Electrochemistry of different ruthenium polypyridine complexes

Abstract

In search for antitumor metal-based drugs that would mitigate the severe side-effects of cisplatin, Ru(II) complexes are gaining increasing recent interest. Their cytotoxic effect is widely known, however mechanism of action, solution behavior, redox reactions within biological system are still focus of the new studies. Various experiments and approach techniques are used to better understand ruthenium chemistry. In this order their biological activity and the availability of reduction potential in the biological medium, it is necessary to know their electrochemical redox behavior and properties. In this work, we report the electrochemical activity on synthesized and characterized (1H- and 13C NMR, FT-IR, MS) half-sandwich organometallic Ru(II) complexes of the general formula [Ru(η6-arene)(XY)Cl](PF6) where arene = benzene, toluene or p-cymene and XY = bidentates: dipyrido[3,2-a:2′,3′-c]phenazine (dppz derivatives) or 2-(9-anthryl)-1H-imidazo[4,5-f][1,10]phenanthroline (aip), which are bound to Ru(II) via two phenanthroline-N atoms in a characteristic “piano-stool” configuration of Ru(II)-arene complexes – as confirmed by vibrational and NMR spectra. It is shown that selected complexes can be divided in four groups, based on their electrochemical behavior. These behaviors are correlated with their structure and nature of ligands.