1
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Dutra FR, Vasiliu M, Gomez AN, Xia D, Dixon DA. Prediction of Redox Potentials for U, Np, Pu, and Am in Aqueous Solution. J Phys Chem A 2024; 128:5612-5626. [PMID: 38959054 DOI: 10.1021/acs.jpca.4c02902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
The redox properties of the actinides in aqueous solution are important for fuel production/reprocessing and understanding the environmental impact of nuclear waste. The redox potentials for U, Np, Pu, and Am in oxidation states from 0 up to VII (as appropriate) in aqueous solutions have been predicted at the density functional theory level with the B3LYP functional, Stuttgart small core pseudopotential basis sets for the actinides, and explicit (30H2O molecules)/implicit treatment of the aqueous solvent using the self-consistent reaction field COSMO and SMD approaches for the implicit solvation. The predictions of the structural parameters of clusters incorporating first and second solvation shells are consistent with the available experimental data. Our results are typically within 0.2 V of the available experimental data using two explicit solvation shells with an implicit solvent model. The use of the PW91 functional substantially improved the prediction of the Pu(VI/V) redox couple. The redox couples for An(VI/IV) and An(V/IV) which involve the addition of protons and removal of the actinyl oxygens led to slightly larger differences from an experiment. The An(IV/0) and An(III/0) couples were reliably predicted with our approach. Predictions of the unknown An(II/I) redox potentials were negative, consistent with expectations, and predictions for unknown An(VII/VI), An(III/II), and An(II/0) redox couples improve prior estimates.
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Affiliation(s)
- Felipe R Dutra
- Instituto de Química, Universidade Estadual de Campinas, Barão Geraldo, P.O. Box 6154, Campinas 13083-970, São Paulo, Brazil
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - Monica Vasiliu
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - Amber N Gomez
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - Donna Xia
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - David A Dixon
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
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2
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Ould Mohamed L, Abtouche S, Ghoualem Z, Assfeld X. Unraveling redox pathways of the disulfide bond in dimethyl disulfide: Ab initio modeling. J Mol Model 2024; 30:180. [PMID: 38780881 DOI: 10.1007/s00894-024-05963-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 05/03/2024] [Indexed: 05/25/2024]
Abstract
CONTEXT In cellular environments, the reduction of disulfide bonds is pivotal for protein folding and synthesis. However, the intricate enzymatic mechanisms governing this process remain poorly understood. This study addresses this gap by investigating a disulfide bridge reduction reaction, serving as a model for comprehending electron and proton transfer in biological systems. Six potential mechanisms for reducing the dimethyl disulfide (DMDS) bridge through electron and proton capture were explored. Thermodynamic and kinetic analyses elucidated the sequence of proton and electron addition. MD-PMM, a method that combines molecular dynamics simulations and quantum-chemical calculations, was employed to compute the redox potential of the mechanism. This research provides valuable insights into the mechanisms and redox potentials involved in disulfide bridge reduction within proteins, offering an understanding of phenomena that are challenging to explore experimentally. METHODS All calculations used the Gaussian 09 software package at the MP2/6-311 + g(d,p) theory level. Visualization of the molecular orbitals and electron densities was conducted using Gaussview6. Molecular dynamics simulations were performed using GROMACS with the CHARMM36 force field. The PyMM program (Python Program for QM/MM Simulations Based on the Perturbed Matrix Method) is used to apply the Perturbed Matrix Method to MD simulations.
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Affiliation(s)
- Lina Ould Mohamed
- Laboratoire de Physico Chimie Théorique Et Chimie Informatique, LPCTCI, Faculté de Chimie, USTHB, 16111, Algiers, Algeria
| | - Soraya Abtouche
- Laboratoire de Physico Chimie Théorique Et Chimie Informatique, LPCTCI, Faculté de Chimie, USTHB, 16111, Algiers, Algeria.
| | - Zeyneb Ghoualem
- Laboratoire de Physico Chimie Théorique Et Chimie Informatique, LPCTCI, Faculté de Chimie, USTHB, 16111, Algiers, Algeria
| | - Xavier Assfeld
- Physique et Chimie Théoriques, UMR 7019, Faculté des Sciences et Technologies, Université de Lorraine, BP 70239, 54506, Vandoeuvre Lès Nancy Cedex, France
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3
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Zhang SY, Tang SB, Jiang YX, Zhu RY, Wang ZX, Long B, Su J. Mechanism of the Visible-Light-Promoted C(sp 3)-H Oxidation via Uranyl Photocatalysis. Inorg Chem 2024; 63:2418-2430. [PMID: 38264973 DOI: 10.1021/acs.inorgchem.3c03347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Uranyl cation, as an emerging photocatalyst, has been successfully applied to synthetic chemistry in recent years and displayed remarkable catalytic ability under visible light. However, the molecular-level reaction mechanisms of uranyl photocatalysis are unclear. Here, we explore the mechanism of the stepwise benzylic C-H oxygenation of typical alkyl-substituted aromatics (i.e., toluene, ethylbenzene, and cumene) via uranyl photocatalysis using theoretical and experimental methods. Theoretical calculation results show that the most favorable reaction path for uranyl photocatalytic oxidation is as follows: first, hydrogen atom transfer (HAT) from the benzyl position to form a carbon radical ([R•]), then oxygen addition ([R•] + O2 → [ROO•]), then radical-radical combination ([ROO•] + [R•] → [ROOR] → 2[RO•]), and eventually [RO•] reduction to produce alcohols, of which 2° alcohol would further be oxidized to ketones and 1° would be stepwise-oxygenated to acids. The results of the designed verification experiments and the capture of reactive intermediates were consistent with those of theoretical calculations and the previously reported research that the active benzylic C-H would be stepwise-oxygenated in the presence of uranyl. This work deepens our understanding of the HAT mechanism of uranyl photocatalysis and provides important theoretical support for the relevant application of uranyl photocatalysts in organic transformation.
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Affiliation(s)
- Shu-Yun Zhang
- College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
| | - Song-Bai Tang
- College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
| | - Yan-Xin Jiang
- College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
| | - Ru-Yu Zhu
- College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
| | - Zi-Xin Wang
- College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
| | - Bo Long
- College of Materials Science and Engineering, Guizhou Minzu University, Guiyang 550025, P. R. China
| | - Jing Su
- College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
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4
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Jafari S, Ryde U, Irani M. Two local minima for structures of [4Fe-4S] clusters obtained with density functional theory methods. Sci Rep 2023; 13:10832. [PMID: 37402767 PMCID: PMC10319735 DOI: 10.1038/s41598-023-37755-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 06/27/2023] [Indexed: 07/06/2023] Open
Abstract
[4Fe-4S] clusters are essential cofactors in many proteins involved in biological redox-active processes. Density functional theory (DFT) methods are widely used to study these clusters. Previous investigations have indicated that there exist two local minima for these clusters in proteins. We perform a detailed study of these minima in five proteins and two oxidation states, using combined quantum mechanical and molecular mechanical (QM/MM) methods. We show that one local minimum (L state) has longer Fe-Fe distances than the other (S state), and that the L state is more stable for all cases studied. We also show that some DFT methods may only obtain the L state, while others may obtain both states. Our work provides new insights into the structural diversity and stability of [4Fe-4S] clusters in proteins, and highlights the importance of reliable DFT methods and geometry optimization. We recommend r2SCAN for optimizing [4Fe-4S] clusters in proteins, which gives the most accurate structures for the five proteins studied.
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Affiliation(s)
- Sonia Jafari
- Department of Chemistry, University of Kurdistan, P.O.Box 66175-416, Sanandaj, Iran
| | - Ulf Ryde
- Department of Theoretical Chemistry, Lund University, P.O.Box 124, 221 00, Lund, Sweden
| | - Mehdi Irani
- Department of Chemistry, University of Kurdistan, P.O.Box 66175-416, Sanandaj, Iran.
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5
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Tamulienė J, Valiauga B, Čėnas N. Modified quantum mechanical approach for the estimation of single-electron reduction potential of nitroaromatic compounds in aqueous medium. Free Radic Res 2023:1-8. [PMID: 37171206 DOI: 10.1080/10715762.2023.2213821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The midpoint single-electron reduction potential of nitroaromatic compounds in aqueous medium at pH 7.0 (potential of ArNO2/ArNO2·- couple, Em7) frequently determines their therapeutic and/or toxic properties. However, its estimation remains a complex problem. We propose a modified method of Em7 estimation by quantum mechanical calculations, based on the use of the dielectric continuum model together with a certain number of H2O molecules at the vicinity of nitro group. The optimal number of H2O molecules corresponds to a minimal difference between the experimentally determined and calculated values of Em7, and/or the most negative value of calculated Em7. This enabled us to calculate the Em7 values for a number of ArNO2 (n = 19) with the average deviation of 0.027 V from the experimentally determined ones. Apart from nitrobenzene derivatives, the application of this approach for the representatives of nitropyridines, nitrofurans, nitrothiophenes, and nitrothiazoles was demonstrated. In this case, nitroimidazole derivatives are an exception, evidently due to a strong proton accepting properties of N3 atom of their free radicals.
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Affiliation(s)
- Jelena Tamulienė
- Vilnius University, Faculty of Physics, Institute of Theoretical Physics and Astronomy, Vilnius, Lithuania
| | | | - Narimantas Čėnas
- Institute of Biochemistry of Vilnius University, Vilnius, Lithuania
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6
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de la Cruz C, Sanz R, Suárez A, Ventosa E, Marcilla R, Mavrandonakis A. A Systematic Study on the Redox Potentials of Phenazine-Derivatives in Aqueous Media: A Combined Computational and Experimental Work. CHEMSUSCHEM 2023; 16:e202201984. [PMID: 36753400 DOI: 10.1002/cssc.202201984] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/30/2023] [Indexed: 06/18/2023]
Abstract
Phenazines are an emerging class of organic compounds that have been recently utilized in aqueous redox flow batteries, a promising technology for large-scale energy storage. A virtual screening based on density functional theory calculations is used to investigate the redox potentials of around 100 phenazine derivatives in aqueous media containing various electron-donating or electron-withdrawing groups at different positions. The calculations identify the crucial positions that should be functionalized with multiple hydroxy groups to design new anolytes. The combined experimental-computational methodology reported herein guides the development of a new molecule with a record low reversible redox potential as a potential anolyte for aqueous redox flow batteries.
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Affiliation(s)
- Carlos de la Cruz
- Electrochemical Processes Unit, IMDEA Energy, Avenida Ramón de la Sagra 3, 28935, Móstoles, Spain
| | - Roberto Sanz
- Department of Chemistry, University of Burgos, Pza. Misael Bañuelos s/n, Burgos, E-09001, Spain
| | - Anisley Suárez
- Department of Chemistry, University of Burgos, Pza. Misael Bañuelos s/n, Burgos, E-09001, Spain
| | - Edgar Ventosa
- Department of Chemistry, University of Burgos, Pza. Misael Bañuelos s/n, Burgos, E-09001, Spain
| | - Rebeca Marcilla
- Electrochemical Processes Unit, IMDEA Energy, Avenida Ramón de la Sagra 3, 28935, Móstoles, Spain
| | - Andreas Mavrandonakis
- Electrochemical Processes Unit, IMDEA Energy, Avenida Ramón de la Sagra 3, 28935, Móstoles, Spain
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7
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Ramos DR, Furtmüller PG, Obinger C, Peña-Gallego Á, Pérez-Juste I, Santaballa JA. Common Reactivity and Properties of Heme Peroxidases: A DFT Study of Their Origin. Antioxidants (Basel) 2023; 12:antiox12020303. [PMID: 36829861 PMCID: PMC9952403 DOI: 10.3390/antiox12020303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/06/2023] [Accepted: 01/25/2023] [Indexed: 01/31/2023] Open
Abstract
Electronic structure calculations using the density-functional theory (DFT) have been performed to analyse the effect of water molecules and protonation on the heme group of peroxidases in different redox (ferric, ferrous, compounds I and II) and spin states. Shared geometries, spectroscopic properties at the Soret region, and the thermodynamics of peroxidases are discussed. B3LYP and M06-2X density functionals with different basis sets were employed on a common molecular model of the active site (Fe-centred porphine and proximal imidazole). Computed Gibbs free energies indicate that the corresponding aquo complexes are not thermodynamically stable, supporting the five-coordinate Fe(III) centre in native ferric peroxidases, with a water molecule located at a non-bonding distance. Protonation of the ferryl oxygen of compound II is discussed in terms of thermodynamics, Fe-O bond distances, and redox properties. It is demonstrated that this protonation is necessary to account for the experimental data, and computed Gibbs free energies reveal pKa values of compound II about 8.5-9.0. Computation indicates that the general oxidative properties of peroxidase intermediates, as well as their reactivity towards water and protons and Soret bands, are mainly controlled by the iron porphyrin and its proximal histidine ligand.
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Affiliation(s)
- Daniel R. Ramos
- Chemical Reactivity & Photoreactivity Group (React!), Department of Chemistry, CICA & Faculty of Sciences, Universidade da Coruña, Campus da Zapateira, E-15071 A Coruña, Spain
- Departamento de Química Física, Universidade de Vigo, Campus Universitario Lagoas-Marcosende, E-36310 Vigo, Spain
- Correspondence: (D.R.R.); (J.A.S.)
| | - Paul G. Furtmüller
- Institute of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Christian Obinger
- Institute of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Ángeles Peña-Gallego
- Departamento de Química Física, Universidade de Vigo, Campus Universitario Lagoas-Marcosende, E-36310 Vigo, Spain
| | - Ignacio Pérez-Juste
- Departamento de Química Física, Universidade de Vigo, Campus Universitario Lagoas-Marcosende, E-36310 Vigo, Spain
| | - J. Arturo Santaballa
- Chemical Reactivity & Photoreactivity Group (React!), Department of Chemistry, CICA & Faculty of Sciences, Universidade da Coruña, Campus da Zapateira, E-15071 A Coruña, Spain
- Correspondence: (D.R.R.); (J.A.S.)
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8
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Jafari S, Tavares Santos YA, Bergmann J, Irani M, Ryde U. Benchmark Study of Redox Potential Calculations for Iron-Sulfur Clusters in Proteins. Inorg Chem 2022; 61:5991-6007. [PMID: 35403427 PMCID: PMC9044450 DOI: 10.1021/acs.inorgchem.1c03422] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Redox potentials
have been calculated for 12 different iron–sulfur
sites of 6 different types with 1–4 iron ions. Structures were
optimized with combined quantum mechanical and molecular mechanical
(QM/MM) methods, and the redox potentials were calculated using the
QM/MM energies, single-point QM methods in a continuum solvent or
by QM/MM thermodynamic cycle perturbations. We show that the best
results are obtained with a large QM system (∼300 atoms, but
a smaller QM system, ∼150 atoms, can be used for the QM/MM
geometry optimization) and a large value of the dielectric constant
(80). For absolute redox potentials, the B3LYP density functional
method gives better results than TPSS, and the results are improved
with a larger basis set. However, for relative redox potentials, the
opposite is true. The results are insensitive to the force field (charges
of the surroundings) used for the QM/MM calculations or whether the
protein and solvent outside the QM system are relaxed or kept fixed
at the crystal structure. With the best approach for relative potentials,
mean absolute and maximum deviations of 0.17 and 0.44 V, respectively,
are obtained after removing a systematic error of −0.55 V.
Such an approach can be used to identify the correct oxidation states
involved in a certain redox reaction. We
have studied redox potentials of 12 iron−sulfur
sites of 6 types with 1−4 iron ions. Structures were optimized
with combined quantum mechanical and molecular mechanical (QM/MM)
methods, and the redox potentials were calculated with QM/MM, QM calculations
in a continuum solvent or by QM/MM thermodynamic cycle perturbations.
The best results are obtained with the second approach using ∼300
atoms in the QM model and a large dielectric constant.
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Affiliation(s)
- Sonia Jafari
- Department of Chemistry, University of Kurdistan, 66175-416 Sanandaj, Iran.,Department of Theoretical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Yakini A Tavares Santos
- Department of Theoretical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Justin Bergmann
- Department of Theoretical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Mehdi Irani
- Department of Chemistry, University of Kurdistan, 66175-416 Sanandaj, Iran
| | - Ulf Ryde
- Department of Theoretical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
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9
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Orjuela AL, Núñez-Zarur F, Alí-Torres J. A computational protocol for the calculation of the standard reduction potential of iron complexes: application to Fe 2+/3+-Aβ model systems relevant to Alzheimer's disease. RSC Adv 2022; 12:24077-24087. [PMID: 36200023 PMCID: PMC9451132 DOI: 10.1039/d2ra03907a] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/17/2022] [Indexed: 11/22/2022] Open
Abstract
Iron complexes play a key role in several biological processes, and they are also related to the development of neurological disorders, such as Alzheimer's and Parkinson's diseases. One of the main properties involved in these processes is the standard reduction potential (SRP) of iron complexes. However, the calculation of this property is challenging, mainly due to problems in the electronic structure description, solvent effects and the thermodynamic cycles used for its calculation. In this work, we proposed a computational protocol for the calculation of SRPs of iron complexes by evaluating a wide range of density functionals for the electronic structure description, two implicit solvent models with varying radii and two thermodynamic cycles. Results show that the M06L density functional in combination with the SMD solvation model and the isodesmic method provides good results compared with SRP experimental values for a set of iron complexes. Finally, this protocol was applied to three Fe2+/3+-Aβ model systems involved in the development of Alzheimer's disease and the obtained SRP values are in good agreement with those reported previously by means of MP2 calculations. Iron complexes play a key role in the development of neurological disorders, such as Alzheimer's disease. We provide a computational protocol based on DFT for the calculation of standard reduction potentials of iron complexes relevant to Alzheimer's disease.![]()
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Affiliation(s)
- Adrián L. Orjuela
- Departamento de Química, Universidad Nacional de Colombia-Sede Bogotá, 111321, Colombia
| | - Francisco Núñez-Zarur
- Facultad de Ciencias Básicas, Universidad de Medellín, Carrera 87 No 30-65, 050026 Medellín, Colombia
| | - Jorge Alí-Torres
- Departamento de Química, Universidad Nacional de Colombia-Sede Bogotá, 111321, Colombia
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10
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Arumugam K, Burton NA. Disproportionation of the Uranyl(V) Coordination Complexes in Aqueous Solution through Outer-Sphere Electron Transfer. Inorg Chem 2021; 60:18832-18842. [PMID: 34847326 DOI: 10.1021/acs.inorgchem.1c02575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Among the linear actinyl(VI/V) cations, the uranyl(V) species are particularly intriguing because they are unstable and exhibit a unique behavior to undergo H+ promoted disproportionation in aqueous solution and form stable uranyl(VI) and U(IV) complexes. This study uses density functional theory (DFT) combined with the conductor-like polarizable continuum model approach to investigate [UO2]2+/+ to [UIVO2] reduction free energies (RFEs) and explores the stability of uranyl(V) complexes in aqueous solution through computing disproportionation free energies (DFEs) for an outer-sphere electron transfer process. In addition to the aqua complex (U1), another three commonly encountered ligands such as chloride (U2), acetate (U3), and carbonate (U4) in aqueous environmental conditions are taken into account. For the U1 complex, the computed 1e- (V/IV) and 2e- (VI/IV) RFEs are in good agreement with experiments. The computed DFEs reveal that the presence of H+ is imperative for the disproportionation to take place. Although the presence of the alkali cations favors the disproportionation to some extent, they cannot fully make the reaction thermodynamically feasible. For the anionic complexes, the high negative charge does not allow for the formation of a cation-cation encounter complex due to Coulombic repulsion. Furthermore, an additional factor is the ligand exchange reaction which is also an energy-demanding step. Therefore, the current study examined the Kern-Orlemann mechanism and our results validate the mechanism based on DFT computed DFEs and propose that for the anionic complexes, an outer-sphere electron transfer is highly probable and our computed protonation free energies further support this claim.
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Affiliation(s)
- Krishnamoorthy Arumugam
- Department of Chemistry, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Neil A Burton
- Department of Chemistry, School of Natural Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
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11
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Liu L, Zhang C, Jiang W, Li X, Dai Y, Jia H. Understanding the sorption behaviors of heavy metal ions in the interlayer and nanopore of montmorillonite: A molecular dynamics study. JOURNAL OF HAZARDOUS MATERIALS 2021; 416:125976. [PMID: 34492884 DOI: 10.1016/j.jhazmat.2021.125976] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 04/21/2021] [Accepted: 04/23/2021] [Indexed: 06/13/2023]
Abstract
The molecular-scale adsorption mechanism of heavy metal ions in the interlayer and nanopore regions of montmorillonite (MMT) were investigated by molecular dynamics simulations. Three typical heavy metals (zinc, cadmium, and lead) were selected as the model ions, and two types of MMT (Arizona and Wyoming) were considered. The results showed that Cd2+ and Pb2+ can form both inner- and outer-sphere complexes on Wyoming MMT, while Zn2+ only formed outer-sphere complex due to the stronger hydration interaction of Zn2+ than Cd2+ and Pb2+. For Arizona MMT, all of the three ions only formed outer-sphere complexes on its interlayer and external basal surface in which the cations remained a fully hydrated state. The calculated diffusion coefficients of three cations in interlayer and nanopore indicated that their diffusion abilities were significantly impaired, implying that MMT adsorbents have a strong ability to fix and retard heavy metal ions. The derived results and mechanisms are instrumental to a profound understanding of the transport and retention of heavy metal elements in subsurface environments, and provide guidance for the management of heavy metal pollution.
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Affiliation(s)
- Libin Liu
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China
| | - Chi Zhang
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China; State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Northwest A&F University, Yangling 712100, China.
| | - Wenjun Jiang
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China
| | - Xiong Li
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China; State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Northwest A&F University, Yangling 712100, China
| | - Yunchao Dai
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China; State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Northwest A&F University, Yangling 712100, China
| | - Hanzhong Jia
- Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China; State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Northwest A&F University, Yangling 712100, China.
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12
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Dunlop D, Večeřa M, Gyepes R, Kubát P, Lang K, Horáček M, Pinkas J, Šimková L, Liška A, Lamač M. Luminescent Cationic Group 4 Metallocene Complexes Stabilized by Pendant N-Donor Groups. Inorg Chem 2021; 60:7315-7328. [PMID: 33945274 DOI: 10.1021/acs.inorgchem.1c00461] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cationic group 4 metallocene complexes with pendant imine and pyridine donor groups were prepared as stable crystalline [B(C6F5)4]- salts either by protonation of the intramolecularly bound ketimide moiety in neutral complexes [(η5-C5Me5){η5-C5H4CMe2CMe2C(R)═N-κN}MCl] (M = Ti, Zr, Hf; R = t-Bu, Ph) by PhNMe2H+[B(C6F5)4]- to give [(η5-C5Me5){η5-C5H4CMe2CMe2C(R)═NH-κN}MCl]+[B(C6F5)4]- or by chloride ligand abstraction from the complexes [(η5-C5Me5)(η5-C5H4CMe2CH2C5H4N)MCl2] (M = Ti, Zr) by Li[B(C6F5)4]·2.5Et2O to give [(η5-C5Me5)(η5-C5H4CMe2CH2C5H4N-κN)MCl]+[B(C6F5)4]-. Solid state structures of the new compounds were established by X-ray diffraction analysis, and their electrochemical behavior was studied by cyclic voltammetry. The cationic complexes of Zr and Hf, compared to the corresponding neutral species, exhibited significantly enhanced luminescence predominantly from triplet ligand-to-metal (3LMCT) excited states with lifetimes up to 62 μs and quantum yields up to 58% in the solid state. DFT calculations were performed to explain the structural features and optical and electrochemical properties of the complexes.
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Affiliation(s)
- David Dunlop
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic.,Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 128 40 Praha 2, Czech Republic
| | - Miloš Večeřa
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Róbert Gyepes
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic.,Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 128 40 Praha 2, Czech Republic
| | - Pavel Kubát
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Kamil Lang
- Institute of Inorganic Chemistry of the Czech Academy of Sciences, 250 68 Husinec-Řež, Czech Republic
| | - Michal Horáček
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Jiří Pinkas
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Ludmila Šimková
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Alan Liška
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
| | - Martin Lamač
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Praha 8, Czech Republic
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13
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Criton T, Vilona D, Jacob G, Médebielle M, Dumont E, Joucla L, Lacôte E. Synthesis and Properties of Higher Nuclearity Polyazanes. Chemistry 2021; 27:3670-3674. [PMID: 33369892 DOI: 10.1002/chem.202004830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Indexed: 11/07/2022]
Abstract
Polyazanes (i.e., higher nuclearity homologues of hydrazines) with increasing numbers of bound nitrogen atoms (from 3 to 5), including the first pentazane ever described, were prepared by the addition of lower-order polyazanes to diazo reagents. A structure was obtained. It was shown that the polynitrogen chains adopt a helical conformation. DFT modeling shows that the arrangement persists in solution. Although the polyazanes are all reducing agents, they become less so as the number of nitrogens increases.
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Affiliation(s)
- Thomas Criton
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, CNES, ArianeGroup, LHCEP, UMR 5278, Bât. Raulin, 2 rue Victor Grignard, 69622, Villeurbanne, France
| | - Debora Vilona
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, CNES, ArianeGroup, LHCEP, UMR 5278, Bât. Raulin, 2 rue Victor Grignard, 69622, Villeurbanne, France
| | - Guy Jacob
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, CNES, ArianeGroup, LHCEP, UMR 5278, Bât. Raulin, 2 rue Victor Grignard, 69622, Villeurbanne, France
| | - Maurice Médebielle
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, CPE Lyon, INSA Lyon, ICBMS, UMR 5246, Bât. Lederer, 1 rue Victor Grignard, 69622, Villeurbanne, France
| | - Elise Dumont
- Univ Lyon, ENS Lyon, Université Claude Bernard Lyon 1, CNRS, LC, UMR 5182, 46 allée d'Italie, 69364, Lyon Cedex 07, France
| | - Lionel Joucla
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, CNES, ArianeGroup, LHCEP, UMR 5278, Bât. Raulin, 2 rue Victor Grignard, 69622, Villeurbanne, France
| | - Emmanuel Lacôte
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, CNES, ArianeGroup, LHCEP, UMR 5278, Bât. Raulin, 2 rue Victor Grignard, 69622, Villeurbanne, France
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14
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Talha Yassia K, Belkhiri L, Costuas K, Boucekkine A. How the Ancillary Ligand X Drives the Redox Properties of Biscyclopentadienyl Pentavalent Uranium Cp 2U(═N-Ar)X Complexes. Inorg Chem 2021; 60:2203-2218. [PMID: 33481573 DOI: 10.1021/acs.inorgchem.0c02908] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Relativistic zero order regular approximation (ZORA) density functional theory computations, coupled with the conductor-like screening model for solvation effects, are used to investigate the redox properties of a series of biscyclopentadienyl pentavalent uranium(V) complexes Cp2U(═N-Ar)X (Ar = 2,6-Me2-C6H3; X = OTf, C6F5, SPh, C═CPh, NPh2, Ph, Me, OPh, N(TMS)2, N═CPh2). Regarding the UV/UIV and UVI/UV couple systems, a linear correlation (R2 ∼ 0.99) is obtained at the ZORA/BP86/TZP level, between the calculated ionization energies and the measured experimental E1/2 half-wave oxidation potentials (UVI/UV) and between the electron affinities and the reduction potentials E1/2 (UV/UIV). The study brings to light the importance of solvation effects that are needed in order to achieve a good agreement between the theory and experiment. Introducing spin-orbit coupling corrections slightly improves this agreement. Both the singly occupied molecular orbital and the lowest unoccupied molecular orbital of the neutral UV complexes exhibit a majority 5f orbital character. The frontier molecular orbitals show a substantial ancillary ligand X σ and/or π character that drives the redox properties. Moreover, our investigations allow estimating the redox potentials of the X = Ph, X = C6F5, and N(TMS)2 UV complexes for which no experimental electrochemical data exist.
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Affiliation(s)
- Khadidja Talha Yassia
- Laboratoire de Physique Mathématique et Subatomique LPMS, Département de Chimie, Université des Frères Mentouri Constantine 1, 25017 Constantine, Algeria
| | - Lotfi Belkhiri
- Laboratoire de Physique Mathématique et Subatomique LPMS, Département de Chimie, Université des Frères Mentouri Constantine 1, 25017 Constantine, Algeria
| | - Karine Costuas
- Univ Rennes, ISCR UMR 6226 CNRS-Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - Abdou Boucekkine
- Univ Rennes, ISCR UMR 6226 CNRS-Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex, France
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15
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Loipersberger M, Cabral DGA, Chu DBK, Head-Gordon M. Mechanistic Insights into Co and Fe Quaterpyridine-Based CO 2 Reduction Catalysts: Metal-Ligand Orbital Interaction as the Key Driving Force for Distinct Pathways. J Am Chem Soc 2021; 143:744-763. [PMID: 33400528 DOI: 10.1021/jacs.0c09380] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Both [CoII(qpy)(H2O)2]2+ and [FeII(qpy)(H2O)2]2+ (with qpy = 2,2':6',2″:6'',2‴-quaterpyridine) are efficient homogeneous electrocatalysts and photoelectrocatalysts for the reduction of CO2 to CO. The Co catalyst is more efficient in the electrochemical reduction, while the Fe catalyst is an excellent photoelectrocatalyst ( ACS Catal. 2018, 8, 3411-3417). This work uses density functional theory to shed light on the contrasting catalytic pathways. While both catalysts experience primarily ligand-based reductions, the second reduction in the Co catalyst is delocalized onto the metal via a metal-ligand bonding interaction, causing a spin transition and a distorted ligand framework. This orbital interaction explains the experimentally observed mild reduction potential and slow kinetics of the second reduction. The decreased hardness and doubly occupied dz2-orbital facilitate a σ-bond with the CO2-π* in an η1-κC binding mode. CO2 binding is only possible after two reductions resulting in an EEC mechanism (E = electron transfer, C = chemical reaction), and the second protonation is rate-limiting. In contrast, the Fe catalyst maintains a Lewis acidic metal center throughout the reduction process because the metal orbitals do not strongly mix with the qpy-π* orbitals. This allows binding of the activated CO2 in an η2-binding mode. This interaction stabilizes the activated CO2 via a π-type interaction of a Fe-t2g orbital and the CO2-π* and a dative bond of the oxygen lone pair. This facilitates CO2 binding to a singly reduced catalyst resulting in an ECE mechanism. The barrier for CO2 addition and the second protonation are higher than those for the Co catalyst and rate-limiting.
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Affiliation(s)
- Matthias Loipersberger
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Delmar G A Cabral
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Daniel B K Chu
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Martin Head-Gordon
- Department of Chemistry, University of California, Berkeley, California 94720, United States.,Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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16
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Loipersberger M, Cabral DGA, Chu DBK, Head-Gordon M. Mechanistic Insights into Co and Fe Quaterpyridine-Based CO 2 Reduction Catalysts: Metal–Ligand Orbital Interaction as the Key Driving Force for Distinct Pathways. J Am Chem Soc 2021. [DOI: 10.1021/jacs.0c09380 and 21=21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matthias Loipersberger
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Delmar G. A. Cabral
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Daniel B. K. Chu
- Department of Chemical Engineering, University of California, Santa Barbara, California 93106, United States
| | - Martin Head-Gordon
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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17
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Valdéz-Camacho JR, Ramírez-Solís A, Escalante J, Ruiz-Azuara L, Hô M. Theoretical determination of half-wave potentials for phenanthroline-, bipyridine-, acetylacetonate-, and glycinate-containing copper (II) complexes. J Mol Model 2020; 26:191. [PMID: 32617735 DOI: 10.1007/s00894-020-04453-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 06/21/2020] [Indexed: 11/30/2022]
Abstract
We report a protocol for the evaluation of theoretical half-wave potential (E1/2) using a set of 22 mixed chelate copper (II) complexes containing 1,10-phenanthroline and 2,2'-bipyridine derivatives as primary ligands, and acetylacetonate or glycinate as secondary ligands (formally from the Casiopeínas® family) for which accurate experimental values were determined in a 2/5 mixture of ethanol/water. We have calibrated the BP86, PBE, PBE0, B3LYP, M06-2X, and ω-B97XD functionals, using the Los Alamos LANL2DZ and Stuttgart-Köln SDDAll effective core potentials for the Cu and Fe atoms and the 6-311+G* basis set for the C, H, O, and N atoms. To address the solvent effects, we have saturated the first solvation shell with up to 9 water molecules for the explicit model and compared it with the Continuum Like-Polarizable Continuum Model (CPCM) implicit solvent scheme. We found that the PBE/LANL2DZ-6-311+G* protocol (with the CPCM implicit solvent scheme with an effective dielectric constant ε = 64.9121 for the 2/5 mixture of ethanol/water) yields the overall best performance. The theoretical values are compared with experimental data, three of which are reported here for the first time. We find good correlations between the theoretical and experimental E1/2 values for the 2,2'-bipyridine derivatives (R2 = 0.987, MAE = 86 mV) and 1,10-phenanthroline derivatives (R2 = 0.802, MAE = 58.4 mV). The correlation trends have been explained in terms of the copper atom's ability to be reduced in the presence of the ligands. The Gibbs free energy differences at 298 K obtained for the redox reactions show that the more flexible secondary ligands (acetylacetonate) lead to larger entropic contributions which, as expected, increase the average MAE values as compared with the more rigid ligands (glycine). The present protocol yields lower MAEs as compared with previous approaches for similar mixed and flexible Cu(II) complexes.
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Affiliation(s)
- Jonathan Román Valdéz-Camacho
- Centro de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, 62209, Cuernavaca, Morelos, Mexico
| | - Alejandro Ramírez-Solís
- Centro de Investigación en Ciencias-IICBA, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, 62209, Cuernavaca, Morelos, Mexico
| | - Jaime Escalante
- Centro de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, 62209, Cuernavaca, Morelos, Mexico
| | - Lena Ruiz-Azuara
- Facultad de Química, Departamento de Química Inorgánica y Nuclear, Universidad Nacional Autónoma de México, Av. Universidad 3000, 04510, México, DF, Mexico
| | - Minhhuy Hô
- Centro de Investigaciones Químicas-IICBA, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, 62209, Cuernavaca, Morelos, Mexico.
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18
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Optical and morphological properties and in silico studies on metallophthalocyanines containing pyridyloxy moieties. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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19
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Hesabi N, Ebrahimi A. The electrochemical properties and PIM1 kinase enzyme inhibition of some 2-(hydroxy phenyl amino) naphthalene-1,4-dione derivatives. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.112874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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20
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Bani-Yaseen AD, Elbashier E. Computational Insights on the Electrocatalytic Behavior of [Cp*Rh] Molecular Catalysts Immobilized on Graphene for Heterogeneous Hydrogen Evolution Reaction. Sci Rep 2020; 10:5777. [PMID: 32238849 PMCID: PMC7113254 DOI: 10.1038/s41598-020-62758-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 03/13/2020] [Indexed: 12/03/2022] Open
Abstract
The heterogeneous metal-based molecular electrocatalyst can typically exhibit attractive features compared to its homogeneous analogue including recoverability and durability. As such, it is necessary to evaluate the electrocatalytic behavior of heterogenized molecular catalysts of interest toward gaining insights concerning the retainability of such behaviors while benefiting from heterogenization. In this work, we examined computationally the electrochemical properties of nanographene-based heterogenized molecular complexes of Rhodium. We assessed, as well, the electrocatalytic behavior of the heterogenized molecular catalyst for hydrogen evolution reaction (HER). Two electrochemical pathways were examined, namely one- and two-electron electrochemical reduction pathways. Interestingly, it is computationally demonstrated that [RhIII(Cp*)(phen)Cl]+-Gr can exhibit redox and electrocatalytic properties for HER that are comparable to its homogeneous analogue via a two-electron reduction pathway. On the other hand, the one-electron reduction pathway is notably found to be less favorable kinetically and thermodynamically. Furthermore, molecular insights are provided with respect to the HER employing molecular orbitals analyses and mechanistic aspects. Importantly, our findings may provide insights toward designing more efficient graphene-based molecular heterogeneous electrocatalysts for more efficient energy production.
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Affiliation(s)
- Abdulilah Dawoud Bani-Yaseen
- Department of Chemistry & Earth Sciences, College of Arts & Science, Qatar University, P.O. Box 2713, Doha, State of Qatar.
| | - Elkhansa Elbashier
- Department of Chemistry & Earth Sciences, College of Arts & Science, Qatar University, P.O. Box 2713, Doha, State of Qatar
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21
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Graphdiyne-actinyl complexes as potential catalytic materials: A DFT perspective from their structural, bonding, electronic and redox properties. ARAB J CHEM 2020. [DOI: 10.1016/j.arabjc.2019.10.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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22
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Mondal P, Schwinn K, Huix-Rotllant M. Impact of the redox state of flavin chromophores on the UV–vis spectra, redox and acidity constants and electron affinities. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2019.112164] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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23
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Arumugam K, Burton NA. Uranyl-Bound Tetra-Dentate Non-Innocent Ligands: Prediction of Structure and Redox Behaviour Using Density Functional Theory. Chemphyschem 2019; 20:1869-1878. [PMID: 31063234 DOI: 10.1002/cphc.201900301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/02/2019] [Indexed: 12/28/2022]
Abstract
Computational methods have been applied to understand the reduction potentials of [UO2 -salmnt-L] complexes (L=pyridine, DMSO, DMF and TPPO), and their redox behavior is compared with previous experiments in dichloromethane solution. Since the experimental results were inconclusive regarding the influence of the uranyl-bound tetra-dentate 'salmnt' ligand, here we will show that salmnt acts as a redox-active ligand and exhibits non-innocent behavior to interfere with the otherwise expected one-electron metal (U) reduction. We have employed two approaches to determine the uranyl (VI/V) reduction potentials, using a direct study of one-electron reduction processes and an estimation of the overall reduction using isodesmic reactions. Hybrid density functional theory (DFT) methods were combined with the Conductor-like Polarizable Continuum Model (CPCM) to account for solvation effects. The computationally predicted one-electron reduction potentials for the range of [UO2 -salmnt-L] complexes are in excellent agreement with shoulder peaks (∼1.4 eV) observed in the cyclic voltammetry experiments and clearly correlate with ligand reduction. Highly conjugated pi-bonds stabilize the ligand based delocalized orbital relative to the localized U f-orbitals, and as a consequence, the ligand traps the incoming electron. A second reduction step results in metal U(VI) to U(V) reduction, in good agreement with the experimentally assigned uranyl (VI/V) reduction potentials.
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Affiliation(s)
- Krishnamoorthy Arumugam
- School of Chemistry, The University of Manchester, Oxford Road, Manchester, United Kingdom.,Current address: National Post Doctoral Fellow (NPDF) Simulation Center for Atomic and Nanoscale Materials (SCANMAT), Central University of Tamil Nadu, Thiruvarur, Tamil Nadu-, 610101, India'
| | - Neil A Burton
- School of Chemistry, The University of Manchester, Oxford Road, Manchester, United Kingdom
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24
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Arumugam K, Renock D, Becker U. The basis for reevaluating the reactivity of pyrite surfaces: spin states and crystal field d-orbital splitting energies of bulk, terrace, edge, and corner Fe(ii) ions. Phys Chem Chem Phys 2019; 21:6415-6431. [PMID: 30839022 DOI: 10.1039/c8cp05459b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pyrite, one of the most important minerals to catalyze redox reactions in nature and a bulk low-spin Fe mineral, needs to provide high-spin Fe on surfaces to moderate spin-forbidden transitions. Here, the spin state of pyrite is investigated using density functional theory (DFT) calculations on cluster and periodic models. The energies of clusters FexS2x (where x = 4, 8, 16, and 32) were calculated as a function of total spin and different up/down spin configurations. The undercoordinated Fe on surfaces, edges, and corners were found to provide intermediate and high-spin Fe necessary for catalysis. Generally, the lower the crystal field splitting energy (CFSE), Δ, for a particular Fe atom, the higher is the spin density. Pyrite bulk (3D) and surfaces (2D) (+ water to mimic aqueous systems) were examined. The calculated bulk band gap (0.95 eV) is in excellent agreement with previous reports. For the surface, a conducting state is predicted. The calculated CFSE for bulk Fe(ii) in pyrite (∼2.2 eV) agrees with previous CFT results; due to surface states, this CFSE decreases to ∼1 eV on terraces. This study highlights the importance of accurately describing the spin state of pyrite.
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Affiliation(s)
- Krishnamoorthy Arumugam
- Department of Earth and Environmental Sciences, University of Michigan, 1100 North University Avenue, 2534 NUB, Ann Arbor, MI 48109-1005, USA.
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25
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Zhang FQ, Gao JP, Yan LK, Guan W, Yao RX, Zhang XM. Unveiling the relative stability and proton binding of non-classical Wells-Dawson isomers of [(NaF 6)W 18O 54(OH) 2] 7- and [(SbO 6)W 18O 54(OH) 2] 9-: a DFT study. Dalton Trans 2018; 46:16145-16158. [PMID: 29130092 DOI: 10.1039/c7dt03200e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Density functional theory calculations combined with the energy and building-block decomposition analyses have been carried out to investigate the structures, stability orders, redox potentials and proton binding of the six Baker-Figgis isomers (α, β, γ, α*, β* and γ*) of [(SbO6)W18O54(OH)2]9- {H2SbW18} and [(NaF6)W18O54(OH)2]7- {H2NaW18} anions at the level of PBEsol-D3/TZP. Both bonding energy and Gibbs free energy analyses exhibit that the two non-classical Wells-Dawson (WD) species behave quite differently from each other. The pyroanimonate {H2SbW18}, with a stability order of γ* > β* > α > α* > β > γ, is a non-classical WD species, while the hexafluoride {H2NaW18} (α > β > γ > γ* > β* > α*) is a transition intermediate between classical and non-classical WD types, possessing both non-classical ([XW18O60(OH)2]n-, X = I, Te and W) and classical [Si2W18O62]8- properties. Energy decomposition analyses (EDA) reveal that spatial arrangement (Ehost), host-guest fragment interaction energy (FIE), and structural distortion energy (DE) are three key factors governing the relative stability of isomers; among these, DE is always dominant, while FIE and Ehost are subordinated but are still important. Building-block decomposition analyses (BDA) disclose that the octahedral {MO6} units of the equatorial belt, particularly the staggered belt, are always more distorted than those of the two polar caps inside each structure. The theoretical redox potentials demonstrate that the oxidizing power increases with a trend of α < β < γ and α* < β* < γ* for both species, and the first redox potential is closely related to the energy level of the LUMO of each anion. Evaluation of the proton inclusion energies suggests that {H2NaW18} can only embed two protons, while {H2SbW18} may encapsulate four; the number of embedded protons is controlled by both the charge of the heteroatom X and the volume of the tetrahedral {O4}/{OF3} cavity.
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Affiliation(s)
- Fu-Qiang Zhang
- School of Chemistry & Material Science, Shanxi Normal University, Linfen, P. R. China.
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26
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Anjali BA, Suresh CH. Predicting reduction potentials of 1,3,6-triphenyl fulvenes using molecular electrostatic potential analysis of substituent effects. J Comput Chem 2018; 39:881-888. [PMID: 29322538 DOI: 10.1002/jcc.25164] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 12/20/2017] [Accepted: 12/22/2017] [Indexed: 11/06/2022]
Abstract
The influence of mono- and multiple substituent effect on the reduction potential (E0 ) of 1,3,6-triphenyl fulvenes is investigated using B3LYP-SMD/6-311+G(d,p) level density functional theory. The molecular electrostatic potential (MESP) minimum at the fulvene π-system (Vmin ) and the change in MESP at any of the fulvene carbon atoms (ΔVC ) for both neutral and reduced forms are used as excellent measures of substituent effect from the para and meta positions of the 1,3 and 6-phenyl moieties. Substitution at 6-phenyl para position has led to significant change in E0 than any other positions. By applying the additivity rule of substituent effects, an equation in ΔVC is derived to predict E0 for multiply substituted fulvenes. Further, E0 is predicted for a set of 2000 hexa-substituted fulvene derivatives where the substituents and their positions in the system are chosen in a random way. The calculated E0 agreed very well with the experimental E0 reported by Godman et al. Predicting E0 solely by substituent effect offers a simple and powerful way to select suitable combinations of substituents on fulvene system for light harvesting applications. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Bai Amutha Anjali
- Chemical Sciences and Technology Division, Academy of Scientific & Innovative Research (AcSIR), CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, 695019, India
| | - Cherumuttathu H Suresh
- Chemical Sciences and Technology Division, Academy of Scientific & Innovative Research (AcSIR), CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum, 695019, India
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27
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Anjali BA, Suresh CH. Electronic effect of ligands vs. reduction potentials of Fischer carbene complexes of chromium: a molecular electrostatic potential analysis. NEW J CHEM 2018. [DOI: 10.1039/c8nj04184a] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular electrostatic potential at the chromium centre (VCr) emerges as a powerful predictor of reduction potential (E0).
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Affiliation(s)
- Bai Amutha Anjali
- Chemical Sciences and Technology Division
- CSIR-National Institute for Interdisciplinary Science and Technology
- Trivandrum 695019
- India
- Academy of Scientific & Innovative Research (AcSIR)
| | - Cherumuttathu H. Suresh
- Chemical Sciences and Technology Division
- CSIR-National Institute for Interdisciplinary Science and Technology
- Trivandrum 695019
- India
- Academy of Scientific & Innovative Research (AcSIR)
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28
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Chaparro D, Alí-Torres J. Assessment of the isodesmic method in the calculation of standard reduction potential of copper complexes. J Mol Model 2017; 23:283. [PMID: 28936691 DOI: 10.1007/s00894-017-3469-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 09/06/2017] [Indexed: 11/26/2022]
Abstract
Molecular phenomena involving electron transfer and reduction/oxidation processes are of the utmost importance in chemistry. However, accurate computational calculations of standard reduction potentials (SRPs) for transition metal complexes are still challenging. For this reason, some computational strategies have been proposed in order to overcome the main limitations in SRP calculations for copper complexes. However, these strategies are limited to particular coordination spheres and do not represent a general methodology. In this work, we present standard reduction potential calculations for copper complexes in aqueous solution covering a wide range of coordination spheres. These calculations were performed using the M06-2X density functional, and by employing the direct and isodesmic approaches. Result analysis reveals that values obtained with the use of the isodesmic method are in better agreement with experimental values than those obtained from the direct method (mean unsigned error 0.39 V with the direct and 0.08 V with the isodesmic method). This approach provides values with errors comparable to the experimental uncertainty due to the proper cancellation of computational errors. These results strongly suggest the isodesmic approach as an adequate methodology for the calculation of SRPs for copper complexes with diverse coordination spheres. Graphical Abstract Comparison between direct and isodesmic methods in the calculation of standard reduction potentials for copper complexes using DFT methods.
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Affiliation(s)
- Diego Chaparro
- Department of Chemistry, Universidad Nacional de Colombia, Av. Cra 30 # 45-03, Bogotá, Colombia
| | - Jorge Alí-Torres
- Department of Chemistry, Universidad Nacional de Colombia, Av. Cra 30 # 45-03, Bogotá, Colombia.
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Intermolecular hydrogen bonds between 1,4-benzoquinones and HF molecule: Synergetic effects, reduction potentials and electron affinities. J Mol Graph Model 2017; 77:86-93. [PMID: 28850896 DOI: 10.1016/j.jmgm.2017.08.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 08/10/2017] [Accepted: 08/11/2017] [Indexed: 11/20/2022]
Abstract
Some biological activities of quinones can be attributed to the H-bonding ability of acceptor oxygen atoms. According to the results obtained from the quantum mechanical calculations performed on a wide variety of complexes between the 1,4-benzoquinone (BQ) derivatives and HF molecules, the interplay between H-bonds and individual H-bond interaction energies (EHB) can be affected by the substituents placed on the six-membered ring of BQ. The total binding energies of complexes become more negative by the electron donating substituents (EDSs) while the changes are reversed by the electron withdrawing substituents (EWSs). The mutual interplay between the X-BQ⋯(HF)n (n=1-3) interactions has been investigated using the geometrical parameters, synergetic energies (SE) and the EHB values. Hydrogen bonding decreases the reduction potentials (E0red) and increases the electron affinities (EA) of X-BQ derivatives. Linear relationships have been observed between the E0red (and EA) values and the Hammett constants of substituents.
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Flores-Leonar MM, Moreno-Esparza R, Ugalde-Saldívar VM, Amador-Bedolla C. Correlating Properties in Iron(III) Complexes: A DFT Description of Structure, Redox Potential and Spin Crossover Phenomena. ChemistrySelect 2017. [DOI: 10.1002/slct.201700547] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Martha M. Flores-Leonar
- Facultad de Química (UNAM); Edificio B; Av. Universidad 3000, Coyoacán Ciudad de México 04510 México
| | - Rafael Moreno-Esparza
- Facultad de Química (UNAM); Edificio B; Av. Universidad 3000, Coyoacán Ciudad de México 04510 México
| | - Víctor M. Ugalde-Saldívar
- Facultad de Química (UNAM); Edificio B; Av. Universidad 3000, Coyoacán Ciudad de México 04510 México
| | - Carlos Amador-Bedolla
- Facultad de Química (UNAM); Edificio B; Av. Universidad 3000, Coyoacán Ciudad de México 04510 México
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31
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Flores-Leonar MM, Moreno-Esparza R, Ugalde-Saldívar VM, Amador-Bedolla C. Further insights in DFT calculations of redox potential for iron complexes: The ferrocenium/ferrocene system. COMPUT THEOR CHEM 2017. [DOI: 10.1016/j.comptc.2016.11.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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32
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Dudkina YB, Kholin KV, Gryaznova TV, Islamov DR, Kataeva ON, Rizvanov IK, Levitskaya AI, Fominykh OD, Balakina MY, Sinyashin OG, Budnikova YH. Redox trends in cyclometalated palladium(ii) complexes. Dalton Trans 2017; 46:165-177. [DOI: 10.1039/c6dt03786k] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electrochemical and DFT studies on palladacycles revealed an increase in the metal–metal distance in the complexes leads to higher oxidation potentials.
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33
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Yu HS, Li SL, Truhlar DG. Perspective: Kohn-Sham density functional theory descending a staircase. J Chem Phys 2016; 145:130901. [DOI: 10.1063/1.4963168] [Citation(s) in RCA: 204] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Haoyu S. Yu
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA
| | - Shaohong L. Li
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA
| | - Donald G. Truhlar
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA
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34
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Isegawa M, Neese F, Pantazis DA. Ionization Energies and Aqueous Redox Potentials of Organic Molecules: Comparison of DFT, Correlated ab Initio Theory and Pair Natural Orbital Approaches. J Chem Theory Comput 2016; 12:2272-84. [PMID: 27065224 DOI: 10.1021/acs.jctc.6b00252] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The calculation of redox potentials involves large energetic terms arising from gas phase ionization energies, thermodynamic contributions, and solvation energies of the reduced and oxidized species. In this work we study the performance of a wide range of wave function and density functional theory methods for the prediction of ionization energies and aqueous one-electron oxidation potentials of a set of 19 organic molecules. Emphasis is placed on evaluating methods that employ the computationally efficient local pair natural orbital (LPNO) approach, as well as several implementations of coupled cluster theory and explicitly correlated F12 methods. The electronic energies are combined with implicit solvation models for the solvation energies. With the exception of MP2 and its variants, which suffer from enormous errors arising at least partially from the poor Hartree-Fock reference, ionization energies can be systematically predicted with average errors below 0.1 eV for most of the correlated wave function based methods studies here, provided basis set extrapolation is performed. LPNO methods are the most efficient way to achieve this type of accuracy. DFT methods show in general larger errors and suffer from inconsistent behavior. The only exception is the M06-2X functional which is found to be competitive with the best LPNO-based approaches for ionization energies. Importantly, the limiting factor for the calculation of accurate redox potentials is the solvation energy. The errors in the predicted solvation energies by all continuum solvation models tested in this work dominate the final computed reduction potential, resulting in average errors typically in excess of 0.3 V and hence obscuring the gains that arise from choosing a more accurate electronic structure method.
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Affiliation(s)
- Miho Isegawa
- Max Planck Institute for Chemical Energy Conversion, Stiftrasse 34-38, 45470 Mülheim and der Ruhr, Germany
| | - Frank Neese
- Max Planck Institute for Chemical Energy Conversion, Stiftrasse 34-38, 45470 Mülheim and der Ruhr, Germany
| | - Dimitrios A Pantazis
- Max Planck Institute for Chemical Energy Conversion, Stiftrasse 34-38, 45470 Mülheim and der Ruhr, Germany
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35
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Insights into the value of statistical models and relativistic effects for the investigation of halogenated derivatives of fluorescent probes. Theor Chem Acc 2016. [DOI: 10.1007/s00214-016-1862-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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36
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Anjali BA, Sayyed FB, Suresh CH. Correlation and Prediction of Redox Potentials of Hydrogen Evolution Mononuclear Cobalt Catalysts via Molecular Electrostatic Potential: A DFT Study. J Phys Chem A 2016; 120:1112-9. [DOI: 10.1021/acs.jpca.5b11543] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bai Amutha Anjali
- Chemical Sciences and Technology Division and ‡Academy of Scientific & Innovative Research (AcSIR), CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum 695019, India
| | - Fareed Bhasha Sayyed
- Chemical Sciences and Technology Division and ‡Academy of Scientific & Innovative Research (AcSIR), CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum 695019, India
| | - Cherumuttathu H. Suresh
- Chemical Sciences and Technology Division and ‡Academy of Scientific & Innovative Research (AcSIR), CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum 695019, India
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37
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Bao Z, Zhao HB, Qu N, Schreckenbach G, Pan QJ. Theoretical investigation of low-valent uranium and transuranium complexes of a flexible small-cavity macrocycle: structural, formation reaction and redox properties. Dalton Trans 2016; 45:15970-15982. [DOI: 10.1039/c6dt01930g] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Size matching of a flexible macrocycle with low-valent actinide(III/IV) ions as well as their bonding determines different coordination modes.
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Affiliation(s)
- Zhe Bao
- Key Laboratory of Functional Inorganic Material Chemistry of Education Ministry
- School of Chemistry and Materials Science
- Heilongjiang University
- Harbin
- China 150080
| | - Hong-Bo Zhao
- Key Laboratory of Functional Inorganic Material Chemistry of Education Ministry
- School of Chemistry and Materials Science
- Heilongjiang University
- Harbin
- China 150080
| | - Ning Qu
- Key Laboratory of Functional Inorganic Material Chemistry of Education Ministry
- School of Chemistry and Materials Science
- Heilongjiang University
- Harbin
- China 150080
| | | | - Qing-Jiang Pan
- Key Laboratory of Functional Inorganic Material Chemistry of Education Ministry
- School of Chemistry and Materials Science
- Heilongjiang University
- Harbin
- China 150080
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38
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Miranda-Quintana RA, Martínez González M, Ayers PW. Electronegativity and redox reactions. Phys Chem Chem Phys 2016; 18:22235-43. [DOI: 10.1039/c6cp03213c] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using the maximum hardness principle, we show that the oxidation potential of a molecule increases as its electronegativity increases and also increases as its electronegativity in its oxidized state increases.
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Affiliation(s)
| | - Marco Martínez González
- Laboratory of Computational and Theoretical Chemistry
- Faculty of Chemistry
- University of Havana
- Havana
- Cuba
| | - Paul W. Ayers
- Department of Chemistry & Chemical Biology
- McMaster University
- Hamilton
- Canada
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39
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Liu X, Cheng J, He M, Lu X, Wang R. Acidity constants and redox potentials of uranyl ions in hydrothermal solutions. Phys Chem Chem Phys 2016; 18:26040-26048. [DOI: 10.1039/c6cp03469a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a first principles molecular dynamics (FPMD) study of the structures, acidity constants (pKa) and redox potentials (E0) of uranyl (UO22+) from ambient conditions to 573 K.
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Affiliation(s)
- Xiandong Liu
- State Key Laboratory for Mineral Deposits Research
- School of Earth Sciences and Engineering
- Nanjing University
- Nanjing 210093
- P. R. China
| | - Jun Cheng
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen 361005
- P. R. China
- Department of Chemistry
| | - Mengjia He
- State Key Laboratory for Mineral Deposits Research
- School of Earth Sciences and Engineering
- Nanjing University
- Nanjing 210093
- P. R. China
| | - Xiancai Lu
- State Key Laboratory for Mineral Deposits Research
- School of Earth Sciences and Engineering
- Nanjing University
- Nanjing 210093
- P. R. China
| | - Rucheng Wang
- State Key Laboratory for Mineral Deposits Research
- School of Earth Sciences and Engineering
- Nanjing University
- Nanjing 210093
- P. R. China
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40
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Yan L, Lu Y, Li X. A density functional theory protocol for the calculation of redox potentials of copper complexes. Phys Chem Chem Phys 2016; 18:5529-36. [DOI: 10.1039/c5cp06638g] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The calculated redox potentials of copper complexes agree nicely with their corresponding experimental redox potentials.
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Affiliation(s)
- Liuming Yan
- Department of Chemistry
- College of Sciences
- Shanghai University
- Shanghai 200444
- China
| | - Yi Lu
- Department of Chemistry
- University of Illinois at Urbana-Champaign
- Urbana
- USA
| | - Xuejiao Li
- Department of Chemistry
- College of Sciences
- Shanghai University
- Shanghai 200444
- China
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41
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Sander M, Hofstetter TB, Gorski CA. Electrochemical analyses of redox-active iron minerals: a review of nonmediated and mediated approaches. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:5862-78. [PMID: 25856208 DOI: 10.1021/acs.est.5b00006] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Redox-active minerals are ubiquitous in the environment and are involved in numerous electron transfer reactions that significantly affect biogeochemical processes and cycles as well as pollutant dynamics. As a consequence, research in different scientific disciplines is devoted to elucidating the redox properties and reactivities of minerals. This review focuses on the characterization of mineral redox properties using electrochemical approaches from an applied (bio)geochemical and environmental analytical chemistry perspective. Establishing redox equilibria between the minerals and working electrodes is a major challenge in electrochemical measurements, which we discuss in an overview of traditional electrochemical techniques. These issues can be overcome with mediated electrochemical analyses in which dissolved redox mediators are used to increase the rate of electron transfer and to facilitate redox equilibration between working electrodes and minerals in both amperometric and potentiometric measurements. Using experimental data on an iron-bearing clay mineral, we illustrate how mediated electrochemical analyses can be employed to derive important thermodynamic and kinetic data on electron transfer to and from structural iron. We summarize anticipated methodological advancements that will further contribute to advance an improved understanding of electron transfer to and from minerals in environmentally relevant redox processes.
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Affiliation(s)
- Michael Sander
- †Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, Environmental Chemistry, Swiss Federal Institute of Technology (ETH), Universitätstrasse 16, 8092 Zurich, Switzerland
| | - Thomas B Hofstetter
- ‡Environmental Chemistry, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Ueberlandstrasse 133,8600 Duebendorf, Switzerland
| | - Christopher A Gorski
- §Civil and Environmental Engineering, The Pennsylvania State University, 212 Sackett Building, University Park, Pennsylvania 16802-1408, United States
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42
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Bogart JA, Lewis AJ, Schelter EJ. DFT study of the active site of the XoxF-type natural, cerium-dependent methanol dehydrogenase enzyme. Chemistry 2014; 21:1743-8. [PMID: 25421364 DOI: 10.1002/chem.201405159] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Indexed: 11/07/2022]
Abstract
Rare-earth metal cations have recently been demonstrated to be essential co-factors for the growth of the methanotrophic bacterium Methylacidiphilum fumariolicum SolV. A crystal structure of the rare-earth-dependent methanol dehydrogenase (MDH) includes a cerium cation in the active site. Herein, the Ce-MDH active site has been analyzed through DFT calculations. The results show the stability of the Ce(III)-pyrroloquinoline quinone (PQQ) semiquinone configuration. Calculations on the active oxidized form of this complex indicate a 0.81 eV stabilization of the PQQ(0) LUMO at cerium versus calcium, supporting the observation that the cerium cation in the active site confers a competitive advantage to Methylacidiphilum fumariolicum SolV. Using reported aqueous electrochemical data, a semi-empirical correlation was established based on cerium(IV/III) redox potentials. The correlation allowed estimation of the cerium oxidation potential of +1.35 V versus saturated calomel electrode (SCE) in the active site. The results are expected to guide the design of functional model complexes and alcohol-oxidation catalysts based on lanthanide complexes of biologically relevant quinones.
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Affiliation(s)
- Justin A Bogart
- Department of Chemistry, University of Pennsylvania, P. Roy and Diana T. Vagelos Laboratories, Philadlephia, PA 19104 (USA)
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