Catalytic and Antitubercular Activities of Multifunctional Copper(II)-Schiff Base Complexes: Insights into Structure, Theoretical Calculations, and Physicochemical Behavior

Three copper(II) complexes featuring tridentate ONO donor Schiff base ligands were synthesized and thoroughly characterized by X-ray crystallography, spectroscopy, and electrochemical methods. Density functional theory (DFT) calculations provided insights into their electronic structures and ligand-metal interactions. Complex 1 exhibited moderate catalytic activity toward the selective oxidation of toluene and styrene under mild conditions. Biological assays demonstrated measurable antimycobacterial effects against drug-sensitive and -resistant Mycobacterium tuberculosis strains, while combination studies with standard anti-TB drugs revealed mainly additive or indifferent interactions. These results highlight the promise of these copper(II) Schiff-base complexes as multifunctional agents with catalytic and therapeutic applications.