3D supramolecular architectures of copper(II) complexes with 6-methylpicolinic and 6-bromopicolinic acid: Synthesis, spectroscopic, thermal and magnetic properties

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.

Three copper(II) complexes with 6-methylpicolinic and 6-bromopicolinic acid were prepared and characterized by spectroscopic (IR, EPR), thermal methods (TGA/DTA) and by magnetic susceptibility measurements. Their crystal structures were determined by X-ray structural analysis and their magnetic properties discussed in correlation with the structure.Figure optionsDownload as PowerPoint slide