Synthesis, structural characterization and antimicrobial activity of Schiff bases and benzimidazole derivatives and their complexes with CoCl2, PdCl2, CuCl2 and ZnCl2

Abstract

In this study, new Schiff bases (H2L1 and H2L2) and benzimidazolylphenol derivatives (HL3 - HL5) derived from 5-chlorosalicylaldehyde and appropriate aminophenol and o-phenylenediamine derivatives including 4-methyl/4,5-dimethyl/4-chloro-5-nitro groups were synthesized and characterized. CoCl2, PdCl2, CuCl2 and ZnCl2 complexes of the ligands were synthesized and characterized by using elemental analysis, molar conductivity, magnetic moment, FT-IR and NMR spectroscopy. In addition, the crystal structure of H2L1 and [Pd(L-1)(CH3CN)]center dot H2O were determined by X-ray diffraction spectroscopy. Keto-enol tautomerism is observed in the Schiff base compounds according to spectral data. Antimicrobial activities of the compounds were tested toward six bacteria and three fungi. Some metal complexes (e.g. Co(II) complexes of the benzimidazole derivatives) showed higher activity towards the test microorganisms than the ligands. In addition, it is observed that the Co(II) complexes show in a wide range antimicrobial activity compared to the other complexes. (C) 2020 Elsevier B.V. All rights reserved.