Mono and dinuclear ruthenium, rhodium and iridium metal complexes containing N-acylhydrazone moiety: Synthesis and in vitro biological studies

The mono and dinuclear bidentate complexes were obtained by treatment of the hydrazone ligands (L1, L2, L3) with metal precursors [(arene)MCl2]2 (arene = p-cymene, Cp*; M = Ru, Rh and Ir). In dinuclear complexes ligand L3 acts as a tridentate ditopic ligand bridging between two metal centers. [Display omitted] Half-sandwich mono and dinuclear ruthenium, rhodium and iridium complexes (1–9) have been synthesized with ligands L1 {N'-(9H-fluoren-9-ylidene) thiophene-2-carbohydrazide}, L2 {N'-(9H-fluoren-9-ylidene)-3-methoxybenzohydrazide} and L3 {N'-(9H-fluoren-9-ylidene) isonicotinohydrazide}. The neutral mononuclear bidentate complexes were obtained by treatment of the hydrazone ligands (L1, L2) with metal precursors [(arene)MCl2]2 (arene = p-cymene, Cp*; M = Ru, Rh and Ir) in a 1:2 ratio. Reactions of [(arene)MCl2]2 with L3 in both 1:2 and 1:1 metal dimer to ligand ratios have yielded neutral dinuclear complexes where L3 acts as a tridentate ditopic ligand. Single-crystal X-ray diffraction studies have determined the solid-state structures of eight complexes (1–7, 9). In vitro antibacterial activities of the synthesized ligands and complexes were evaluated against human pathogenic bacteria. These compounds were evaluated for their in vitro antioxidant activity by using the DPPH assay. The binding capacity of complex 2 to SM-DNA was elucidated using fluorescence spectroscopy.