Design, Spectroscopic Characterization, Thermal, 3D Molecular Modeling, XRD and in Vitro Antioxidant and Antimicrobial Screening of Novel N2O2 Tetradentate Schiff’s Base Metal Complexes

Abstract

In the present study, new Co(II), Ni(II) and Cu(II) complexes were synthesized from the reaction of tetradentate Schiff's base ligand (H2L)= (N, N'-(pyridine-2,6-diyl) bis (2-(((Z)-(2-hydroxynaphthalen-1-yl) methylene) amino) benzamide that was synthesized via condensation of 2-amino-N-{2-[(2-amino-benzoylamino) pyridine]-benzamide} with 2-hydroxy-1naphthaldehyde. The ligand and its metal (II) complexes were characterized by microanalyses, magnetic, spectral, powder Xray diffraction (XRD) and thermal studies. An octahedral geometry has been proposed for [Co(L)(H2O)2].3H2O (1), [Ni(L)(H2O)2].1½H2O (2) and square planar for [Cu(L)](3) and [Cu(H2L)(OH)Br](4). EPR spectra of Cu(II) complexes are consistent with dx²-y² ground state. 3D molecular modeling studies have been carried out for ligand and complex (1). Average crystallite size (D) and dislocation density (δ) were calculated from XRD. All compounds were screened for their in vitro antioxidant activity. The results showed that the ligand possesses excellent activity compared to the reference (Ascorbic acid) and complex (4) was the most potent one. Moreover, the current compounds were tested for their antimicrobial activity.