Synthesis, theoretical investigations, biocidal screening, DNA binding, in vitro cytotoxicity and molecular docking of novel Cu (II), Pd (II) and Ag (I) complexes of chlorobenzylidene Schiff base: Promising antibiotic and anticancer agents

Three new Cu (II), Pd (II) and Ag (I) complexes of bidentate Schiff base ligand 2-[(4-chlorobenzylidene)amino] phenol (HL) were synthesized. The stoichiometric ratios and physicochemical properties of these complexes were determined using elemental analyses, magnetic measurements, infrared and UV-visible spectra, molar conductivity measurements and thermal analyses. The results revealed that the metal ions coordinated with through azomethine nitrogen and phenolic oxygen atoms. AgL and PdL complexes are present in a 1:1 molar ratio with square planar and tetrahedral geometry, respectively, while CuL2 complex is present in a 1:2 molar ratio with octahedral geometry. The electronic structure and nonlinear optical parameters of HL and the studied 1:1 and 1:2 complexes were investigated theoretically at the DFT-B3LYP/6-311G** level of theory. The compounds were screened against various strains of bacteria and fungi. They displayed good results for inhibition against the studied pathogenic microorganisms. Absorption spectroscopic, viscosity and gel electrophoresis measurements were used for studying the interaction of the prepared complexes with calf thymus DNA (CT-DNA). The studied complexes showed a good interaction with CT-DNA via intercalation and groove modes. Moreover, molecular docking of these complexes was studied to understand the drug-DNA interactions and calculate the potential binding mode and energy. The anticancer effects of HL and its complexes, on selected human carcinoma cell lines, were determined. The cytotoxicity results showed that the prepared complexes are more potent than the Schiff base ligand.