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(ηBergamini et al. (2004)⁶-p-cymene)Cl₂}] (3), [C₂₀H₁₆NOS{OPPh₂-Ru(ηBergamini et al. (2004)⁶-benzene)Cl₂}] (4), [C₂₀H₁₆NOS{OPPh₂-Ir(ηGaw 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 Gram-positive 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.