Synthesis, Characterisation, and Cytotoxic Activity of New Schiff Base Prepared Using 3,3`-Diamino Benzidine and its Complexes with Cu (II), Co (II), and Ni (II) Against Oesophageal Cancer Cell Line (SK-GT-4)

The chemistry of condensed Schiff base compounds, including their potential for drug development and other biological properties, has been the subject of numerous experiments. Amines are important to medicinal chemistry since they are available as natural compounds and are the building blocks of several currently marketed drugs. This study used the condensation reaction between 3,3'-diaminobenzidine and 2-hydroxy-1-naphthaldehyde to synthesise a new chemical compound (Schiff base). Transition metal complexes containing copper(II) (Cu(II)), cobalt(II) (Co(II)), and nickel(II) (Ni(II)) were then created by reacting the ligand with the respective metal chlorides in a molar ratio of 2:1. A range of spectroscopic and characterisation tests were conducted on the ligand and its metal complexes to confirm their structural geometry. Nuclear magnetic resonance (NMR) tests were performed on the novel ligand as a product using proton NMR (1H-NMR), carbon NMR (13C-NMR), mass spectrometer, ultraviolet-visible (UV-Vis) absorption, infrared (IR) and molecular weight determination, molar conductance, and magnetic measurement techniques. The cytotoxicity of the Schiff base ligand and its complexes against the SK-GT-4 cell line, a model for oesophageal cancer, was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results showed that the Co(II) combination was highly active against the SK-GT-4 cells. Additionally, this substance was evaluated biologically and toxicologically on healthy cells. The complex was notable for its remarkable selectivity, allowing it to efficiently target and eradicate cancer cells while causing the least damage to healthy cells.