Some New Zinc Halide Complexes of N₂O₂-Schiff Base: Synthesis, Thermal, Antimicrobial, Antioxidant, Anticancer and...

A series of novel zinc(II) complexes derived from a tetradentate N₂O₂-Schiff base ligand were synthesized using zinc halide and pseudohalide salts with the general formula ZnLX₂ (X = Cl^-, Br^-, I^-, N₃ ^-, SCN^-). The resulting compounds were thoroughly characterized by a range of spectroscopic and physicochemical techniques. Additionally, nanostructured zinc complexes such as ZnLBr₂ and ZnLI₂ were synthesized via an ultrasound-assisted approach, with ZnLI₂ subsequently utilized as a precursor for the fabrication of ZnO nanoparticles. The nanostructures were confirmed by scanning electron microscopy (SEM), EDX, and x-ray diffraction (XRD) analyses. Thermal decomposition studies of the ligand and its zinc complexes revealed two- to three-step degradation processes, for which key thermokinetic parameters (E*, ΔS*, ΔH*, A, and ΔG*) were determined. From a biological standpoint, the synthesized compounds displayed potent antimicrobial activity against selected Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacterial strains, as well as fungal pathogens (Aspergillus oryzae and Candida albicans). DNA cleavage assays further confirmed the nucleolytic potential of these complexes. Selected compounds demonstrated noteworthy cytotoxic effects against the PC3 human prostate cancer cell line, substantiating their anticancer capabilities. Antioxidant properties were evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays, exhibiting promising radical-scavenging activity. Notably, the ligand and ZnLI₂ complex also exhibited significant efficacy in promoting burn wound healing, highlighting their therapeutic potential in both infectious and regenerative medicine.