Synthesis and Biological Activity of the New Pincer Type Ruthenium(iii) Complex

Abstract

We synthesized and characterized the ruthenium(III) pincer-type complex [RuCl3(H2Lt-Bu] (H2Lt- Bu = 2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine, 1) by elemental analysis, IR and UV-Vis spectroscopy, and mass spectrometry (MS) method ESI Q-TOF. For comparison reason, we also studied ruthenium(III) terpyridine complexes of the general formula [Ru(N-N-N)Cl3] where N-N-N = 4′-chloro- terpyridine (Cl-tpy; 2) or 4′-chlorophenyl-terpyridine (Cl-Ph-tpy; 3). Kinetic study of the substitution reactions of 1–3 with biomolecules showed that the rate constants depend on the properties of the spectator ligand and the nature of the entering nucleophile. To gain further insight into the reactivity of ruthenium complexes with potential biological targets, we examined the interactions of 1 – 3 with DNA and HSA. The DNA/HSA binding study showed that in comparison to complex 1 (bis– pyrazolylpyridine), the other two (2 and 3) terpyridine complexes had a slightly better binding affinity to calf thymus DNA (CT DNA), while in the case of human serum albumin (HSA), complex 1 exhibited the most strong quenching ability.