Synthesis of ionic liquid-based Ru(II)–phosphinite complexes and evaluation of their antioxidant, antibacterial, DNA-binding, and DNA cleavage activities

Two Ru(II) complexes were synthesized by reaction of phosphinite-functionalized imidazolium salts [(Ph2PO)C7H11N2Cl]Cl (1) and [(Cy2PO)C7H11N2Cl]Cl (2) with 1/2 equivalent of [Ru(η6-p-cymene)(µ-Cl)Cl]2 in anhydrous CH2Cl2 and under argon atmosphere. The complexes were then isolated as analytically pure substances and characterized using multinuclear NMR and infrared spectroscopies and elemental analysis. The Ru(II) compounds were used to study their biological assay. For this purpose, radical scavenging, reducing power, antibacterial activity, DNA binding, and DNA cleavage activity were fully studied. The maximum 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH) scavenging (78.9%) and reducing power were obtained from compound 4 at the concentration of 200 µg/ml. The compounds were also tested against three Gram-positive and three Gram-negative bacteria, and they were found to be more effective against Gram-positive bacteria. In addition, both compounds showed excellent DNA binding and DNA cleavage activity.