Three ruthenium(II) polypyridyl complexes, [Ru(phen)(mip)](ClO) (1) (phen =1,10-Phenanthroline), [Ru(bpy)(mip)](ClO) (2) (bpy = 2,2'bipyridyl) and [Ru(dmb)(mip)](ClO) (3) (dmb = 4, 4'-dimethyl 2, 2'-bipyridine), were synthesized with an intercalative ligand mip (2-morpholino-1H-imidazo[4,5-f][1, 10]phenanthroline) and characterized by H,C-NMR, IR, UV-vis, mass spectra and elemental analysis. pH effect, ion selectivity (cations, anions) and solvent sensitivity of complexes were studied. The interaction of these complexes with DNA was performed using absorption, emission spectroscopy and viscosity measurements. The experimental results indicated that the two complexes interacted with calf thymus DNA (CT-DNA) by intercalative mode. BSA (Bovine Serum Albumin) protein binding of these complexes was studied by UV-visible and fluorescence techniques. The binding capacity of these complexes was explained theoretically by molecular docking method.

Graphical representation of Ru(ii) complexes causing cell death.

A set of novel mononuclear polypyridyl complexes of Ru (II) with N – N donar ligands 1, 10 phenanthroline (phen), 2, 2′ bipyridine (bpy), 4, 4′‐dimethyl 2, 2′ bipyridine (dmb) and an intercalating ligand (bnpip = 2‐(4‐butoxy‐3‐nitrophenyl)‐1H‐imidazo [4,5‐f] [1,10] phenanthroline) have been synthesized and characterized by various spectral methods. The RT ‐ PCR assays suggest that ruthenium (II) complexes inhibit MCF‐7, breast cancer cell line by inducing apoptosis via inhibition of cell cycle check points cyclin D, cyclin E and also upregulation of caspase 8 (protein involved in late Apoptosis). Further the binding potency of Ru (II) complexes were investigated using various spectroscopic techniques like UV–visible, fluorescence and viscosity studies. The complex binds to DNA in an intercalative mode as confirmed by viscosity data with differential binding strength. All complexes show cleavage of the pBR322 DNA through a singlet oxygen production. Theoretical evidence via docking of the complex with DNA reveals the significant residues of binding as guanine.

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