Chemical synthesis, in vitro biological evaluation and theoretical investigations of transition metal complexes derived from 2-(((5-mercapto-1H-pyrrol-2-yl)imino) methyl)6-methoxyphenol

In the present work we have synthesized a Schiffbase ligand, (HL) derived from 5-amino-4H-1,2,4-triazole-3-thiol and 4-hydroxy-3-methoxybenzaldehyde and its Co(II), Cu(II), Ni(II) and Zn(II) which are assigned as 1, 2, 3 and 4, respectively, in 2:1 stoichiometric ratio (2HL:M). The structures of the ligand and its metal complexes were evaluated using Fourier Transform Infrared Spectroscopy (FT-IR), Ultraviolet-visible spectroscopy (UV-Vis), Mass spectroscopy (MS), Nuclear magnetic resonance (H-1 and C-13-NMR) and Thermogravimetric (TGA) methods. The Schiffbase ligand and its metal complexes were tested for in vitro antibacterial activities by using disc diffusion method and minimum inhibitory concentration (MIC) method by using Amoxicillin (1 mg/ml) and Dimethylsulfoxide (DMSO) as positive and negative control, respectively. The free radical scavenging ability of compounds was assessed by employing a series of in vitro assays viz., 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and Superoxide whereas Butylated hydroxyanisole (BHA) was used as a positive control. In vitro alpha-glucosidase inhibitory studies revealed that metal complexes had significant inhibitory potential than the ligand. The molecular docking studies were carried out on the prepared ligand and receptor molecules using AutoDock 4.2. The research was complemented by performing computational Density Functional Theory (DFT) studies on the chemical reactivity of the ligand and the three complexes by means of Conceptual Density Functional Theory (CDFT) through the Koopmans in DFT(KID) approximation. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, a new Schiff base ligand and its metal complexes were synthesized and characterized using various spectroscopic methods. Their antibacterial activities were evaluated, showing potential for future applications in medicine.