3-acetyl-coumarin-substituted thiosemicarbazones and their ruthenium, rhodium and iridium metal complexes: An investigation of the antibacterial, antioxidant and cytotoxicity activities

A series of ruthenium, iridium and rhodium half-sandwich complexes containing 3-acetyl chromen-2-one-4(N)-substituted thiosemicarbazone derivatives have been prepared for use as antibacterial and anticancer agents. These complexes have been isolated as cationic bidentate (N, S) and neutral bidentate (N, S) complexes. The complexes have been characterized by spectral techniques (FT-IR, UV-Vis, NMR and HRMS) and single-crystal X-ray crystallography methods. The structure of complex 6 has been determined by a single-crystal X-ray diffraction study, which shows that coordination of the 3-acetyl chromen-2-one-4(N)-substituted thiosemicarbazone ligand to the metal occurs via azomethine nitrogen and thiolate sulfur atoms. Vitro antibacterial activity against gram-positive Staphylococcus aureus and gram-negative Escherichia coli, Klebsiella pneumonia strains and antioxidant activity have been evaluated. Also, the said complexes were tested for anticancer efficacy (in vitro for 48h) in Dalton's lymphoma (DL) cancer cell lines using cell cytotoxicity (MTT) and apoptosis tests. The results were compared with cisplatin (standard drug) under identical experimental conditions. The cell cytotoxicity results showed that complex 5 induced higher cytotoxicity in DL cells, followed by complex 4, 1, and 2.