Study of versatile coordination modes, antibacterial and radical scavenging activities of arene ruthenium, rhodium and iridium complexes containing fluorenone based thiosemicarbazones

Halide-bridged metal precursors [(arene)MCl2](2) (arene = p-cymene, Cp*; M = Ru, Rh and Ir) on reaction with thiosemicarbazone derivative ligands (L1, L2 and L3) yielded a series of mononuclear ruthenium, rhodium and iridium complexes and their corresponding dinuclear analogues. All these complexes (1-9) were characterized by analytical and spectroscopic techniques. Single-crystal X-ray diffraction studies determined the molecular structures of complexes 1, 5, 7-9. The compounds were screened for their in vitro antibacterial activity against gram-positive Staphylococcus aureus (MTCC 3160, MMSA, ESKAPE) and Bacillus thuringiensis (MTCC 8995) and gram-negative Escherichia coli (MTCC 1687) and Pseudomonas aeruginosa (MTCC 1688, ESKAPE) strains, where they exhibit the significant antibacterial effect. In addition, the compounds were also investigated for antioxidant activities using DPPH radical scavenging assays, in which most of them displayed substantial antioxidant activities. Furthermore, the binding of ligand L3 with biomolecules such as Salmon milt DNA (SM-DNA) investigated by UV-Vis absorption spectroscopy revealed an intercalative mode of interaction. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Metal complexes were synthesized using thiosemicarbazone derivative ligands and halide-bridged metal precursors, showing significant antibacterial and antioxidant activities. The molecular structures were determined, and the binding of ligands with biomolecules was investigated, providing insights into their mechanisms of action.