Synthesis, characterization of some Cu(II) complexes of 1,2,4-triazine ligands and their evaluation as antimicrobial and antioxidant agent

Abstract

Three Cu(II) complexes of as-triazines; 3-(2-Py)-5,6-diphenyl-1,2,4-triazine (PDT), 3-(2-Py)-5,6-bis-(p-methoxyphenyl)-1,2,4-triazine (PBMPT) and 3-(2-Py)-5,6-bis(4-biphenyl)-1,2,4-triazine (PBBT) have been synthesized and characterized by elemental analysis, complexometric method, thermogravimetric analysis, FTIR, UV–Vis spectroscopy, magnetic susceptibility measurements, scanning electron microscopy, X-ray powder diffraction studies, and conductivity measurements. FTIR spectroscopic data have confirmed the existence of Cu-N and Cu-O bonds in all three complexes as well as stretching frequencies of N = N and C = N complexes have been shifted towards lower frequencies in comparison with that of the ligands. In UV–Vis spectra, a bathochromic shift has been observed for the complexes due to variations in substituents in as-triazine ligands. Molar conductance measurement confirmed the non-electrolytic nature of the complexes. From the values of magnetic moment measurements, it can be concluded that all complexes belong to distorted octahedral geometry, and as-triazines act as a bidentate ligand and coordinate with the metal ion via nitrogen atoms of triazine and pyridine moiety respectively. Since metallotriazine complexes possess interesting biological and medicinal properties; antimicrobial and antioxidant properties of these as-triazine-copper(II) complexes were also studied. The results from antimicrobial studies show that all the complexes and as-triazines except PDT itself possess high antimicrobial activity. All the three synthesized complexes showed significant antioxidant DPPH radical scavenging activity with IC50 values in the range of 20–30 µg/mL.