EPR Study of 5-Chlorosalicylate-Cu(II)-3-Pyridylmethanol Ternary Complex Systems in Frozen Water–Methanol Solutions

• Published in: Applied magnetic resonance Vol. 39; no. 4; pp. 423 - 435
• Main Authors: Martiška, L., Husáriková, L., Repická, Z., Valigura, D., Valko, M., Mazúr, M.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.12.2010; Springer Nature B.V
• Subjects: Atoms and Molecules in Strong Fields; Biological activity; Complex systems; Copper; Electron paramagnetic resonance; Fine structure; Isotopes; Laser Matter Interaction; Ligands; Methanol; Nitrogen; Nitrogen atoms; Nonsteroidal anti-inflammatory drugs; Organic Chemistry; Physical Chemistry; Physics; Physics and Astronomy; Simulation; Solid State Physics; Spectra; Spectroscopy/Spectrometry; Spectrum analysis; Electron Paramagnetic Resonance Measurement; Freeze Solution; Freeze Water; Electron Paramagnetic Resonance; Electron Paramagnetic Resonance Spectrum
• ISSN: 0937-9347; 1613-7507
• DOI: 10.1007/s00723-010-0178-0

Two copper(II) ternary complex systems containing 5-chlorosalicylic acid (5-ClsalH) and different copper(II) salts with varying 3-pyridylmethanol (ron = ronicol) concentration, system I [CuSO 4 (aq) +2(5-ClsalH(solv)) +  x ron(l)] and system II [Cu(ac) 2 (aq) + 2(5-ClsalH(solv)) +  x ron(l)], where x  = 0, 2, 4, 6 and 8, were prepared and studied by electron paramagnetic resonance (EPR) spectroscopy in frozen water–methanol solutions to observe the effects of different copper(II) salts and varying neutral ligand concentration on the formation of resulting complexes in solution. The trend in g -values ( g ||  >  g ⊥  > 2.0023) indicates that the unpaired electron on the copper ion is localized in the orbital. The detailed analysis of the second-derivative Cu(II) EPR spectra has shown well-resolved 14 N superhyperfine splitting in the perpendicular part of the axially symmetric spectra. The resolution of nitrogen superhyperfine multiplet patterns increased with increase in the ronicol concentration (ligand-to-metal ratio x ). The number of superhyperfine lines was found to be constant (nonet) when x  > 4 for system I and x  ≥ 4 for system II. This fact indicates that for these x -values four equivalent nitrogen atoms could be coordinated to the central copper atom in the equatorial plane of both systems.