Synthesis, structural characterization and biological applications of mono- and binuclear Cu(II) and Ni(II) complexes with N2O2 Schiff bases.

[Display omitted] • Schiff bases are suitable for synthesizing of coordination complexes. • Schiff base complexes are used in pharmaceutical industries as drugs. • Environmental issues can be overcome by essential elements like Cu(II) and Ni(II) • Mononuclear complexes serve as ligands for synthetic polynuclear metal complexes. • Metal complexes exhibit square planar geometry and thermodynamic stability. The present work aims to synthesize and characterize new Schiff base metal complexes (Cu(II) and Ni(II)) derived from 4,5-Dichloro- o -phenylenediamine and 3,5-Dichloro-2-hydroxyacetophenone. The synthesized Schiff base and their complexes have been characterized with the support of more than a few standard physicochemical techniques such as elemental analysis, spectroscopic, thermal, and cyclic voltammetry studies. Further the molecular structures are ascertained by computational methods like density functional theory (DFT) methods. The newly synthesized Schiff base ligand acts as ONNO donor tetradentate chelate and coordinated through an azomethine nitrogen and phenoxo oxygen atom to the Cu(II) and Ni(II). Moreover, all the newly prepared compounds exhibit moderate biological activity such as antibacterial. The synthesized compounds were screened for their antibacterial by the disc agar diffusion method. Spectral analysis exhibits square planar geometry for Cu(II) & Ni(II) mono and binuclear complexes. The antimicrobial results indicate that the homo binuclear copper (II) complex was more active than the other mono and binuclear complexes. The theoretical DFT calculations were applied to verify the molecular geometry of chelators and their complexes. The DFT optimized geometries of the complexes are in agreement with experimental observations. [ABSTRACT FROM AUTHOR]