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Thioester synthesis by a designed nickel enzyme models prebiotic energy conversion. Proc Natl Acad Sci U S A 2022; 119:e2123022119. [PMID: 35858422 PMCID: PMC9335327 DOI: 10.1073/pnas.2123022119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The formation of carbon-carbon bonds from prebiotic precursors such as carbon dioxide represents the foundation of all primordial life processes. In extant organisms, this reaction is carried out by the carbon monoxide dehydrogenase (CODH)/acetyl coenzyme A synthase (ACS) enzyme, which performs the cornerstone reaction in the ancient Wood-Ljungdahl metabolic pathway to synthesize the key biological metabolite, acetyl-CoA. Despite its significance, a fundamental understanding of this transformation is lacking, hampering efforts to harness analogous chemistry. To address these knowledge gaps, we have designed an artificial metalloenzyme within the azurin protein scaffold as a structural, functional, and mechanistic model of ACS. We demonstrate the intermediacy of the NiI species and requirement for ordered substrate binding in the bioorganometallic carbon-carbon bond-forming reaction from the one-carbon ACS substrates. The electronic and geometric structures of the nickel-acetyl intermediate have been characterized using time-resolved optical, electron paramagnetic resonance, and X-ray absorption spectroscopy in conjunction with quantum chemical calculations. Moreover, we demonstrate that the nickel-acetyl species is chemically competent for selective acyl transfer upon thiol addition to biosynthesize an activated thioester. Drawing an analogy to the native enzyme, a mechanism for thioester generation by this ACS model has been proposed. The fundamental insight into the enzymatic process provided by this rudimentary ACS model has implications for the evolution of primitive ACS-like proteins. Ultimately, these findings offer strategies for development of highly active catalysts for sustainable generation of liquid fuels from one-carbon substrates, with potential for broad applications across diverse fields ranging from energy storage to environmental remediation.
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Cutsail III GE, DeBeer S. Challenges and Opportunities for Applications of Advanced X-ray Spectroscopy in Catalysis Research. ACS Catal 2022. [DOI: 10.1021/acscatal.2c01016] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- George E. Cutsail III
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstr. 5-7, 45117 Essen, Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
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Geoghegan BL, Liu Y, Peredkov S, Dechert S, Meyer F, DeBeer S, Cutsail GE. Combining Valence-to-Core X-ray Emission and Cu K-edge X-ray Absorption Spectroscopies to Experimentally Assess Oxidation State in Organometallic Cu(I)/(II)/(III) Complexes. J Am Chem Soc 2022; 144:2520-2534. [PMID: 35050605 PMCID: PMC8855422 DOI: 10.1021/jacs.1c09505] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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A series of organometallic
copper complexes in formal oxidation
states ranging from +1 to +3 have been characterized by a combination
of Cu K-edge X-ray absorption (XAS) and Cu Kβ valence-to-core
X-ray emission spectroscopies (VtC XES). Each formal oxidation state
exhibits distinctly different XAS and VtC XES transition energies
due to the differences in the Cu Zeff, concomitant with
changes in physical oxidation state from +1 to +2 to +3. Herein, we
demonstrate the sensitivity of XAS and VtC XES to the physical oxidation
states of a series of N-heterocyclic carbene (NHC) ligated organocopper
complexes. We then extend these methods to the study of the [Cu(CF3)4]− ion. Complemented by computational
methods, the observed spectral transitions are correlated with the
electronic structure of the complexes and the Cu Zeff.
These calculations demonstrate that a contraction of the Cu 1s orbitals
to deeper binding energy upon oxidation of the Cu center manifests
spectroscopically as a stepped increase in the energy of both XAS
and Kβ2,5 emission features with increasing formal
oxidation state within the [Cun+(NHC2)]n+ series. The newly synthesized Cu(III) cation
[CuIII(NHC4)]3+ exhibits spectroscopic
features and an electronic structure remarkably similar to [Cu(CF3)4]−, supporting a physical oxidation
state assignment of low-spin d8 Cu(III) for [Cu(CF3)4]−. Combining XAS and VtC XES
further demonstrates the necessity of combining multiple spectroscopies
when investigating the electronic structures of highly covalent copper
complexes, providing a template for future investigations into both
synthetic and biological metal centers.
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Affiliation(s)
- Blaise L. Geoghegan
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstrasse 5-7, 45117 Essen, Germany
| | - Yang Liu
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Sergey Peredkov
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Sebastian Dechert
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Franc Meyer
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - George E. Cutsail
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstrasse 5-7, 45117 Essen, Germany
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Yang J, Dong HT, Seo MS, Larson VA, Lee YM, Shearer J, Lehnert N, Nam W. The Oxo-Wall Remains Intact: A Tetrahedrally Distorted Co(IV)-Oxo Complex. J Am Chem Soc 2021; 143:16943-16959. [PMID: 34609879 DOI: 10.1021/jacs.1c04919] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In this paper, we report the preparation, spectroscopic and theoretical characterization, and reactivity studies of a Co(IV)-oxo complex bearing an N4-macrocyclic coligand, 12-TBC (12-TBC = 1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane). On the basis of the ligand and the structure of the Co(II) precursor, [CoII(12-TBC)(CF3SO3)2], one would assume that this species corresponds to a tetragonal Co(IV)-oxo complex, but the spectroscopic data do not support this notion. Co K-edge XAS data show that the treatment of the Co(II) precursor with iodosylbenzene (PhIO) as an oxidant at -40 °C in the presence of a proton source leads to a distinct shift in the Co K-edge, in agreement with the formation of a Co(IV) intermediate. The presence of the oxo group is further demonstrated by resonance Raman (rRaman) spectroscopy. Interestingly, the EPR data of this complex show a high degree of rhombicity, indicating structural distortion. This is further supported by the EXAFS data. Using DFT calculations, a structural model is developed for this complex with a ligand-protonated structure that features a Co═O···HN hydrogen bond and a four-coordinate Co center in a seesaw-shaped coordination geometry. Magnetic circular dichroism (MCD) spectroscopy further supports this finding. The hydrogen bond leads to an interesting polarization of the Co-oxo π-bonds, where one O(p) lone-pair is stabilized and leads to a regular Co(d) interaction, whereas the other π-bond shows an inverted ligand field. The reactivity of this complex in hydrogen atom and oxygen atom transfer reactions is discussed as well.
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Affiliation(s)
- Jindou Yang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Hai T Dong
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Virginia A Larson
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Jason Shearer
- Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, United States
| | - Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea.,School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, China
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Zsombor-Pindera J, Effaty F, Escomel L, Patrick B, Kennepohl P, Ottenwaelder X. Five Nitrogen Oxidation States from Nitro to Amine: Stabilization and Reactivity of a Metastable Arylhydroxylamine Complex. J Am Chem Soc 2020; 142:19023-19028. [PMID: 33124796 DOI: 10.1021/jacs.0c09300] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Redox noninnocent ligands enhance the reactivity of the metal they complex, a strategy used by metalloenzymes and in catalysis. Herein, we report a series of copper complexes with the same ligand framework, but with a pendant nitrogen group that spans five different redox states between nitro and amine. Of particular interest is the synthesis of a unprecedented copper(I)-arylhydroxylamine complex. While hydroxylamines typically disproportionate or decompose in the presence of transition metal ions, the reactivity of this metastable species is arrested by the presence of an intramolecular hydrogen bond. Two-electron oxidation yields a copper(II)-(arylnitrosyl radical) complex that can dissociate to a copper(I) species with uncoordinated arylnitroso. This combination of ligand redox noninnocence and hemilability provides opportunities in catalysis for two-electron chemistry via a one-electron copper(I/II) shuttle, as exemplified with an aerobic alcohol oxidation.
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Affiliation(s)
- Joseph Zsombor-Pindera
- Department of Chemistry and Biochemistry, Concordia University, Montreal, QC H4B 1R6, Canada.,Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Farshid Effaty
- Department of Chemistry and Biochemistry, Concordia University, Montreal, QC H4B 1R6, Canada
| | - Léon Escomel
- Department of Chemistry and Biochemistry, Concordia University, Montreal, QC H4B 1R6, Canada
| | - Brian Patrick
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Pierre Kennepohl
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Xavier Ottenwaelder
- Department of Chemistry and Biochemistry, Concordia University, Montreal, QC H4B 1R6, Canada
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