Macrocyclic ligands (MacL1-MacL3) and Co(II) complexes were synthesized via template condensation of o-phenylenediamine with various aromatic dicarboxylic acids. The elemental analysis, FT-IR, mass spectrometry, 1H NMR, 13C NMR, UV-vis, SEM analysis, powder X-ray diffraction, thermogravimetric (TG) analysis, electrochemical studies, and DFT analysis were used to characterize these synthesized ligands and their cobalt (II) complexes. TGA analysis to determine the stability and decomposition kinetic parameters. In element analysis, the percentage of different elements present and also the stoichiometry of compounds were confirmed. The proposed framework for tetraaza macrocyclic cobalt (II) complexes was supported by spectral analysis, which also revealed distorted octahedral geometry surrounding the central metal atom. The molecular structure of cobalt (II) complexes was also optimized theoretically, and their electronic or thermodynamic parameters were obtained from density functional theory (DFT). The synthesized ligands and their cobalt (II) complexes were tested against bacteria: Escherichia coli, Bacillus subtitles. Candida albicans were tested for antifungal properties. It was found that ligands and complexes show good antimicrobial results. Finally, using the Auto Dock VinaPyRx programme, molecular docking studies were used to evaluate the biological significance of the synthesized ligands to identify the probable and efficient binding mechanisms between the various ligands and the active site of the receptor protein.
