A new cytosine-copper paramagnetic complex spectroscopic study

Krilov, Dubravka and Gomzi, Vjeran and Herak, Janko N. (2008) A new cytosine-copper paramagnetic complex spectroscopic study. Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 70 (5). pp. 1238-1242. ISSN 1386-1425

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Official URL: http://doi.org/10.1016/j.saa.2008.01.013

Abstract

Two different copper complexes with cytosine molecules are formed in the process of crystal growth from the aqueous solution with traces of copper. One of them is diamagnetic, turning into paramagnetic upon ionizing irradiation (complex I). The other, the subject of the present study, is paramagnetic (complex II) as prepared. For complex II, EPR spectra demonstrate that the copper ion is coordinated with one nitrogen atom and three oxygen atoms. On the basis of the detailed EPR spectroscopic analysis and quantum-chemical calculations (in the DFT approach) the model of the complex has been proposed. Both experimental data and the theoretical results support the model with the copper atom, located between the two cytosine ribbons, ligated to a nitrogen and an oxygen atom from two opposing cytosine molecules and two oxygen atoms from water molecules. For complex II the Raman spectra demonstrated concerted restructuring of the hydrogen bonding in the cytosine crystal matrix upon insertion of copper ions.

Item Type:

Article

MeSH:

Copper - chemistry ; Cytosine - chemistry ; Electron Spin Resonance Spectroscopy ; Models, Molecular ; Molecular Conformation ; Spectrophotometry, Infrared

Departments:

Katedra za fiziku i biofiziku

Depositing User:

Boris Čičovački

Status:

Published

Creators: