Ruthenium, rhodium, and iridium complexes featuring coumarin hydrazone derivatives: Synthesis, characterization, and preliminary investigation of their anticancer and antibacterial activity

Abstract

Coumarin hydrazone derivatives (L1, L2, L3, and L4) have been prepared by Knoevenagel condensation. Half‐sandwich ruthenium, rhodium, and iridium complexes containing these coumarin hydrazone derivatives (1–12) have been synthesized. The deprotonation of hydrazinic proton from the ligand leads to the formation of anionic species, thereby forming neutral N ∩ N chelation complexes. These complexes have been confirmed by spectroscopic technique and single‐crystal X‐ray diffraction studies. Spectroscopic analysis of the ligands and complexes shows that the data are consistent with the formulated data. The stability studies of some of the complexes (1, 5, and 6) were performed by the 1H‐NMR technique using deuterated DMSO‐d6 solvent. They are found to be stable in solution as well as in the air and are nonhygroscopic. In vitro antibacterial activity against gram‐positive Staphylococcus aureus and gram‐negative Escherichia coli, Klebsiella pneumoniae strains have been tested. Also, their cytotoxicity study was evaluated against Dalton's ascites lymphoma (DL), Ehrlich ascites carcinoma (EAC), and normal cell lines (peripheral blood mononuclear cells [PBMC]). In both the studies, complexes (5 and 6) are found to be the most active compared to the other complexes.