Abstract
Three mononuclear cyclometalated iridium(III) complexes having dithiocarbamate ligands, [IrIII(2-C6H4py)2(L)] (where 2-C6H4py = 2-phenylpyridine; and L1H = 4-MePipzcdtH, L2H = MorphcdtH, and L3H = 4-BzPipercdtH for 1, 2, and 3, respectively), were synthesized from [Ir(2-C6H4py)2Cl]2·1/4CH2Cl2 by displacing the two bridging chlorides with one dithiocarbamate ligand. The complexes were characterized using physicochemical and spectroscopic tools along with structural analysis of [Ir(2-C6H4py)2(L2)] (2) by single crystal X-ray diffraction. Structural analysis of 2 showed a distorted octahedron in which the nitrogen donor of one 2-phenylpyridine and the carbon donor of another 2-phenylpyridine are in axial positions, trans to one another. Electrochemical analysis by cyclic voltammetry showed the irreversible two-electron equivalent reduction voltammograms of 1, 2, and 3 attributable to Ir(III) to Ir(I). Electronic characterizations of these complexes are consistent with significant delocalization of the sulfur electron density onto the empty metal d-orbital. The intercalative interaction of the complexes with calf thymus DNA was evaluated using absorption, fluorescence quenching, and viscosity measurements. The binding affinities of these complexes with bovine serum albumin were estimated in terms of quenching constants using the Stern–Volmer equation. Study of antibacterial activities of the complexes by agar disk diffusion against some species of pathogenic bacteria was also performed.
Graphical Abstract
Acknowledgements
Financial support from the Council of Scientific and Industrial Research (CSIR), New Delhi, India is gratefully acknowledged.