New homoleptic imine derivative of lawsone and its metal complexes: Preparation, characterization, in vitro and in silico biological investigation

Abstract

In this article, a Schiff base derivative has been prepared using 2‐hydroxy‐1,4‐naphthoquinone and 3‐amino‐1,2,4‐triazole, and consecutively, four metal complexes (Co(II), Ni(II), Cu(II) and Zn(II)) have been synthesized using this Schiff base derivative as precursor ligand. Characterization of the synthesized compounds are done by employing spectral techniques such as UV–vis, infrared (IR), nuclear magnetic resonance (NMR), mass and electron paramagnetic resonance (EPR). All these methods establish the existence of imine group and the octahedral geometry of the complexes. The synthesized complexes are evaluated for their DNA binding properties that confirm that the binding mode is intercalation. The bioactive ligand and its complexes also exhibit pronounced pharmacological activities such as antioxidant and antimicrobial activities against bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Salmonella typhi; fungi, namely, Aspergillus niger, Aspergillus flavus, Candida albicans and Rhizoctonia bataticola. Moreover, the compounds are examined for their density functional theory (DFT) studies using Gaussian 09 programme. Various reactivity descriptors are calculated based on the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO‐LUMO) energies. Molecular docking is conducted with two different receptors 1BNA and 1HD2 proteins to get a wide knowledge on the in vitro biological examination and also the interaction of the compounds with different proteins.