Synthesis of new generation amido-Phosphinite derivative complexes by microwave method and investigation of their biological activities

Several biological activities such as antioxidant, antibacterial, and DNA binding of ruthenium, iridium, and rhodium complexes of a phosphinite were investigated. For this purpose, firstly, a new amide was synthesized from the reaction of 2-(phenylthio)aniline with DL-mandelic acid in a solvent-free environment using microwave irradiation. Subsequently, this amide was converted to its phosphinite counterpart. Then, Ru(II), Ir(III), and Rh(I) complexes (3-6) of the phosphinite were synthesized and characterized by several techniques such as microanalysis, IR, and NMR spectroscopy, and in the case of 4 by single crystal X-ray crystallography. Finally, antioxidant, antimicrobial, and DNA binding activities of [C20H16NOS{OPPh2-Ru(eta Bergamini et al. (2004)6-pcymene)Cl2}] (3), [C20H16NOS{OPPh2-Ru(eta Bergamini et al. (2004)6-benzene)Cl2}] (4), [C20H16NOS{OPPh2-Ir (eta Gaw et al. (2002)5-C5Me5)Cl2}] (5), and [C20H16NOS{OPPh2-Rh(cod)Cl}] (6) complexes were tested. To determine antioxidant activities of the complexes, DPPH (2,2-diphenyl-1-picryl hydrazyl) free radical scavenging, metal chelation, and reducing power activities were measured. At 200.0 mgL-1 concentration, complex 4 showed the highest radical scavenging (74.53 +/- 1.76 %) and metal chelating activity (63.91 +/- 1.54 %), while complex 3 exhibited the highest reducing power activity. Antibacterial activity of the compounds was determined with four pathogenic bacteria. Only ruthenium complexes 3 and 4 had weak activity against two Grampositive bacteria, while the other complexes (5 and 6) did not show any antibacterial activity. Electrophoresis results using calf thymus DNA (CT-DNA) displayed that all complexes had DNA binding activity at different rates.