Zinc(II) Complexes with Benzothiazolyl Azo Compounds: Synthesis, Structural Characterization, NIR Emission, and Biological Properties

Abstract: Heterocyclic ligands and their metal complexes have received much attention from biochemists due to their potential bioactivities and wide applications in medicinal chemistry. In this study, four benzothiazolyl azo ligands and their zinc(II) azo complexes were synthesized and characterized by various spectroscopic techniques, such as mass spectroscopy, FTIR, NMR, and UV-vis. Their photophysical properties were studied by electronic and luminescent spectra. These zinc(II) complexes exhibited near-infrared emission at 690–900 nm precisely. Based on the received spectral data, a distorted tetrahedral geometry was suggested for all the zinc(II) azo complexes. The antimicrobial activity of the obtained azo compounds was estimated against gram-positive bacteria. All the zinc(II) chelates exhibited effective activity against S. aureus. The cytotoxic ability of the prepared azo compounds was evaluated against human cancer cell lines, i.e., hepatic cancer cells (HepG-2) and lung carcinoma cells (A549). The observed cytotoxic data showed that all prepared azo compounds exhibited a promising antitumor activity against the studied cancer cells with their IC50 values < 50 μg/mL. The benzothiazolyl azo ligands were observed to have a better antitumor potential for HepG2 than A549, while their zinc(II) azo complexes exhibited a better activity for A549 than HepG2. result: These zinc(II) complexes have possessed the near infrared emission at 690 – 900 nm preciously. All the zinc(II) chelates exhibited effective activity against S. aureus. The observed cytotoxic data showed that all prepared azo compounds exhibited a promising antitumor activity against studied cancer cells with IC50 < 50 µg/mL.