Multi-biological activity evaluation of Sn(П), Zn(П) and Fe(П) complexes based on thiocarbohydrazide schiff bases: synthesis, spectroscopic investigations and fluorescence studies

Two new Schiff base ligands (L1 and L2) were synthesized by condensing thiocarbohydrazide (TCH) with o-anisaldehyde or p-anisaldehyde in ethanol. Their mono- and bi-nuclear complexes with Sn(II), Zn(II), and Fe(II) were prepared for potential fluorescence and biological applications. Characterization was performed using FT-IR, NMR, UV-Vis spectroscopy, mass spectrometry, molar conductance, TGA, X-ray diffraction and SEM. XRD results indicated good crystallinity with crystallite sizes of 20-50 nm. Fluorescent intensity of free TCH ligands increased upon complexation with Sn, Zn, and Fe, suggesting their potential as fluorescence chemosensors. The compounds exhibited variable antimicrobial activities against Staphylococcus aureus, Escherichia coli, and Candida albicans, but lower than commercial drugs. L1Fe and L1Zn enhanced L1's cytotoxicity in four colorectal malignancy cells and L1Zn in skin cancer cells (A375), lung cancer cells (A549), uterine cervix cells (HeLa), and glioblastoma cells (U87). L1Fe showed enhanced activity in mammary adenocarcinoma cells (T47D) and triple-negative breast cancer cells (MDA-MB-231). L2Sn exhibited 70fold increase in L2's DPPH radical scavenging compared to the antioxidant ascorbic acid. L1Zn and L2Zn complexes outperformed indomethacin in reducing inflammation in RAW macrophages, enhancing the nanomolar efficacy of L1 and L2. These complexes have promising utility in cancer diagnosis, monitoring and highly selective duality of anti-inflammatory/cytotoxicity treatments.