A Thiosemicarbazone Schiff Base and Its Titanium(IV) Complexes: Spectral Analysis, DFT Studies, and Biological Evaluation.

A new Schiff base (SB) ligand 2-(1-(4-((4-methyl-3H-benzo[b][1,4]diazepin-2-yl)oxy)phenyl)ethylidene)hydrazine-1-carbothioamide (L) was prepared through a condensation reaction of 4-(4-methylbenzo[b][1,4]diazepin-2-yloxy)acetophenone with thiosemicarbazide. The nature of bonding and the stereochemistry of the Ti metal complexes have been elucidated by elemental analysis, IR, 1H NMR, 13C NMR, and mass spectrometry. From IR spectra, it has been observed that the ligand is a neutral bidentate that coordinates to the metal ions through azomethine nitrogen, and the sulfur atom of the thiocarbonyl group. The synthesized ligand and its complexes were screened for antibacterial activities against Escherichia coli (E. coli), Staphylococcus aureus, Extended Spectrum β-Lactamase (ESBL), Methicillin-resistant Staphylococcus aureus (MRSA), and Mycobacterium tuberculosis bacteria (M. tuberculosis). Antifungal activities were performed against Aspergillus fumigatus (A. fumigatus) and Candida albicans (C. albicans). The Ti metal complexes exhibit markedly good biological activities compared to the free ligand, with the highest inhibition against Mycobacterium tuberculosis. Density functional theory (DFT) computations were performed to analyze the electronic structure, stability, and to support the interpretation of the experimental spectroscopic data. These comprehensive findings suggest that the synthesized Schiff base metal complexes are promising candidate for antimicrobial therapeutic applications.