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Conformations, structural transitions and visible near-infrared absorption spectra of four-, five- and six-coordinated Cu(II) aqua complexes
KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).ORCID-id: 0000-0003-0185-5724
KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).ORCID-id: 0000-0003-2729-0290
KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).ORCID-id: 0000-0001-8748-3890
Visa övriga samt affilieringar
2009 (Engelska)Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 11, nr 3, s. 508-519Artikel i tidskrift (Refereegranskat) 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.

Ort, förlag, år, upplaga, sidor
2009. Vol. 11, nr 3, s. 508-519
Nyckelord [en]
MOLECULAR-DYNAMICS SIMULATION; DENSITY-FUNCTIONAL THEORY; GAUSSIAN-BASIS SETS; COPPER CENTERS; SPECTROSCOPIC PROPERTIES; ELECTRONIC-STRUCTURE; HYDRATED IONS; ATOMS LI; CU2+; SOLVATION
Nationell ämneskategori
Kemi
Identifikatorer
URN: urn:nbn:se:kth:diva-8424DOI: 10.1039/b806423gISI: 000262007000008Scopus ID: 2-s2.0-58149174187OAI: oai:DiVA.org:kth-8424DiVA, id: diva2:13739
Anmärkning

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

Tillgänglig från: 2008-05-12 Skapad: 2008-05-12 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
Ingår i avhandling
1. Optical and Magnetic Properties of Copper(II) Compounds
Öppna denna publikation i ny flik eller fönster >>Optical and Magnetic Properties of Copper(II) Compounds
2008 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH, 2008. s. vi, 53
Nationell ämneskategori
Industriell bioteknik
Identifikatorer
urn:nbn:se:kth:diva-4743 (URN)978-91-7415-014-8 (ISBN)
Disputation
2008-05-30, FA32, AlbaNova, Roslagstullsbacken, Stockholm, 10:00
Opponent
Handledare
Anmärkning
QC 20100714Tillgänglig från: 2008-05-12 Skapad: 2008-05-12 Senast uppdaterad: 2010-07-14Bibliografiskt granskad

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Natarajan Arul, MuruganHugosson, Håkan WilhelmVahtras, OlavÅgren, Hans

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