3D supramolecular architectures of copper(II) complexes with 6-methylpicolinic and 6-bromopicolinic acid: Synthesis, spectroscopic, thermal and magnetic properties |
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| Authors: | Boris-Marko Kukovec Zora Popovi&#x; Bojan Kozlev
ar Zvonko Jagli
i&#x; |
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| Institution: | aLaboratory of General and Inorganic Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000 Zagreb, Croatia;bFaculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana, Slovenia;cInstitute of Mathematics, Physics and Mechanics, Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia |
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| Abstract: | Copper(II) complexes of 6-methylpicolinic (6-MepicH) and 6-bromopicolinic acid (6-BrpicH), namely Cu(6-Mepic)2(H2O)] (1), Cu(6-Mepic)2(py)] (2) and Cu(6-Brpic)2(H2O)] (3) were prepared and characterized by spectroscopic methods (IR, EPR). Their molecular and crystal structures were determined by X-ray crystal structure analysis, their thermal stability by TGA/DTA methods, while their magnetic properties were elucidated by the measurement of the magnetic susceptibility. X-ray structural analysis revealed an intermediate between square-pyramidal and trigonal-bipyramidal coordination polyhedron in 1 and 3 and a trigonal-bipyramidal one in 2 with the same N,O-chelated coordination mode for both 6-MepicH and 6-BrpicH in 1–3. EPR spectra showed three different types of copper(II) S = ½ symmetry signals. Most probably they could be assigned to the elongated axial in 1, the isotropic in 2 and the rhombic in 3. Both 1 and 2 showed the paramagnetic behaviour, while 3 exhibited an antiferromagnetic interaction, ascribed to the formation of pseudobinuclear units by the π···π stacking between pyridine rings. |
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| Keywords: | Copper(II) complexes Carboxylate ligands π · · · π interactions EPR spectroscopy Magnetic properties Thermal methods (TGA/DTA) |
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