Syntheses and structural and serum protein protecting activity of ruthenium(ii)–DMSO complexes containing a mercapto ligand

Abstract

Four new ruthenium(II) complexes [Ru(mpt)₂(DMSO)₂] (1), [Ru(mpt)₂(bpy)] (2), [Ru(mpt)₂(phen)] (3) and [Ru(mpt)₂(tptz)] (4) have been synthesized and characterized by elemental analyses, and IR, ¹H and ¹³C NMR, and electronic absorption spectroscopy. The molecular structures of complexes 1, 2 and 4 were determined crystallographically. The coordination geometries around the ruthenium centre in 1, 2 and 4 are distorted octahedral. As with other Ru(II) pharmacological active compounds, the serum protein binding studies were performed using both the N,S′ and N,N′ donor ligands as well as ruthenium(II) complexes 1–4. It was found that binding of the respective complex was more effective as compared to the respective ligand. Among the different ligands, the order of binding has been evaluated in the order tptz > mpt > phen > Bpy whereas a different order was observed in the respective complexes (4 > 3 > 2 > 1). The binding with tptz and complex 4 was 80% and 84%, respectively. The tptz ligand as well as complex 4 showed hydrophobic interactions which play an important role when interacting with BSA. They possess effective serum protein binding potential within the desired pharmakinetic behavior of good drugs.