No abstract

A new bidentate Schiff base ligand (ATBS [4‐bromo‐2‐(thiazole‐2‐yliminomethyl)phenol]) was synthesized via the condensation reaction of 2‐aminothiazole with 5‐bromosalicylaldehyde in ethanol. The reaction of ATBS with transition metal salts of Cu(II), Co(II), Ni(II), and Mn(II) afforded the corresponding ATBS–M complexes. Results from physicochemical and spectral analyses, such as elemental analysis, infrared, UV–Vis spectroscopy, magnetic susceptibility, and molar conductance, revealed a nonelectrolytic nature with octahedral (Oh) geometry and a metal/ligand ratio of 1:2 for Cu(II), Co(II), and Ni(II), but 1:1 for the Mn(II) complex. The density functional theory (DFT) calculations are correlated very well with the proposed structure and molecular geometry of the complexes as [M(ATBS)2] (M = Cu, Co, and Ni) and [Mn(ATBS)(H2O)2]. Significantly, the prepared compounds showed strong inhibition activity for a wide spectrum of bacteria (Escherichia coli, Bacillus subtilis, and Staphylococcus aureus) and fungi (Candida albicans, Aspergillus flavus, and Trichophyton rubrum), with the ATBS–Ni complex being the most promising antibiotic agent. Molecular docking studies of the binding interaction between the title complexes with the bacterial protein receptor CYP51 revealed clear insights about the inhibition nature against the studied microorganisms, with the following order: ATBS–Cu > ATBS–Mn > ATBS–Ni > ATBS–Co for complex stability. Moreover, the cytotoxicity measurements of all prepared metal complexes against the colon carcinoma (HCT‐116) and hepatocellular carcinoma (Hep‐G2) cell lines showed exceptional anticancer efficacy of the complexes as compared with the free ATBS Schiff base ligand. Significantly, the results attested that ATBS–Cu is the most effective complex against HCT‐116 cells, whereas ATBS–Mn has the highest cytotoxic efficiency against Hep‐G2 cells. Furthermore, electronic spectra, viscosity measurements, and gel electrophoresis techniques were employed to probe the interaction of all prepared ATBS–metal complexes with calf thymus (CT)‐DNA. Results confirmed that all complexes are strongly bound to CT‐DNA via intercalation mode, with the ATBS–Co complex having the highest binding ability.

The conversion of nitro compounds to their corresponding amino compounds by reduction route is a significant chemical reaction from an industrial and environmental standpoint. In the present paper, copper Schiff base complex was successfully prepared from the reaction between (1, 1 -(pyridine-2,3-dimethyl imino methyl)naphthalene-2,2 -diol) and Cu(CH3COO)2 salt. This was successfully characterized with different techniques and grafted over graphene oxide (GO) as support after functionalizing it via chemical grafting using aminopropyltriethoxysilane (APTES) as a linker to obtain the functionalized form (FGO). The new heterogeneous complex (CuMGO) was depicted using physicochemical and spectroscopic tools such as FT-IR, UV-Vis, SEM, XRD, Raman spectroscopy, and XPS. The results manifest that Cu(II) imine complex was successfully immobilized on GO. The resulting catalyst was used to reduce 4-nitrophenol (4-NP) to its corresponding amine 4-aminophenol (4-AP) at room temperature in case of using hydrazine hydrate as a reducing agent. It showed good activity with a percent of conversion (44.4%) and an apparent rate constant of 2.06 × 10-3 min-1 in about 130 min. The prepared catalyst can be recycled five times without losing its activity.