Di-2-pyridylketone-N1-substituted thiosemicarbazone derivatives of copper(II): Biosafe antimicrobial potential and high anticancer activity against immortalized L6 rat skeletal muscle cells

Abstract The basic aim of this study pertains to developing antimicrobial or anticancer agents based on N, S-donor organic ligands bonded to metals. In the present investigation, di-2-pyridylketone-N1-substituted thiosemicarbazone (py2tscH-N1HR2, Chart 2) thio-ligands were reacted with copper(I) halides in organic solvents yielding copper(II) complexes of stoichiometry, [Cu(N,N,S-py2tsc-N1HR2)X] (X = I, R2 = H, 1; Me, 2; Et, 3; Ph, 4; X = Br, R2 = H, 5; Me, 6; Et, 7; Ph, 8; X = Cl, R2 = H, 9; Me, 10; Et, 11; Ph, 12); the formation of CuII probably occurs through a proton coupled electron transfer (PCET) process. Electron spin resonance, ultraviolet-visible spectroscopy and X-ray crystallography (2, 3, 5, 7, 11) supported a distorted square planar geometry of these complexes. Moderate to high antimicrobial activities of these complexes against methicillin resistant Staphylococcus aureus, Gram positive bacteria, Staphylococcus aureus and Gram negative bacteria, Klebsiella pneumoniae 1, Salmonella typhimurium 2 and one yeast Candida albicans were recorded. Complexes were found to be biosafe with 88–91% cellular viability. All complexes have shown high anticancer activity against the immortalized L6 rat skeletal muscle cell line with very low IC50 values.