Transition metal (II) complexes of 2-(2,5-dimethoxy-benzylidene)hydrazine-1-carbothioamide: synthesis, characterization and their biological evaluation

The current study involved synthesizing Schiff base ligand, 2-(2,5-dimethoxybenzylidene)hydrazine-1-carbothioamide (L) by combining thiosemicarbazide (Th) with 2,5-dimethoxybenzaldehyde (2,5-Dmb), and synthesizing its novel complexes of Co(II), Ni(II), and Cu(II) ions. Elemental analysis, conductance measurements, magnetic susceptibility, molecular weight estimations, FT-IR, ESI-Mass, and UV-Vis spectrum analysis have confirmed the ligand and its metal complexes. The experiment data demonstrated that the ligand binds to the metal atom in a bidentate manner through the N and S atoms. The cytotoxic activity of the synthesized complexes was tested against brine shrimp. All the complexes showed cytotoxic activity; among them, ligands showed a better result with LC₅₀ value of 36.93 µg/mL than complexes. Using disc diffusion, the antibacterial action was tested against two Gram-positive bacteria and two Gram-negative bacteria. [Ni(L)₂] was more effective against E. coli than the other compounds. The results verified the formation of the novel complexes, and the Ni-complex has the potential to generate novel antibacterial compounds for use in biomedical applications.