
-dimesityl enol radical cations containing nitrogen heterocyclic bases. J PHYS ORG CHEM 2018. [DOI: 10.1002/poc.3865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- M. Emin Cinar
- Department Chemie-Biologie; Universität Siegen; Siegen Germany
| | - Mukul Lal
- Department Chemie-Biologie; Universität Siegen; Siegen Germany
| | | | - Jens Schlirf
- Department Chemie-Biologie; Universität Siegen; Siegen Germany
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14
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Odella E, Mora SJ, Wadsworth BL, Huynh MT, Goings JJ, Liddell PA, Groy TL, Gervaldo M, Sereno LE, Gust D, Moore TA, Moore GF, Hammes-Schiffer S, Moore AL. Controlling Proton-Coupled Electron Transfer in Bioinspired Artificial Photosynthetic Relays. J Am Chem Soc 2018; 140:15450-15460. [DOI: 10.1021/jacs.8b09724] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - S. Jimena Mora
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Brian L. Wadsworth
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Mioy T. Huynh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Joshua J. Goings
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Paul A. Liddell
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Thomas L. Groy
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Miguel Gervaldo
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Agencia Postal No. 3, 5800 Río Cuarto, Córdoba, Argentina
| | - Leónides E. Sereno
- Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Agencia Postal No. 3, 5800 Río Cuarto, Córdoba, Argentina
| | - Devens Gust
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Thomas A. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Gary F. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Ana L. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, United States
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15
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Chararalambidis G, Das S, Trapali A, Quaranta A, Orio M, Halime Z, Fertey P, Guillot R, Coutsolelos A, Leibl W, Aukauloo A, Sircoglou M. Water Molecules Gating a Photoinduced One-Electron Two-Protons Transfer in a Tyrosine/Histidine (Tyr/His) Model of Photosystem II. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201804498] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Georgios Chararalambidis
- Laboratory of Bioinorganic Chemistry; Chemistry Department; University of Crete; PO Box 2208 71003 Heraklion Crete Greece
| | - Shyamal Das
- Institut des Sciences du vivant Frédéric Joliot/Institut de Biologie Intégrative de la Cellule, UMR 9198; CEA; CNRS; Université Paris Sud; Université Paris-Saclay; 91191 Gif-sur-Yvette France
| | - Adelais Trapali
- Laboratory of Bioinorganic Chemistry; Chemistry Department; University of Crete; PO Box 2208 71003 Heraklion Crete Greece
| | - Annamaria Quaranta
- Institut des Sciences du vivant Frédéric Joliot/Institut de Biologie Intégrative de la Cellule, UMR 9198; CEA; CNRS; Université Paris Sud; Université Paris-Saclay; 91191 Gif-sur-Yvette France
| | - Maylis Orio
- Aix Marseille Univ; iSm2; CNRS; Cent Marseille; 13397 Marseille France
| | - Zakaria Halime
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR 8182 CNRS; Université Paris Sud; Université Paris-Saclay; 91405 Orsay France
| | - Pierre Fertey
- Synchrotron SOLEIL; BP 48, L'Orme des Merisiers, Saint Aubin 91192 Gif-sur-Yvette Cedex France
| | - Régis Guillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR 8182 CNRS; Université Paris Sud; Université Paris-Saclay; 91405 Orsay France
| | - Athanassios Coutsolelos
- Laboratory of Bioinorganic Chemistry; Chemistry Department; University of Crete; PO Box 2208 71003 Heraklion Crete Greece
| | - Winfried Leibl
- Institut des Sciences du vivant Frédéric Joliot/Institut de Biologie Intégrative de la Cellule, UMR 9198; CEA; CNRS; Université Paris Sud; Université Paris-Saclay; 91191 Gif-sur-Yvette France
| | - Ally Aukauloo
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR 8182 CNRS; Université Paris Sud; Université Paris-Saclay; 91405 Orsay France
- Institut des Sciences du vivant Frédéric Joliot/Institut de Biologie Intégrative de la Cellule, UMR 9198; CEA; CNRS; Université Paris Sud; Université Paris-Saclay; 91191 Gif-sur-Yvette France
| | - Marie Sircoglou
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR 8182 CNRS; Université Paris Sud; Université Paris-Saclay; 91405 Orsay France
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16
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Chararalambidis G, Das S, Trapali A, Quaranta A, Orio M, Halime Z, Fertey P, Guillot R, Coutsolelos A, Leibl W, Aukauloo A, Sircoglou M. Water Molecules Gating a Photoinduced One-Electron Two-Protons Transfer in a Tyrosine/Histidine (Tyr/His) Model of Photosystem II. Angew Chem Int Ed Engl 2018; 57:9013-9017. [DOI: 10.1002/anie.201804498] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Georgios Chararalambidis
- Laboratory of Bioinorganic Chemistry; Chemistry Department; University of Crete; PO Box 2208 71003 Heraklion Crete Greece
| | - Shyamal Das
- Institut des Sciences du vivant Frédéric Joliot/Institut de Biologie Intégrative de la Cellule, UMR 9198; CEA; CNRS; Université Paris Sud; Université Paris-Saclay; 91191 Gif-sur-Yvette France
| | - Adelais Trapali
- Laboratory of Bioinorganic Chemistry; Chemistry Department; University of Crete; PO Box 2208 71003 Heraklion Crete Greece
| | - Annamaria Quaranta
- Institut des Sciences du vivant Frédéric Joliot/Institut de Biologie Intégrative de la Cellule, UMR 9198; CEA; CNRS; Université Paris Sud; Université Paris-Saclay; 91191 Gif-sur-Yvette France
| | - Maylis Orio
- Aix Marseille Univ; iSm2; CNRS; Cent Marseille; 13397 Marseille France
| | - Zakaria Halime
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR 8182 CNRS; Université Paris Sud; Université Paris-Saclay; 91405 Orsay France
| | - Pierre Fertey
- Synchrotron SOLEIL; BP 48, L'Orme des Merisiers, Saint Aubin 91192 Gif-sur-Yvette Cedex France
| | - Régis Guillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR 8182 CNRS; Université Paris Sud; Université Paris-Saclay; 91405 Orsay France
| | - Athanassios Coutsolelos
- Laboratory of Bioinorganic Chemistry; Chemistry Department; University of Crete; PO Box 2208 71003 Heraklion Crete Greece
| | - Winfried Leibl
- Institut des Sciences du vivant Frédéric Joliot/Institut de Biologie Intégrative de la Cellule, UMR 9198; CEA; CNRS; Université Paris Sud; Université Paris-Saclay; 91191 Gif-sur-Yvette France
| | - Ally Aukauloo
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR 8182 CNRS; Université Paris Sud; Université Paris-Saclay; 91405 Orsay France
- Institut des Sciences du vivant Frédéric Joliot/Institut de Biologie Intégrative de la Cellule, UMR 9198; CEA; CNRS; Université Paris Sud; Université Paris-Saclay; 91191 Gif-sur-Yvette France
| | - Marie Sircoglou
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR 8182 CNRS; Université Paris Sud; Université Paris-Saclay; 91405 Orsay France
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17
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Mora SJ, Odella E, Moore GF, Gust D, Moore TA, Moore AL. Proton-Coupled Electron Transfer in Artificial Photosynthetic Systems. Acc Chem Res 2018; 51:445-453. [PMID: 29309118 DOI: 10.1021/acs.accounts.7b00491] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Artificial photosynthetic constructs can in principle operate more efficiently than natural photosynthesis because they can be rationally designed to optimize solar energy conversion for meeting human demands rather than the multiple needs of an organism competing for growth and reproduction in a complex ecosystem. The artificial photosynthetic constructs described in this Account consist primarily of covalently linked synthetic chromophores, electron donors and acceptors, and proton donors and acceptors that carry out the light absorption, electron transfer, and proton-coupled electron transfer (PCET) processes characteristic of photosynthetic cells. PCET is the movement of an electron from one site to another accompanied by proton transfer. PCET and the transport of protons over tens of angstroms are important in all living cells because they are a fundamental link between redox processes and the establishment of transmembrane gradients of proton electrochemical potential, known as proton-motive force (PMF), which is the unifying concept in bioenergetics. We have chosen a benzimidazole phenol (BIP) system as a platform for the study of PCET because with appropriate substitutions it is possible to design assemblies in which one or multiple proton transfers can accompany oxidation of the phenol. In BIP, oxidation of the phenol increases its acidity by more than ten pKa units; thus, electrochemical oxidation of the phenol is associated with a proton transfer to the imidazole. This is an example of a PCET process involving transfer of one electron and one proton, known as electron-proton transfer (EPT). When the benzimidazole moiety of BIP is substituted at the 4-position with good proton acceptor groups such as aliphatic amines, experimental and theoretical results indicate that two proton transfers occur upon one-electron oxidation of the phenol. This phenomenon is described as a one-electron-two-proton transfer (E2PT) process and results in translocation of protons over ∼7 Å via a Grotthuss-type mechanism, where the protons traverse a network of internally H-bonded sites. In the case of the E2TP process involving BIP analogues with amino group substituents, the thermodynamic price paid in redox potential to move a proton to the final proton acceptor is ∼300 mV. In this example, the decrease in redox potential limits the oxidizing power of the resulting phenoxyl radical. Thus, unlike the biological counterpart, the artificial construct is thermodynamically incapable of effectively advancing the redox state of a water oxidation catalyst. The design of systems where multiple proton transfer events are coupled to an oxidation reaction while a relatively high redox potential is maintained remains an outstanding challenge. The ability to control proton transfer and activity at defined distances and times is key to achieving proton management in the vicinity of catalysts operating at low overpotential in myriad biochemically important processes. Artificial photosynthetic constructs with well-defined structures, such as the ones described in this Account, can provide the means for discovering design principles upon which efficient redox catalysts for electrolysis and fuel cells can be based.
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Affiliation(s)
- S. Jimena Mora
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Emmanuel Odella
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Gary F. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Devens Gust
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Thomas A. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Ana L. Moore
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
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18
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Beal NJ, Corry TA, O'Malley PJ. A Comparison of Experimental and Broken Symmetry Density Functional Theory (BS-DFT) Calculated Electron Paramagnetic Resonance (EPR) Parameters for Intermediates Involved in the S 2 to S 3 State Transition of Nature's Oxygen Evolving Complex. J Phys Chem B 2018; 122:1394-1407. [PMID: 29300480 DOI: 10.1021/acs.jpcb.7b10843] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A broken symmetry density functional theory (BS-DFT) magnetic analysis of the S2, S2YZ•, and S3 states of Nature's oxygen evolving complex is performed for both the native Ca and Sr substituted forms. Good agreement with experiment is observed between the tyrosyl calculated g-tensor and 1H hyperfine couplings for the native Ca form. Changes in the hydrogen bonding environment of the tyrosyl radical in S2YZ• caused by Sr substitution lead to notable changes in the calculated g-tensor of the tyrosyl radical. Comparison of calculated and experimental 55Mn hyperfine couplings for the S3 state presently favors an open cubane form of the complex with an additional OH ligand coordinating to MnD. In Ca models, this additional ligation can arise by closed-cubane form deprotonation of the Ca ligand W3 in the S2YZ• state accompanied by spontaneous movement to the vacant Mn coordination site or by addition of an external OH group. For the Sr form, no spontaneous movement of W3 to the vacant Mn coordination site is observed in contrast to the native Ca form, a difference which may lead to the reduced catalytic activity of the Sr substituted form. BS-DFT studies on peroxo models of S3 as indicated by a recent X-ray free electron laser (XFEL) crystallography study give rise to a structural model compatible with experimental data and an S = 3 ground state compatible with EPR studies.
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Affiliation(s)
- Nathan J Beal
- School of Chemistry, The University of Manchester , Manchester M13 9PL, U.K
| | - Thomas A Corry
- School of Chemistry, The University of Manchester , Manchester M13 9PL, U.K
| | - Patrick J O'Malley
- School of Chemistry, The University of Manchester , Manchester M13 9PL, U.K
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19
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Weissman A, Amir D, Elias Y, Pinkas I, Mathias JL, Benisvy L, Salomon A. Bio-inspired Photocatalytic Ruthenium Complexes: Synthesis, Optical Properties, and Solvatochromic Effect. Chemphyschem 2018; 19:220-226. [PMID: 29194896 DOI: 10.1002/cphc.201701061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 11/27/2017] [Indexed: 11/11/2022]
Abstract
We report the synthesis, characterization, and photo-physical properties of two new rutheniumII -phenol-imidazole complexes. These bio-mimetic complexes have potential as photocatalysts for water splitting. Owing to their multiple phenol-imidazole groups, they have a higher probability of light-induced radical formation than existing complexes. The newly synthesized complexes show improved overlap with the solar spectrum compared to other rutheniumII -phenol-imidazole complexes, and their measured lifetimes are suitable for light-induced radical formation. In addition, we conducted solvatochromic absorption measurements, which elegantly follow Marcus theory, and demonstrate the symmetry differences between the two complexes. The solvatochromic measurements further imply electron localization onto one of the ligands. The new complexes may find applications in photocatalysis, dye-sensitized solar cells, biomedicine, and sensing. Moreover, their multiple chelating units make them promising candidates for light-activated metal organic radical frameworks, i.e. metal-organic frameworks that contain organic radicals activated by light.
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Affiliation(s)
- Adam Weissman
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Dan Amir
- Department of Life Sciences, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Yuval Elias
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Iddo Pinkas
- Faculty of Chemistry, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Jenny-Lee Mathias
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Laurent Benisvy
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Adi Salomon
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat-Gan, 5290002, Israel
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20
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Chemically induced dynamic nuclear polarization study of the reduction of histidine radical in the reactions with aromatic amino acids. Russ Chem Bull 2017. [DOI: 10.1007/s11172-016-1676-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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21
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Markle TF, Zhang MT, Santoni MP, Johannissen LO, Hammarström L. Proton-Coupled Electron Transfer in a Series of Ruthenium-Linked Tyrosines with Internal Bases: Evaluation of a Tunneling Model for Experimental Temperature-Dependent Kinetics. J Phys Chem B 2016; 120:9308-21. [DOI: 10.1021/acs.jpcb.6b05885] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Todd F. Markle
- Department of Chemistry − Ångström
Laboratory, Uppsala University, P.O. Box 523, S-75120 Uppsala, Sweden
| | - Ming-Tian Zhang
- Department of Chemistry − Ångström
Laboratory, Uppsala University, P.O. Box 523, S-75120 Uppsala, Sweden
| | - Marie-Pierre Santoni
- Department of Chemistry − Ångström
Laboratory, Uppsala University, P.O. Box 523, S-75120 Uppsala, Sweden
| | - Linus O. Johannissen
- Department of Chemistry − Ångström
Laboratory, Uppsala University, P.O. Box 523, S-75120 Uppsala, Sweden
| | - Leif Hammarström
- Department of Chemistry − Ångström
Laboratory, Uppsala University, P.O. Box 523, S-75120 Uppsala, Sweden
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22
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Eckshtain-Levi M, Lavi R, Yufit DS, Daniel B, Green O, Fleker O, Richman M, Rahimipour S, Gruzman A, Benisvy L. A versatile water-soluble chelating and radical scavenging platform. Chem Commun (Camb) 2016; 52:2350-3. [DOI: 10.1039/c5cc08198j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The reported water-soluble, non-cytotoxic phenol-diamide compound, 1OH, is capable of both, trapping ROS species and chelating Cu(ii)/Fe(iii) ions; thereby inducing a protective effect against ROS induced cell death.
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Affiliation(s)
| | - Ronit Lavi
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | | | - Bareket Daniel
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Omer Green
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Ohad Fleker
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Michal Richman
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Shai Rahimipour
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Arie Gruzman
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Laurent Benisvy
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
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23
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Parween A, Mandal TK, Guillot R, Naskar S. Acid–base behavior, electrochemical properties and DFT study of redox non-innocent phenol–imidazole ligands and their Cu complexes. Polyhedron 2015. [DOI: 10.1016/j.poly.2015.06.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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24
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Liu Y, Liu H, Song K, Xu Y, Shi Q. Theoretical Study of Proton Coupled Electron Transfer Reactions: The Effect of Hydrogen Bond Bending Motion. J Phys Chem B 2015; 119:8104-14. [DOI: 10.1021/acs.jpcb.5b02927] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yang Liu
- Beijing
National Laboratory
for Molecular Sciences, State Key Laboratory for Structural Chemistry
of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, China
| | - Hao Liu
- Beijing
National Laboratory
for Molecular Sciences, State Key Laboratory for Structural Chemistry
of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, China
| | - Kai Song
- Beijing
National Laboratory
for Molecular Sciences, State Key Laboratory for Structural Chemistry
of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, China
| | - Yang Xu
- Beijing
National Laboratory
for Molecular Sciences, State Key Laboratory for Structural Chemistry
of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, China
| | - Qiang Shi
- Beijing
National Laboratory
for Molecular Sciences, State Key Laboratory for Structural Chemistry
of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, China
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25
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Retegan M, Cox N, Lubitz W, Neese F, Pantazis DA. The first tyrosyl radical intermediate formed in the S2-S3 transition of photosystem II. Phys Chem Chem Phys 2015; 16:11901-10. [PMID: 24760184 DOI: 10.1039/c4cp00696h] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The EPR "split signals" represent key intermediates of the S-state cycle where the redox active D1-Tyr161 (YZ) has been oxidized by the reaction center of the photosystem II enzyme to its tyrosyl radical form, but the successive oxidation of the Mn4CaO5 cluster has not yet occurred (SiYZ˙). Here we focus on the S2YZ˙ state, which is formed en route to the final metastable state of the catalyst, the S3 state, the state which immediately precedes O-O bond formation. Quantum chemical calculations demonstrate that both isomeric forms of the S2 state, the open and closed cubane isomers, can form states with an oxidized YZ˙ residue without prior deprotonation of the Mn4CaO5 cluster. The two forms are expected to lie close in energy and retain the electronic structure and magnetic topology of the corresponding S2 state of the inorganic core. As expected, tyrosine oxidation results in a proton shift towards His190. Analysis of the electronic rearrangements that occur upon formation of the tyrosyl radical suggests that a likely next step in the catalytic cycle is the deprotonation of a terminal water ligand (W1) of the Mn4CaO5 cluster. Diamagnetic metal ion substitution is used in our calculations to obtain the molecular g-tensor of YZ˙. It is known that the gx value is a sensitive probe not only of the extent of the proton shift between the tyrosine-histidine pair, but also of the polarization environment of the tyrosine, especially about the phenolic oxygen. It is shown for PSII that this environment is determined by the Ca(2+) ion, which locates two water molecules about the phenoxyl oxygen, indirectly modulating the oxidation potential of YZ.
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Affiliation(s)
- Marius Retegan
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-38, 45470 Mülheim an der Ruhr, Germany.
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26
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Trefz T, Kabir MK, Jain R, Patrick BO, Hicks RG. Unconventional redox properties of hydroquinones with intramolecular OH−N hydrogen bonds. CAN J CHEM 2014. [DOI: 10.1139/cjc-2014-0175] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The redox (chemical and electrochemical) properties of several hydroquinones are reported in which the OH protons are engaged in intramolecular hydrogen bonds to a nitrogen-based acceptor (pyridine or amine). The 1,4-hydroquinones generally undergo reversible oxidation to quinones in which both OH protons have transferred to the pendant bases; the oxidation processes are generally chemically and electrochemically reversible, in stark contrast with normal hydroquinones, which are oxidized irreversibly (via proton loss) to quinones. The oxidation processes, believed to occur in concerted proton/electron transfer steps, are at much lower potentials for the hydrogen-bonded derivatives relative to unsubstituted derivatives. In contrast, isomeric 1,3-hydroquinones (resorcinols) are oxidized irreversibly at relatively high potentials. The stability of some of the 1,4-hydroquinone oxidized species permits their isolation and characterization both spectroscopically and structurally. Somewhat surprisingly, in the oxidized species in which the proton is now located on the nitrogen base, the characterization data indicate that there is no NH−O hydrogen bond. Relationships between the particulars of the redox properties of the hydroquinones (potentials, reversibility/stability) and molecular structure are discussed.
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Affiliation(s)
- Tyler Trefz
- Department of Chemistry, University of Victoria, P.O. Box 3065 STN CSC, Victoria, BC V8W 3V6, Canada
| | - Md. Khayrul Kabir
- Department of Chemistry, University of Victoria, P.O. Box 3065 STN CSC, Victoria, BC V8W 3V6, Canada
| | - Rajsapan Jain
- Department of Chemistry, University of Victoria, P.O. Box 3065 STN CSC, Victoria, BC V8W 3V6, Canada
| | - Brian O. Patrick
- Crystallography Laboratory, Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Robin G. Hicks
- Department of Chemistry, University of Victoria, P.O. Box 3065 STN CSC, Victoria, BC V8W 3V6, Canada
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27
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El Ghachtouli S, Lassalle‐Kaiser B, Guillot R, Aukauloo A. Electrochemical Implication of a Hydrogen‐Bonded Imidazole on a Redox‐Active‐Bound Phenolate Group. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Sanae El Ghachtouli
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR‐CNRS 8182, Université de Paris‐Sud XI, 91405 Orsay, France, http://www.icmmo.u‐psud.fr/Labos/LCI/cv/aa.php
- Current address: Laboratoire Interface Matériaux Environnement, Faculté des Sciences Aïn Chock, Casablanca 20100, Maroc
| | - Benedikt Lassalle‐Kaiser
- CEA, iBiTec‐S, Service de Bioénergétique Biologie Structurale et Mécanismes (SB2SM), 91191 Gif‐sur‐Yvette, France
- Current address: Synchrotron SOLEIL, Saint‐Aubin, 91191 Gif‐sur‐Yvette, France
| | - Régis Guillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR‐CNRS 8182, Université de Paris‐Sud XI, 91405 Orsay, France, http://www.icmmo.u‐psud.fr/Labos/LCI/cv/aa.php
| | - Ally Aukauloo
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR‐CNRS 8182, Université de Paris‐Sud XI, 91405 Orsay, France, http://www.icmmo.u‐psud.fr/Labos/LCI/cv/aa.php
- CEA, iBiTec‐S, Service de Bioénergétique Biologie Structurale et Mécanismes (SB2SM), 91191 Gif‐sur‐Yvette, France
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28
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Šolc R, Gerzabek MH, Lischka H, Tunega D. Radical sites in humic acids: A theoretical study on protocatechuic and gallic acids. COMPUT THEOR CHEM 2014. [DOI: 10.1016/j.comptc.2014.01.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Megiatto Jr JD, Méndez-Hernández DD, Tejeda-Ferrari ME, Teillout AL, Llansola-Portolés MJ, Kodis G, Poluektov OG, Rajh T, Mujica V, Groy TL, Gust D, Moore TA, Moore AL. A bioinspired redox relay that mimics radical interactions of the Tyr–His pairs of photosystem II. Nat Chem 2014; 6:423-8. [DOI: 10.1038/nchem.1862] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 12/20/2013] [Indexed: 11/09/2022]
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Abstract
Proton-coupled electron transfer (PCET) plays a crucial role in many enzymatic reactions and is relevant for a variety of processes including water oxidation, nitrogen fixation, and carbon dioxide reduction. Much of the research on PCET has focused on transfers between molecules in their electronic ground states, but increasingly researchers are investigating PCET between photoexcited reactants. This Account describes recent studies of excited-state PCET with d(6) metal complexes emphasizing work performed in my laboratory. Upon photoexcitation, some complexes release an electron and a proton to benzoquinone reaction partners. Others act as combined electron-proton acceptors in the presence of phenols. As a result, we can investigate photoinduced PCET involving electron and proton transfer in a given direction, a process that resembles hydrogen-atom transfer (HAT). In other studies, the photoexcited metal complexes merely serve as electron donors or electron acceptors because the proton donating and accepting sites are located on other parts of the molecular PCET ensemble. We and others have used this multisite design to explore so-called bidirectional PCET which occurs in many enzymes. A central question in all of these studies is whether concerted proton-electron transfer (CPET) can compete kinetically with sequential electron and proton transfer steps. Short laser pulses can trigger excited-state PCET, making it possible to investigate rapid reactions. Luminescence spectroscopy is a convenient tool for monitoring PCET, but unambiguous identification of reaction products can require a combination of luminescence spectroscopy and transient absorption spectroscopy. Nevertheless, in some cases, distinguishing between PCET photoproducts and reaction products formed by simple photoinduced electron transfer (ET) (reactions that don't include proton transfer) is tricky. Some of the studies presented here deal directly with this important problem. In one case study we employed a cyclometalated iridium(III) complex. Our other studies with ruthenium(II) complexes and phenols focused on systematic variations of the reaction free energies for the CPET, ET, and proton transfer (PT) steps to explore their influence on the overall PCET reaction. Still other work with rhenium(I) complexes concentrated on the question of how the electronic structure of the metal-to-ligand charge transfer (MLCT) excited states affects PCET. We used covalent rhenium(I)-phenol dyads to explore the influence of the electron donor-electron acceptor distance on bidirectional PCET. In covalent triarylamine-Ru(bpy)₃²⁺/Os(bpy)₃²⁺-anthraquinone triads (bpy = 2,2'-bipyridine), hydrogen-bond donating solvents significantly lengthened the lifetimes of photogenerated electron/hole pairs because of hydrogen-bonding to the quinone radical anion. Until now, comparatively few researchers have investigated this variation of PCET: the strengthening of H-bonds upon photoreduction.
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Affiliation(s)
- Oliver S. Wenger
- Departement Chemie, Universität Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland
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Kuss-Petermann M, Wenger OS. Photoacid Behavior versus Proton-Coupled Electron Transfer in Phenol–Ru(bpy)32+ Dyads. J Phys Chem A 2013; 117:5726-33. [DOI: 10.1021/jp402567m] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Martin Kuss-Petermann
- Institut für Anorganische
Chemie, Georg-August-Universität Göttingen, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Oliver S. Wenger
- Departement für
Chemie, Universität Basel, Spitalstrasse 51, CH-4056 Basel, Switzerland
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Herzog W, Bronner C, Löffler S, He B, Kratzert D, Stalke D, Hauser A, Wenger OS. Electron Transfer between Hydrogen-Bonded Pyridylphenols and a Photoexcited Rhenium(I) Complex. Chemphyschem 2013; 14:1168-76. [DOI: 10.1002/cphc.201201069] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Indexed: 12/22/2022]
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33
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Kuss-Petermann M, Wolf H, Stalke D, Wenger OS. Influence of Donor–Acceptor Distance Variation on Photoinduced Electron and Proton Transfer in Rhenium(I)–Phenol Dyads. J Am Chem Soc 2012; 134:12844-54. [DOI: 10.1021/ja3053046] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Martin Kuss-Petermann
- Institut
für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstrasse
4, D-37077 Göttingen, Germany
| | - Hilke Wolf
- Institut
für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstrasse
4, D-37077 Göttingen, Germany
| | - Dietmar Stalke
- Institut
für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstrasse
4, D-37077 Göttingen, Germany
| | - Oliver S. Wenger
- Institut
für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstrasse
4, D-37077 Göttingen, Germany
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34
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Bronner C, Wenger OS. Proton-Coupled Electron Transfer between 4-Cyanophenol and Photoexcited Rhenium(I) Complexes with Different Protonatable Sites. Inorg Chem 2012; 51:8275-83. [DOI: 10.1021/ic300834c] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Catherine Bronner
- Georg-August-Universität, Institut für Anorganische Chemie, Tammannstrasse 4, D-37077
Göttingen, Germany
| | - Oliver S. Wenger
- Georg-August-Universität, Institut für Anorganische Chemie, Tammannstrasse 4, D-37077
Göttingen, Germany
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35
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Orio M, Jarjayes O, Baptiste B, Philouze C, Duboc C, Mathias JL, Benisvy L, Thomas F. Geometric and Electronic Structures of Phenoxyl Radicals Hydrogen Bonded to Neutral and Cationic Partners. Chemistry 2012; 18:5416-29. [DOI: 10.1002/chem.201102854] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Indexed: 11/06/2022]
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36
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Markle TF, Tenderholt AL, Mayer JM. Probing quantum and dynamic effects in concerted proton-electron transfer reactions of phenol-base compounds. J Phys Chem B 2012; 116:571-84. [PMID: 22148459 PMCID: PMC3974916 DOI: 10.1021/jp2091736] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The oxidation of three phenols, which contain an intramolecular hydrogen bond to a pendent pyridine or amine group, has been shown, in a previous experimental study, to undergo concerted proton-electron transfer (CPET). In this reaction, the electron is transferred to an outer-sphere oxidant, and the proton is transferred from the oxygen to nitrogen atom. In the present study, this reaction is studied computationally using a version of Hammes-Schiffer's multistate continuum theory where CPET is formulated as a transmission frequency between neutral and cation vibrational-electronic states. The neutral and cation proton vibrational wave functions are computed from one-dimensional potential energy surfaces (PESs) for the transferring proton in a fixed heavy atom framework. The overlap integrals for these neutral/cation wave functions, considering several initial (i.e., neutral) and final (i.e., cation) vibrational states, are used to evaluate the relative rates of oxidation. The analysis is extended to heavy atom configurations with various proton donor-acceptor (i.e., O-N) distances to assess the importance of heavy atom "gating". Such changes in d(ON) dramatically affect the nature of the proton PESs and wave functions. Surprisingly, the most reactive configurations have similar donor-acceptor distances despite the large (~0.2 Å) differences in the optimized structures. These theoretical results qualitatively reproduce the experimental faster reactivity of the reaction of the pyridyl derivative 1 versus the CH(2)-pyridyl 2, but the computed factor of 5 is smaller than the experimental 10(2). The amine derivative is calculated to react similarly to 1, which does not agree with the experiments, likely due to some of the simplifying assumptions made in applying the theory. The computed kinetic isotope effects (KIEs) and their temperature dependence are in agreement with experimental results.
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Affiliation(s)
| | - Adam L. Tenderholt
- Department of Chemistry, University of Washington, Box 351700 Seattle, WA 98195-1700
| | - James M. Mayer
- Department of Chemistry, University of Washington, Box 351700 Seattle, WA 98195-1700
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37
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Moore GF, Megiatto JD, Hambourger M, Gervaldo M, Kodis G, Moore TA, Gust D, Moore AL. Optical and electrochemical properties of hydrogen-bonded phenol-pyrrolidino[60]fullerenes. Photochem Photobiol Sci 2012; 11:1018-25. [DOI: 10.1039/c2pp05351a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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Zats GM, Arora H, Lavi R, Yufit D, Benisvy L. H-bonding and steric effects on the properties of phenolate and phenoxyl radical complexes of Cu(ii). Dalton Trans 2012; 41:47-9. [DOI: 10.1039/c1dt11868d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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39
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Amorati R, Pedulli GF. Hydrogen bond donating ability of meta and parahydroxy phenoxyl radicals. Org Biomol Chem 2012; 10:814-8. [DOI: 10.1039/c1ob06502e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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40
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Martínez-Rivera MC, Berry BW, Valentine KG, Westerlund K, Hay S, Tommos C. Electrochemical and structural properties of a protein system designed to generate tyrosine Pourbaix diagrams. J Am Chem Soc 2011; 133:17786-95. [PMID: 22011192 DOI: 10.1021/ja206876h] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This report describes a model protein specifically tailored to electrochemically study the reduction potential of protein tyrosine radicals as a function of pH. The model system is based on the 67-residue α(3)Y three-helix bundle. α(3)Y contains a single buried tyrosine at position 32 and displays structural properties inherent to a protein. The present report presents differential pulse voltammograms obtained from α(3)Y at both acidic (pH 5.6) and alkaline (pH 8.3) conditions. The observed Faradaic response is uniquely associated with Y32, as shown by site-directed mutagenesis. This is the first time voltammetry is successfully applied to detect a redox-active tyrosine residing in a structured protein environment. Tyrosine is a proton-coupled electron-transfer cofactor making voltammetry-based pH titrations a central experimental approach. A second set of experiments was performed to demonstrate that pH-dependent studies can be conducted on the redox-active tyrosine without introducing large-scale structural changes in the protein scaffold. α(3)Y was re-engineered with the specific aim to place the imidazole group of a histidine close to the Y32 phenol ring. α(3)Y-K29H and α(3)Y-K36H each contain a histidine residue whose protonation perturbs the fluorescence of Y32. We show that these variants are stable and well-folded proteins whose helical content, tertiary structure, solution aggregation state, and solvent-sequestered position of Y32 remain pH insensitive across a range of at least 3-4 pH units. These results confirm that the local environment of Y32 can be altered and the resulting radical site studied by voltammetry over a broad pH range without interference from long-range structural effects.
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Affiliation(s)
- Melissa C Martínez-Rivera
- Graduate Group in Biochemistry & Molecular Biophysics and Department of Biochemistry & Biophysics, 905 Stellar-Chance Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059, United States
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41
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Wanke R, Benisvy L, Kuznetsov ML, Guedes da Silva MFC, Pombeiro AJL. Persistent Hydrogen-Bonded and Non-Hydrogen-Bonded Phenoxyl Radicals. Chemistry 2011; 17:11882-92. [DOI: 10.1002/chem.201101509] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Indexed: 11/10/2022]
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42
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Matsuoka H, Shen JR, Kawamori A, Nishiyama K, Ohba Y, Yamauchi S. Proton-Coupled Electron-Transfer Processes in Photosystem II Probed by Highly Resolved g-Anisotropy of Redox-Active Tyrosine YZ. J Am Chem Soc 2011; 133:4655-60. [DOI: 10.1021/ja2000566] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hideto Matsuoka
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira-2-1-1, Aobaku, Sendai 980-8577, Japan
| | - Jian-Ren Shen
- Graduate School of Natural Science and Technology, Department of Biology, Faculty of Science, Okayama University, Naka-Tsushima, Okayama 700-8530, Japan
| | - Asako Kawamori
- Agape-Kabutoyama Institute of Medicine, Kabutoyama-cho 54-3, Nishinomiya 662-0001, Japan
| | - Kei Nishiyama
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira-2-1-1, Aobaku, Sendai 980-8577, Japan
| | - Yasunori Ohba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira-2-1-1, Aobaku, Sendai 980-8577, Japan
| | - Seigo Yamauchi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira-2-1-1, Aobaku, Sendai 980-8577, Japan
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43
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Zats GM, Arora H, Lavi R, Yufit D, Benisvy L. Phenolate and phenoxyl radical complexes of Cu(ii) and Co(iii), bearing a new redox active N,O-phenol-pyrazole ligand. Dalton Trans 2011; 40:10889-96. [DOI: 10.1039/c1dt10615e] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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44
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Stoll S, Ozarowski A, Britt RD, Angerhofer A. Atomic hydrogen as high-precision field standard for high-field EPR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 207:158-63. [PMID: 20813570 PMCID: PMC2956851 DOI: 10.1016/j.jmr.2010.08.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 06/08/2010] [Accepted: 08/06/2010] [Indexed: 05/05/2023]
Abstract
We introduce atomic hydrogen trapped in an octaisobutylsilsesquioxane nanocage (H@iBuT₈) as a new molecular high-precision magnetic field standard for high-field EPR spectroscopy of organic radicals and other systems with signals around g=2. Its solid-state EPR spectrum consists of two 0.2 mT wide lines separated by about 51 mT and centered at g≈2. The isotropic g factor is 2.00294(3) and essentially temperature independent. The isotropic ¹H hyperfine coupling constant is 1416.8(2) MHz below 70 K and decreases slightly with increasing temperature to 1413.7(1) MHz at room temperature. The spectrum of the standard does not overlap with those of most organic radicals, and it can be easily prepared and is stable at room temperature.
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Affiliation(s)
- Stefan Stoll
- Department of Chemistry, University of California, One Shields Ave, Davis, California 95616, USA
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, USA
| | - R. David Britt
- Department of Chemistry, University of California, One Shields Ave, Davis, California 95616, USA
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45
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Cotton FA, Chiarella GM, Dalal NS, Murillo CA, Wang Z, Young MD. Proof by EPR Spectroscopy that the Unpaired Electron in an Os27+ Species Is in a δ* Metal-based Molecular Orbital. Inorg Chem 2009; 49:319-24. [DOI: 10.1021/ic902087e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Gina M. Chiarella
- Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, Texas 77842-3012 and
| | - Naresh S. Dalal
- Department of Chemistry, Dittmer Building, Florida State University, Tallahassee, Florida, 32306-4390
| | - Carlos A. Murillo
- Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, Texas 77842-3012 and
| | - Zhenxing Wang
- Department of Chemistry, Dittmer Building, Florida State University, Tallahassee, Florida, 32306-4390
| | - Mark D. Young
- Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, Texas 77842-3012 and
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46
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Jenson DL, Barry BA. Proton-coupled electron transfer in photosystem II: proton inventory of a redox active tyrosine. J Am Chem Soc 2009; 131:10567-73. [PMID: 19586025 PMCID: PMC2846377 DOI: 10.1021/ja902896e] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photosystem II (PSII) catalyzes the light driven oxidation of water and the reduction of plastoquinone. PSII is a multisubunit membrane protein; the D1 and D2 polypeptides form the heterodimeric core of the PSII complex. Water oxidation occurs at a manganese-containing oxygen evolving complex (OEC). PSII contains two redox active tyrosines, Y(Z) and Y(D), which form the neutral tyrosyl radicals, Y(z)(*) and Y(D)(*). Y(D) has been assigned as tyrosine 160 in the D2 polypeptide through isotopic labeling and site-directed mutagenesis. Whereas Y(D) is not directly involved in the oxidation of water, it has been implicated in the formation and stabilization of the OEC. PSII structures have shown Y(D) to be within hydrogen-bonding distance of histidine 189 in the D2 polypeptide. Spectroscopic studies have suggested that a proton is transferred between Y(D) and histidine 189 when Y(D) is oxidized and reduced. In our previous work, we used (2)H(2)O solvent exchange to demonstrate that the mechanism of Y(D) proton-coupled electron transfer (PCET) differs at high and low pH. In this article, we utilize the proton inventory technique to obtain more information concerning PCET mechanism at high pH. The hypercurvature of the proton inventory data provides evidence for the existence of multiple, proton-donation pathways to Y(D)(*). In addition, at least one of these pathways must involve the transfer of more than one proton.
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Affiliation(s)
- David L. Jenson
- School of Chemistry and Biochemistry and the Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Bridgette A. Barry
- School of Chemistry and Biochemistry and the Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
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47
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Yang S, Cai W, Yang J, Zeng H. General and simple route to micro/nanostructured hollow-sphere arrays based on electrophoresis of colloids induced by laser ablation in liquid. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:8287-8291. [PMID: 19425560 DOI: 10.1021/la900496p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A general and simple route was presented to fabricate hollow sphere arrays (HSAs) with hierarchical micro/nanostructure based on electrophoresis on a polystyrene colloidal monolayer in a corresponding colloidal solution prepared by laser ablation in liquid. Si was chosen as a model material to demonstrate the validity of the route. The size and structure of such-prepared hollow spheres can be easily controlled by the size of the polystyrene spheres, the electrophoresis parameters, and the morphology of the colloidal nanoparticles. Further experiments have revealed that this strategy can be extended to produce other semiconductors' and metals' compact or noncompact HSAs, and even multicomponent HSAs with controllable spacings between adjacent spheres and tunable size of nanoparticles in the shell layers. This study could be important to synthesize some key materials in the fields of ion batteries, surface enhanced Raman scattering, new micro/nanostructured devices, and so on.
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Affiliation(s)
- Shikuan Yang
- Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
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48
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Gauss J, Kállay M, Neese F. Calculation of Electronic g-Tensors using Coupled Cluster Theory. J Phys Chem A 2009; 113:11541-9. [DOI: 10.1021/jp9028535] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Jürgen Gauss
- Institut für Physikalische Chemie, Universität Mainz, D-55099 Mainz, Germany, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, P.O. Box 91, H-1521 Budapest, Hungary, and Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstrasse 12, D-53115 Bonn, Germany
| | - Mihály Kállay
- Institut für Physikalische Chemie, Universität Mainz, D-55099 Mainz, Germany, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, P.O. Box 91, H-1521 Budapest, Hungary, and Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstrasse 12, D-53115 Bonn, Germany
| | - Frank Neese
- Institut für Physikalische Chemie, Universität Mainz, D-55099 Mainz, Germany, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, P.O. Box 91, H-1521 Budapest, Hungary, and Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstrasse 12, D-53115 Bonn, Germany
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49
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Roy N, Sproules S, Bothe E, Weyhermüller T, Wieghardt K. Polynuclear Complexes Containing the Redox Noninnocent Schiff Base Ligand 2-[(E)-2-Mercaptophenylimino]methyl-4,6-di-tert-butylphenolate(2-). Eur J Inorg Chem 2009. [DOI: 10.1002/ejic.200900168] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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50
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Stoll S, Gunn A, Brynda M, Sughrue W, Kohler AC, Ozarowski A, Fisher AJ, Lagarias JC, Britt RD. Structure of the biliverdin radical intermediate in phycocyanobilin:ferredoxin oxidoreductase identified by high-field EPR and DFT. J Am Chem Soc 2009; 131:1986-95. [PMID: 19159240 DOI: 10.1021/ja808573f] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cyanobacterial enzyme phycocyanobilin:ferredoxin oxidoreductase (PcyA) catalyzes the two-step four-electron reduction of biliverdin IXalpha to phycocyanobilin, the precursor of biliprotein chromophores found in phycobilisomes. It is known that catalysis proceeds via paramagnetic radical intermediates, but the structure of these intermediates and the transfer pathways for the four protons involved are not known. In this study, high-field electron paramagnetic resonance (EPR) spectroscopy of frozen solutions and single crystals of the one-electron reduced protein-substrate complex of two PcyA mutants D105N from the cyanobacteria Synechocystis sp. PCC6803 and Nostoc sp. PCC7120 are examined. Detailed analysis of Synechocystis D105N mutant spectra at 130 and 406 GHz reveals a biliverdin radical with a very narrow g tensor with principal values 2.00359(5), 2.00341(5), and 2.00218(5). Using density-functional theory (DFT) computations to explore the possible protonation states of the biliverdin radical, it is shown that this g tensor is consistent with a biliverdin radical where the carbonyl oxygen atoms on both the A and the D pyrrole rings are protonated. This experimentally confirms the reaction mechanism recently proposed (Tu, et al. Biochemistry 2007, 46, 1484).
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Affiliation(s)
- Stefan Stoll
- Department of Chemistry, University of California Davis, 1 Shields Avenue, Davis, California 95616, USA
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