Synthesis, Characterization and Biological Evaluation of NovelMacrocyclic Metal Complexes: Insights from Spectroscopic Analysis, Molecular Docking, Antioxidant Studies, andAntimicrobial Screening

Significant contributions to the development of inorganic chemistry were made by macrocyclic complexes. It has stimulated interest in the study of macrocyclic metal ‎complexes in the design and development of novel antibiotics. In this regard, a series of nine ‎novel macrocyclic complexes of Co(II), Ni(II), and Cu(II) were synthesized by a template approach ‎in a [2:1:2] ratio utilizing o-phenylenediamine and dicarboxylic acid. The newly designed ‎complex's structure has been verified by elemental analysis, Fourier transform infrared, UV-Visible, mass spectrometry, thermogravimetric (TG) analysis, and EPR studies. The Coats-Redfern method was employed for the evaluation of various thermodynamic parameters. Based on ‎the spectral studies distorted octahedral geometry has been proposed around the central metal ion ‎in the synthesized complexes. The synthesized complexes were evaluated against Gram-positive ‎bacteria [S. aureus, B. subtilis] and Gram-negative [E. coli, P. aeruginosa] along with fungal ‎strains [C. albicans and A. niger] to assist their antimicrobial potential by agar well diffusion ‎method. Furthermore, the complexes have also been examined for their antioxidant activity ‎utilizing the DPPH assay. Subsequently, molecular docking studies were performed using the Auto ‎Dock Vina programme to assess the biological significance of the synthesized complexes and ‎determine effective binding modes between different ligands and the receptor proteins. The ‎copper macrocyclic complexes demonstrated excellent biocidal action against the selected ‎microbes. Copper acetate exhibited the highest antioxidant potential. The obtained results revealed ‎that the synthesized macrocyclic complexes are potent for making them attractive metal-based ‎antimicrobial and antioxidant prototypes‎.