Dinuclear half-sandwich Ir(III) complexes containing 4,4′-methylenedianiline-based ligands: synthesis, characterization, cytotoxicity

Abstract Three dinuclear half-sandwich iridium(III) complexes [Ir2(μ-L1)(η5-Cp*)2Cl2](PF6)2 (1), [Ir2(μ-L2)(η5-Cp*)2Cl2](PF6)2 (2) and [Ir2(μ-L3)(η5-Cp*)2Cl2](PF6)2 (3) with tetradentate 4,4′-methylenedianiline-based N-donor ligands (L1–L3) were prepared and characterized by NMR spectroscopy, elemental analysis, mass spectrometry and FTIR spectroscopy. Complex 3 was hydrolytically less stable in 20% DMSO-d6/80% D2O than 1 and 2, while all the studied complexes were stable in the same mixture of solvents in the presence of PBS (pH 7.4). In addition, complexes 1–3 converted coenzyme NADH to its oxidized form (NAD+). Cytotoxicity of 1–3 was evaluated on five human cancer cell lines, in particular lung carcinoma (A549), hepatocellular carcinoma (HepG2), melanoma (A375), prostate carcinoma (DU-145) and breast carcinoma (MCF-7). The best-performing complex 2 showed comparable cytotoxicity to conventional cisplatin against the A549 and HepG2 cell lines.