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Optical and Magnetic Properties of Copper(II) Compounds
KTH, School of Biotechnology (BIO), Theoretical Chemistry.
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis encloses quantum chemical calculations and applications of a response function formalism recently implemented within the framework of density functional theory. The optical and magnetic properties of copper(II) molecular systems are the main goal of this work. In this work, the visible and near-infrared electronic transitions, which have shown a key role in studies on electronic structure and structure-function relationships of copper compounds, were investigated in order to explore the correlation of the positions and intensities of these transitions with the geometrical structures and their molecular distortions. The evaluation of solvent effects on the absorption spectra were successfully achieved, providing accurate and inedit computational insight of these effects for copper(II) complexes. Electron Paramagnetic Resonance (EPR) parameters, that is, the electronic g tensor and the hyperfine coupling constants, are powerful spectroscopic properties for investigating paramagnetic systems and were thoroughly analysed in this work in different molecular systems. Relativistic corrections generated by spin-orbit interactions or by scalar relativistic effects were taken into account in all calculations. In addition, we have designed a methodology for accurate evaluation of the electronic g tensors and hyperfine coupling tensors as well as for evaluation of solvent effects on these properties. It is found that this methodology is able to provide reliable and accurate results for EPR parameters of copper(II) molecular systems. The spin polarization effects on EPR parameters of square planar copper(II) complexes were also considered, showing that these effects give rise to significant contributions to the hyperfine coupling tensor, whereas the electronic g tensor of these complexes are only marginally affected by these effects. The evaluation of the leading-order relativistic corrections to the electronic g tensors of molecules with a doublet ground state has been also taken into account in this work. As a first application of the theory, the electronic g tensors of dihalogen anion radicals X$_2^-$ (X=F,~Cl,~Br,~I) have been investigated and the obtained results indicate that the spin--orbit interaction is responsible for the parallel component of the g tensor shift, while both the leading-order scalar relativistic and spin--orbit corrections are of minor importance for the perpendicular component of the g tensor in these molecules

since they effectively cancel each other. Overall, both optical and magnetic results show quantitative agreements with experiments, indicating that the methodologies employed form a practical way in study of copper(II) molecular systems including those of biological importance.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , vi, 53 p.
National Category
Industrial Biotechnology
Identifiers
URN: urn:nbn:se:kth:diva-4743ISBN: 978-91-7415-014-8 (print)OAI: oai:DiVA.org:kth-4743DiVA: diva2:13744
Public defence
2008-05-30, FA32, AlbaNova, Roslagstullsbacken, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100714Available from: 2008-05-12 Created: 2008-05-12 Last updated: 2010-07-14Bibliographically approved
List of papers
1. Modeling of EPR parameters of copper(II) aqua complexes
Open this publication in new window or tab >>Modeling of EPR parameters of copper(II) aqua complexes
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2007 (English)In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 332, no 2-3, 176-187 p.Article in journal (Refereed) Published
Abstract [en]

In this paper we report density functional theory calculations of the electronic g-tensor and hyperfine coupling constants of the copper dication in sixfold- and fivefold-coordination models of the first aqueous solvation sphere. The obtained results indicate that the electronic g-tensor of these copper complexes in combination with hyperfine coupling constants of copper in principle can be used to elucidate the coordination environment of the hydrated copper dication. In addition to these results, we have designed a methodology for accurate evaluation of electronic g-tensors and hyperfine coupling tensors in copper complexes, and demonstrate the applicability of this approach to copper dication aqua complexes.

Keyword
copper dication; EPR; DFT; g-tensor; hyperfine coupling tenser
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-8423 (URN)10.1016/j.chemphys.2006.11.015 (DOI)000244549500004 ()2-s2.0-33846818730 (Scopus ID)
Note
QC 20100714Available from: 2008-05-12 Created: 2008-05-12 Last updated: 2017-12-14Bibliographically approved
2. Conformations, structural transitions and visible near-infrared absorption spectra of four-, five- and six-coordinated Cu(II) aqua complexes
Open this publication in new window or tab >>Conformations, structural transitions and visible near-infrared absorption spectra of four-, five- and six-coordinated Cu(II) aqua complexes
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2009 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 11, no 3, 508-519 p.Article in journal (Refereed) Published
Abstract [en]

We have performed Car-Parrinello molecular dynamics simulations at ambient conditions for four-, five- and six-coordinated Cu(II) aqua complexes. The molecular geometry has been investigated in terms of Cu-O, Cu-H bond lengths and O-Cu-O bond angles and compared with earlier experimental measurement results and theoretical calculations. We find that the average Cu-O and Cu-H bond lengths increase with increasing coordination number. We have also observed relatively faster structural transition in the case of five- coordinated complex between trigonal bipyramidal and square pyramidal geometry. This result deviates from the findings of the earlier report (A. Pasquarello et al., Science, 2001, 291, 856) on copper( II) in aqueous solution and we attribute these differences to the neglect of solvent environment in our calculations. The averaged absorption spectra for the copper( II) aqua complexes have been computed using spin-restricted density functional linear response formalism taking 100 snap shots from a trajectory of 0.48 ps. We find that the calculated spectra are significantly different, showing clear features that distinguish each coordination model. Comparison with the experimentally reported absorption spectra is made wherever it is possible and the results obtained favor the distorted fivefold-coordination arrangement for the molecular structure of the Cu(II) ion in aqueous solution.

Keyword
MOLECULAR-DYNAMICS SIMULATION; DENSITY-FUNCTIONAL THEORY; GAUSSIAN-BASIS SETS; COPPER CENTERS; SPECTROSCOPIC PROPERTIES; ELECTRONIC-STRUCTURE; HYDRATED IONS; ATOMS LI; CU2+; SOLVATION
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-8424 (URN)10.1039/b806423g (DOI)000262007000008 ()2-s2.0-58149174187 (Scopus ID)
Note

QC 20100714. Uppdaterad från submitted till published (20100714).

Available from: 2008-05-12 Created: 2008-05-12 Last updated: 2017-12-14Bibliographically approved
3. Modelling the visible absorption spectra of copper(II) acetylacetonate by density functional theory
Open this publication in new window or tab >>Modelling the visible absorption spectra of copper(II) acetylacetonate by density functional theory
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2010 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 492, no 1-3, 14-18 p.Article in journal (Refereed) Published
Abstract [en]

Spin restricted open-shell Density Functional Theory calculations have been carried out by means of linear response theory to investigate the visible absorption spectrum of copper(II) acetylacetonate complex, Cu(acac)(2). The 3d -> 3d transition energies and the influence of molecular structure and non-coordinating solvent on the spectra have been investigated. The obtained four 3d -> 3d transition energies accord well with the experimental data in the crystal phase. The presented results indicate that the experimentally observed four band structure of Cu(acac)(2) is of molecular nature, and not caused by factor-group splitting in the crystal environment as previously suggested.

Keyword
ELECTRONIC ABSORPTION; RESONANCE RAMAN; BASIS-SET; COMPLEXES; PROTEIN; EXCHANGE; PLANAR
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-8425 (URN)10.1016/j.cplett.2010.04.022 (DOI)000277717300003 ()2-s2.0-77953291481 (Scopus ID)
Note
QC 20100714. Uppdaterad från manuskript till artikel (20100714).Available from: 2008-05-12 Created: 2008-05-12 Last updated: 2017-12-14Bibliographically approved
4. Theoretical study of specific solvent effects on the optical and magnetic properties of copper(II) acetylacetonate
Open this publication in new window or tab >>Theoretical study of specific solvent effects on the optical and magnetic properties of copper(II) acetylacetonate
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(English)Manuscript (Other academic)
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-8426 (URN)
Note
QC 20100714 Manuskriptet har uppdaterats och publicerats som "Theoretical Study of Specific Solvent Effects on the Optical and Magnetic Properties of Copper(II) Acetylacetonate". Available from: 2008-05-12 Created: 2008-05-12 Last updated: 2011-03-18Bibliographically approved
5. Density functional restricted-unrestricted approach for nonlinear properties: Application to electron paramagnetic resonance parameters of square planar copper complexes
Open this publication in new window or tab >>Density functional restricted-unrestricted approach for nonlinear properties: Application to electron paramagnetic resonance parameters of square planar copper complexes
2008 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 129, no 6, 064109-1-064109-17 p.Article in journal (Refereed) Published
Abstract [en]

The density functional restricted-unrestricted approach for treatments of spin polarization effects in molecular properties using spin restricted Kohn-Sham theory has been extended from linear to nonlinear properties. It is shown that the spin polarization contribution to a nonlinear property has the form of a quadratic response function that includes the zero-order Kohn-Sham operator, in analogy to the lower order case where the spin polarization correction to an expectation value has the form of a linear response function. The developed approach is used to formulate new schemes for computation of electronic g-tensors and hyperfine coupling constants, which include spin polarization effects within the framework of spin restricted Kohn-Sham theory. The proposed computational schemes are in the present work employed to study the spin polarization effects on electron paramagnetic resonance spin Hamiltonian parameters of square planar copper complexes. The obtained results indicate that spin polarization gives rise to sizable contributions to the hyperfine coupling tensor of copper in all investigated complexes, while the electronic g-tensors of these complexes are only marginally affected by spin polarization and other factors, such as choice of exchange-correlation functional or molecular structures, will have more pronounced impact on the accuracy of the results.

Keyword
TRANSITION-METAL-COMPLEXES; HYPERFINE COUPLING-CONSTANTS; SPIN-ORBIT OPERATORS; KOHN-SHAM THEORY; CRYSTAL-STRUCTURE; HARTREE-FOCK; G-TENSORS; CORRELATION-ENERGY; EPR PARAMETERS; EXCHANGE
National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-8427 (URN)10.1063/1.2964102 (DOI)000258490600010 ()2-s2.0-49749116813 (Scopus ID)
Note
QC 20100714. Uppdaterad från submitted till published (20100714).Available from: 2008-05-12 Created: 2008-05-12 Last updated: 2017-12-14Bibliographically approved
6. Degenerate perturbation theory for electronic g tensors: leading-order relativistic effects
Open this publication in new window or tab >>Degenerate perturbation theory for electronic g tensors: leading-order relativistic effects
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2008 (English)In: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 4, no 11, 1810-1828 p.Article in journal (Refereed) Published
Abstract [en]

A new approach for the evaluation of the leading-order relativistic corrections to the electronic g tensors of molecules with a doublet ground state is presented. The methodology is based on degenerate perturbation theory and includes all relevant contributions to the g tensor shift up to order theta(alpha(4)) originating from the one-electron part of the Breit-Pauli Hamiltonian-that is, it allows for the treatment of scalar relativistic, spin-orbit, and mixed corrections to the spin and orbital Zeeman effects. This approach has been implemented in the framework of spin-restricted density functional theory and is in the present paper, as a first illustration of the theory, applied to study relativistic effects on electronic g tensors of dihalogen anion radicals X-2(-) (X = F, Cl, Br, I). The results indicate that the spin-orbit interaction is responsible for the large parallel component of the g tensor shift of Br-2(-) and I-2(-), and furthermore that both the leading-order scalar relativistic and spin-orbit corrections are of minor importance for the perpendicular component of the g tensor in these molecules since they effectively cancel each other. In addition to investigating the g tensors of dihalogen anion radicals, we also critically examine the importance of various relativistic corrections to the electronic g tensor of linear molecules with Sigma-type ground states and present a two-state model suitable for an approximate estimation of the g tensor in such molecules.

Keyword
DENSITY-FUNCTIONAL CALCULATIONS; TRANSITION-METAL-COMPLEXES; PARAMAGNETIC MOLYBDENUM COMPLEXES; SPIN-ORBIT OPERATORS; RESONANCE PARAMETERS; MAGNETIC-PROPERTIES; RESPONSE THEORY; HARTREE-FOCK; G-VALUES; EPR
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-8428 (URN)10.1021/ct800053f (DOI)000260851300002 ()2-s2.0-58149214184 (Scopus ID)
Note
QC 20100714. Uppdaterad från submitted till published (20100714).Available from: 2008-05-12 Created: 2008-05-12 Last updated: 2017-12-14Bibliographically approved

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Citation style
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Output format
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