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Szczuka C, Eichel RA, Granwehr J. Gauging the importance of structural parameters for hyperfine coupling constants in organic radicals. RSC Adv 2023; 13:14565-14574. [PMID: 37188254 PMCID: PMC10177955 DOI: 10.1039/d3ra02476h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/08/2023] [Indexed: 05/17/2023] Open
Abstract
The identification of fundamental relationships between atomic configuration and electronic structure typically requires experimental empiricism or systematic theoretical studies. Here, we provide an alternative statistical approach to gauge the importance of structure parameters, i.e., bond lengths, bond angles, and dihedral angles, for hyperfine coupling constants in organic radicals. Hyperfine coupling constants describe electron-nuclear interactions defined by the electronic structure and are experimentally measurable, for example, by electron paramagnetic resonance spectroscopy. Importance quantifiers are computed with the machine learning algorithm neighborhood components analysis using molecular dynamics trajectory snapshots. Atomic-electronic structure relationships are visualized in matrices correlating structure parameters with coupling constants of all magnetic nuclei. Qualitatively, the results reproduce common hyperfine coupling models. Tools to use the presented procedure for other radicals/paramagnetic species or other atomic structure-dependent parameters are provided.
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Affiliation(s)
- Conrad Szczuka
- Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich GmbH 52425 Jülich Germany
| | - Rüdiger-A Eichel
- Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich GmbH 52425 Jülich Germany
- Institute of Physical Chemistry, RWTH Aachen University 52056 Aachen Germany
| | - Josef Granwehr
- Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich GmbH 52425 Jülich Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University 52056 Aachen Germany
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2
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Vogler S, Dietschreit JCB, Peters LDM, Ochsenfeld C. Important components for accurate hyperfine coupling constants: electron correlation, dynamic contributions, and solvation effects. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1772515] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Sigurd Vogler
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), Munich, Germany
| | | | - Laurens D. M. Peters
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), Munich, Germany
| | - Christian Ochsenfeld
- Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), Munich, Germany
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Auer AA, Tran VA, Sharma B, Stoychev GL, Marx D, Neese F. A case study of density functional theory and domain-based local pair natural orbital coupled cluster for vibrational effects on EPR hyperfine coupling constants: vibrational perturbation theory versus ab initio molecular dynamics. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1797916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
| | - Van Anh Tran
- MPI für Kohlenforschung, Mülheim an der Ruhr, Germany
| | - Bikramjit Sharma
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Bochum, Germany
| | | | - Dominik Marx
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Bochum, Germany
| | - Frank Neese
- MPI für Kohlenforschung, Mülheim an der Ruhr, Germany
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Witwicki M, Walencik PK, Jezierska J. How accurate is density functional theory in predicting spin density? An insight from the prediction of hyperfine coupling constants. J Mol Model 2019; 26:10. [PMID: 31834497 DOI: 10.1007/s00894-019-4268-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 11/25/2019] [Indexed: 01/30/2023]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy has been proven to be an important technique for studying paramagnetic systems. Probably, the most accessible EPR parameter and the one that provides a significant amount of information about molecular structure and spin density is the hyperfine coupling constant (HFCC). Hence, accurate quantum-chemical modeling of HFCCs is frequently essential to the adequate interpretation of EPR spectra. It requires the precise spin density, which is the difference between the densities of α- and β-electrons, and thus, its quality is expected to reflect the quality of the total electron density. The question of which approximate exchange-correlation density functional yields sufficiently accurate HFCCs, and thus, the spin density remains open. To assess the performance of well-established density functionals for calculating HFCCs, we used a series of 26 small paramagnetic species and compared the obtained results to the CCSD reference values. The performance of DFT was also tested on EPR-studied o-semiquinone radical interacting with water molecules and Mg2+ cation. The HFCCs were additionally calculated by the DLPNO-CCSD method, and this wave function-based technique was found superior to all functionals we tested. Although some functionals were found, on average, to be fairly efficient, we found that the most accurate functional is system-dependent, and therefore, the DLPNO-CCSD method should be preferred for theoretical investigations of the HFCCs and spin density.
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Affiliation(s)
- Maciej Witwicki
- Faculty of Chemistry, Wrocław University, ul. F. Joliot-Curie 14, 50-383, Wrocław, Poland.
| | - Paulina K Walencik
- Faculty of Chemistry, Wrocław University, ul. F. Joliot-Curie 14, 50-383, Wrocław, Poland
| | - Julia Jezierska
- Faculty of Chemistry, Wrocław University, ul. F. Joliot-Curie 14, 50-383, Wrocław, Poland
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Witwicki M, Jezierska J. Toward an Understanding of the Ambiguous Electron Paramagnetic Resonance Spectra of the Iminoxy Radical from o-Fluorobenzaldehyde Oxime: Density Functional Theory and ab Initio Studies. J Phys Chem A 2015; 119:9109-20. [PMID: 26258434 DOI: 10.1021/acs.jpca.5b06143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Iminoxy radicals (R1R2C═N—O•) possess an inherent ability to exist as E and Z isomers. Although isotropic hyperfine couplings for the species with R1 = H allow one to distinguish between E and Z, unequivocal assignment of the parameters observed in the EPR spectra of the radicals without the hydrogen atom at the azomethine carbon to the right isomer is not a simple task. The iminoxyl derived from o-fluoroacetophenone oxime (R1 = CH3 and R2 = o-FC6H5) appears to be a case in point. Moreover, for its two isomers the rotation of the o-FC6H5 group brings into existence the syn and anti conformers, depending on the mutual orientation of the F atom and C═N—O• group, making a description of hyperfine couplings to structure even more challenging. To accomplish this, a vast array of theoretical methods (DFT, OO-SCS-MP2, QCISD) was used to calculate the isotropic hyperfine couplings. The comparison between experimental and theoretical values revealed that the E isomer is the dominant radical form, for which a fast interconversion between anti and syn conformers is expected. In addition, the origin of the significant AF increase with solvent polarity was analyzed.
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Asher JR, Malkin VG, Malkina OL. Visualization of the four-component g-tensor density as a three-dimensional function. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Witwicki M. Theoretical Characterisation of Phosphinyl Radicals and Their Magnetic Properties: g Matrix. Chemphyschem 2015; 16:1912-25. [PMID: 25873130 DOI: 10.1002/cphc.201500121] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Indexed: 11/11/2022]
Abstract
The g matrices (g tensors) of various phosphinyl radicals (R2 P(.) ) were calculated using the DFT and multireference configuration interaction (MRCI) methods. The g matrices were distinctly dependent on the molecular structure of the radical. To thoroughly examine this dependence, the contributions from individual atoms and excited states were calculated. The former revealed the gain from the phosphorus atom to be preeminent unless PO or PS bonds are present in the radical molecule. The contributions owing to excited states arising from electronic transitions between doubly occupied molecular orbitals and the SOMO were clearly positive, as in the case of semiquinone and niroxide radicals. The transitions from the phosphorus lone pair were of paramount importance. Surprisingly, unlike for semiquinones and nitroxides, a significant negative contribution was observed from excitations from the SOMO to unoccupied molecular orbitals. For radicals with PO bonds, this contribution to the g2 component was dominant.
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Affiliation(s)
- Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, 14 F. Joliot-Curie St., Wroclaw 50-283 (Poland).
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Elgabarty H, Wolff M, Glaubitz A, Hinderberger D, Sebastiani D. First principles calculation of inhomogeneous broadening in solid-state cw-EPR spectroscopy. Phys Chem Chem Phys 2013; 15:16082-9. [PMID: 23985880 DOI: 10.1039/c3cp51938d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We present a scheme for the first-principles calculation of EPR lineshapes for continuous-wave-EPR spectroscopy (cw-EPR) of spin centers in complex chemical environments. We specifically focus on poorly characterized systems, e.g. powders and frozen glasses with variable microsolvation structures. Our approach is based on ab initio molecular dynamics simulations and ab initio calculations of the ensemble of g- and A-tensors along the trajectory. The method incorporates temperature effects as well as the full anharmonicity of the intra- and intermolecular degrees of freedom of the system. We apply this scheme to compute the lineshape of a prototypical spin probe, the nitrosodisulfonate dianionic radical (Fremy's salt), dissolved in a 50 : 50 mixture of water and methanol. We are able to determine the specific effect of variations of local solvent composition and microsolvation structure on the cw-EPR lineshape. Our molecular dynamics reveal a highly anisotropic solvation structure with distinct spatial preferences for water and methanol around Fremy's salt that can be traced back to a combination of steric and polar influences. The overall solvation structure and conformational preferences of Fremy's salt as found in our MD simulations agree very well with the results obtained from EPR and orientation-selective ENDOR spectroscopy performed on the frozen glass. The simulated EPR lineshapes show good agreement with the experimental spectra. When combined with our MD results, they characterize the lineshape dependence on local morphological fluctuations.
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Affiliation(s)
- Hossam Elgabarty
- Dahlem Center for Complex Quantum Systems (DCCQS), Physics Department, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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Witwicki M, Jezierska J. Effects of Solvents, Ligand Aromaticity, and Coordination Sphere on the g Tensor of Anionic o-Semiquinone Radicals Complexed by Mg2+ Ions: DFT Studies. J Phys Chem B 2011; 115:3172-84. [DOI: 10.1021/jp110515j] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, 14 F. Joliot-Curie St., Wroclaw 50-283, Poland
| | - Julia Jezierska
- Faculty of Chemistry, Wroclaw University, 14 F. Joliot-Curie St., Wroclaw 50-283, Poland
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Kossmann S, Kirchner B, Neese F. Performance of modern density functional theory for the prediction of hyperfine structure: meta-GGA and double hybrid functionals. Mol Phys 2010. [DOI: 10.1080/00268970701604655] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Rastrelli F, Bagno A. Predicting the ¹H and ¹³C NMR spectra of paramagnetic Ru(III) complexes by DFT. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2010; 48 Suppl 1:S132-S141. [PMID: 20821378 DOI: 10.1002/mrc.2666] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Nuclear shieldings, including the Fermi-contact and pseudocontact terms, have been calculated with density functional theory (DFT) (nonrelativistic and relativistic) methods in several Ru(III) complexes, thereby predicting (1)H and (13)C paramagnetic shifts. A fair agreement with experimental values is observed. Structural, magnetic and dynamic parameters have also been input to the Solomon-Bloembergen equation in order to predict signal lineshapes. It is shown that DFT-predicted paramagnetic shifts can greatly aid in obtaining and understanding NMR spectra of paramagnetic Ru(III) complexes.
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Affiliation(s)
- Federico Rastrelli
- Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo, 1-35131 Padova, Italy
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Přecechtělová J, Novák P, Munzarová ML, Kaupp M, Sklenář V. Phosphorus Chemical Shifts in a Nucleic Acid Backbone from Combined Molecular Dynamics and Density Functional Calculations. J Am Chem Soc 2010; 132:17139-48. [DOI: 10.1021/ja104564g] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Jana Přecechtělová
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic, and Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Petr Novák
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic, and Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Markéta L. Munzarová
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic, and Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Martin Kaupp
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic, and Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Vladimír Sklenář
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic, and Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany
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Witwicki M, Jezierska J. Protic and aprotic solvent effect on molecular properties and g-tensors of o-semiquinones with various aromacity and heteroatoms: A DFT study. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.05.063] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Houriez C, Ferré N, Siri D, Masella M. Further Insights into the Environmental Effects on the Computed Hyperfine Coupling Constants of Nitroxides in Aqueous Solution. J Phys Chem B 2009; 113:15047-56. [DOI: 10.1021/jp906828v] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Céline Houriez
- UMR 6264 Laboratoire Chimie Provence, Faculté des Sciences de Saint-Jérôme Case 521, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France, UMR 8000 Laboratoire de Chimie Physique, Université Paris-Sud 11, 91405 Orsay Cedex, France, and Laboratoire de Chimie du Vivant, Service d’ingénierie moléculaire des protéines, Institut de biologie et de technologies de Saclay, Commissariat à l’énergie atomique, Centre de Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Nicolas Ferré
- UMR 6264 Laboratoire Chimie Provence, Faculté des Sciences de Saint-Jérôme Case 521, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France, UMR 8000 Laboratoire de Chimie Physique, Université Paris-Sud 11, 91405 Orsay Cedex, France, and Laboratoire de Chimie du Vivant, Service d’ingénierie moléculaire des protéines, Institut de biologie et de technologies de Saclay, Commissariat à l’énergie atomique, Centre de Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Didier Siri
- UMR 6264 Laboratoire Chimie Provence, Faculté des Sciences de Saint-Jérôme Case 521, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France, UMR 8000 Laboratoire de Chimie Physique, Université Paris-Sud 11, 91405 Orsay Cedex, France, and Laboratoire de Chimie du Vivant, Service d’ingénierie moléculaire des protéines, Institut de biologie et de technologies de Saclay, Commissariat à l’énergie atomique, Centre de Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Michel Masella
- UMR 6264 Laboratoire Chimie Provence, Faculté des Sciences de Saint-Jérôme Case 521, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex 20, France, UMR 8000 Laboratoire de Chimie Physique, Université Paris-Sud 11, 91405 Orsay Cedex, France, and Laboratoire de Chimie du Vivant, Service d’ingénierie moléculaire des protéines, Institut de biologie et de technologies de Saclay, Commissariat à l’énergie atomique, Centre de Saclay, 91191 Gif-sur-Yvette Cedex, France
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Rastrelli F, Bagno A. Predicting the NMR Spectra of Paramagnetic Molecules by DFT: Application to Organic Free Radicals and Transition-Metal Complexes. Chemistry 2009; 15:7990-8004. [DOI: 10.1002/chem.200802443] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Asher JR, Kaupp M. Car-Parrinello molecular dynamics simulations and EPR property calculations on aqueous ubisemiquinone radical anion. Theor Chem Acc 2008. [DOI: 10.1007/s00214-007-0408-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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