Synthesis, crystal structures and characterizations of three new copper(II) complexes including anti-inflammatory diclofenac

Abstract

Three new diclofenac-based copper(II) complexes, namely tetrakis{μ-2-[2-(2,6-dichloroanilino)phenyl]acetato-κ2 O:O′}bis(methanol-κO)copper(II), [Cu2(μ-dicl)4(CH3OH)2] (1), bis{2-[2-(2,6-dichloroanilino)phenyl]acetato-κ2 O,O′}bis(1-vinyl-1H-imidazole-κN 3)copper(II), [Cu(dicl)2(vim)2] (2), and bis{2-[2-(2,6-dichloroanilino)phenyl]acetato-κ2 O,O′}bis(1H-imidazole-κN 3)copper(II), [Cu(dicl)2(im)2] (3) [dicl is diclofenac (C14H10Cl2NO2), vim is 1-vinylimidazole (C5H6N2) and im is imidazole (C3H4N2)], have been synthesized and characterized by elemental analysis, FT–IR spectroscopy, thermal analysis and single-crystal X-ray diffraction. X-ray diffraction analysis shows that complex 1 consists of dimeric units in which the dicl ligand exhibits a bidentate syn,syn-μ2 coordination mode linking two copper(II) centres. Complexes 2 and 3 have mononuclear units with the general formula [Cu(dicl)2 L 2] (L is vim or im) in which the CuII ions are octahedrally coordinated by two L and two dicl chelating ligands. The L and dicl ligands both occupy the trans positions of the coordination octahedron. The different coordination modes of dicl in the title complexes were revealed by Fourier transform IR (FT–IR) spectroscopy. The spin matching between the copper(II) centres in the dimeric [Cu2(μ-dicl)4(CH3OH)2] units was also confirmed by magnetic data to be lower than the spin-only value and electron paramagnetic resonance (EPR) spectra. The thermal properties of the complexes were investigated by thermogravimetric (TG) and differential thermal analysis (DTA) techniques.