Synthesis, structure, physico-chemical properties and biological activity of copper(II) ketoiminate complexes derived from N-naphthyl- and N-quinolyl-β-aminovinyl ketones

Abstract

Four novel copper(II) complexes of N-quinolyl or N-naphthyl substituted β-aminovinyl ketones, derivatives of either benzoylacetaldehyde or benzoylacetone were synthesized. Their structures and physico-chemical properties were studied using single-crystal XRD analysis, XANES and EXAFS, IR, EPR, and UV–Vis spectroscopy, magnetic measurements, and DFT calculations. All investigated metal chelates have the ML2 composition. The square-planar coordination geometry in the N-naphthyl substituted copper(II) ketoiminate complexes is formed by bidentate NO coordination of the deprotonated β-aminovinyl ketones. Both copper(II) N-quinolyl substituted ketoiminate complexes have square-pyramidal coordination geometry with one of two deprotonated β-aminovinyl ketone ligands coordinated as NNO tridentate. In the copper(II) complex of N-quinolyl substituted β-aminovinyl ketone derived from benzoylacetaldehyde, the remaining coordination sites are occupied with the enamine and quinoline nitrogen atoms of the second ligand. On the other hand, in the copper(II) complex prepared from its β-methyl derivative the second ligand coordinates through the azomethine nitrogen and the enamine ketone oxygen. Antibacterial, antifungal, and protistocidal activity of compounds was tested. The β-methyl substituted N-quinolyl-β-aminovinyl ketone and its copper(II) complex exhibit the most pronounced biological activity.