Solvolysis and cytotoxicity of dinuclear ruthenium(II)-2,2′-bipyridine complexes with various bridged-ligands

In order to reveal the solvolysis reactions of dinuclear ruthenium(II)-2,2′-bipyridine complexes with various bridged-ligands (BL), [{RuCl(bpy)2}2(μ-BL)]2+ ([Ru2Cl2-BL]2+), we have studied the kinetics of these complexes in H2O and H2O–dmso (1:1 v/v). In H2O–dmso (1:1 v/v), time-course UV–Vis absorption and IR spectra indicate that the labile Cl− ligands of [Ru2Cl2-BL]2+ are successively substituted by H2O followed by dmso, [{Ru(dmso-S)(bpy)2}2(μ-BL)]4+. Cytotoxicity assays of dinuclear ruthenium(II) complexes were performed in L1210 murine leukemia cell line. [Ru2Cl2-BL]2+ complexes exhibit much lower cytotoxicity compare to cisplatin. However, [{Ru(dmso-S)(bpy)2}2(μ-BL)]4+ complexes produced in H2O–dmso are found to much more cytotoxic than [Ru2Cl2-BL]2+ and in particular the cytotoxicity of [{Ru(dmso-S)(bpy)2}2(μ-dado)]4+ (dado = 1,12-diaminododecane) is comparable to that of cisplatin.

The UV–Vis spectra of [Ru2Cl2-dado]2+ in H2O–dmso (1:1 v/v) result in dramatic changes. [Ru2Cl2-BL]2+ complexes exhibit much lower cytotoxicity compare to cisplatin. However, [{Ru(dmso-S)(bpy)2}2(μ-BL)]4+ complexes produced in H2O–dmso are found to much more cytotoxic than [Ru2Cl2-BL]2+.Figure optionsDownload as PowerPoint slideHighlights
► The UV–Vis spectra of [Ru2Cl2-BL]2+ in H2O–dmso (1:1 v/v) result in dramatic changes.
► The rate constants for the solvolysis are correlated with the redox potentials.
► The dmso ligand would make significant contributions to the cytotoxicity.