Synthesis, spectral studies and antimicrobial screening of metal complexes of Schiff base derived from substituted salicylaldehyde and 2-amino-6-chloro benzothiazole

Abstract

In the present work Schiff base ligand of benzaldehyde derivative and benzothiazole derivatives was prepared by condensation of 2-amino-6-chloro benzothiazoles and 2, 4-dihydroxybenzaldehyde in a 1:1 molar ratio. It was further treated with bivalent metal salts, resulting in a series of transition metal complexes of the type [M(CBTIHB)₂] [M = Fe, Cu, Co, Ni, Pd, Zn, Hg, and Cd]. The prepared Schiff base HCBTIHB ligand and its bivalent metal complexes were studied using different spectroscopic techniques (¹H NMR, FT-IR, UV) and physicochemical methods. By using the disc diffusion method, two Gram-positive bacterial strains (B. subtilis and S. aureus) and two Gram-negative bacterial strains (E. coli and P. aeruginosa), as well as two fungal strains (C. albicans and A. cerevisiae) were used to test all of the synthesized compounds for antibacterial and antifungal activity in vitro. The spectrum data showed the complexes were hexacoordinated with tridentate ligands, coordinated through oxygen, sulphur, and nitrogen. The XRD data has been analyzed using the advanced Professional program. Particle size, crystal system, lattice parameter, and lattice type had all been approximated from the experimental data. The particle size was measured on the nanoscale scale. All of the complexes were found to be crystalline after being subjected to XRD examination. The results of antimicrobial activity showed that the synthesized complexes were more effective in Gram-positive bacterial strains than in Gram-negative bacterial strains. The in vitro cytotoxicity effects of the ligand and its metal complexes against Artemia salina were also investigated using the brine shrimp bioassay. The results demonstrated that biological activities of the ligand were enhanced during complexation.