Inner metal complexes of tetradentate Schiff base: Synthesis, characterization, biological activity and molecular docking studies

Abstract

A novel Schiff base ligand, namely 2,2′‐((1E,1′E)‐(1,3‐phenylenebis(azanylylidene))bis(methanylylidene))diphenol (H2L), was synthesized by condensation of m‐phenylenediamine and 2‐hydroxybenzaldehyde (in 1:2 ratio). Series of complexes were obtained from the reaction of La(III), Er(III) and Yb(III) chlorides with H2L. The ligand and complexes were characterized using elemental analysis, infrared, 1H NMR, UV–visible and mass spectroscopies, magnetic susceptibility and conductivity measurements and thermal analysis. Infrared and 1H NMR spectra indicated the coordination of the azomethine nitrogens and deprotonated phenolic oxygen atoms in a tetradentate manner (ONNO). The thermal behaviour of the complexes was studied from ambient temperature to 1000°C. The complexes were found to have water molecules of hydration and coordinated water molecules. The complexes were found to possess high biological activities against various organisms compared to the free ligand (Gram‐positive bacteria Staphylococcus aureus and Bacillus subtilis, Gram‐negative bacteria Salmonella sp., Escherichia coli and Pseudomonas aeruginosa and fungi Aspergillus fumigatus and Candida albicans). The more effective and probable binding modes between H2L with different active sites of colon cancer (PDB code: 2hq6) and lung cancer (PDB code: 1x2j) receptors were investigated using molecular docking studies.

Antibacterial and anticorrosion behavior of bioactive complexes of selected transition metal ions with new 2‐acetylpyridine Schiff base

“…Also, new two bands at 865–871 and 778–787 cm −1 advised the presence of coordinated water in all‐metal complexes. [ 51,52 ] Furthermore, the band seemed at 691 cm −1 that corresponds to the ν (NH 2 ) bending in the Schiff base was still in the complexes at the same position (689–693 cm −1 ). [ 31 ] This indicated the non‐participation of nitrogen of amino group in binding to metal ions.…”

“…[ 54 ] Furthermore, singlet signal was observed at 4.75 and 4.86 ppm which referred to NH 2 group in ligand and Cd(II) complex, respectively. [ 52 ] The aromatic protons of benzene and pyridine rings (12H) of the ligand were shown as multiplet signals at 6.49–6.65 ppm. These peaks still appeared in Cd(II) complex in the same range at 6.50–6.64 ppm.…”

Heliotropium ramosissimum metabolic profiling, in silico and in vitro evaluation with potent selective cytotoxicity against colorectal carcinoma

“…We performed docking studies using Molecular Operating Environment (MOE, 2014.0901) 27 . We retrieved the three-dimensional (3D) structures of serologically defined colon cancer antigen 10 (PDB ID: 2HQ6) determined by X-ray diffraction (resolution: 1.75 Å) from the RCSB Protein Data Bank ( https://www.rcsb.org/ ) and used it as a target in our molecular docking experiments 28 . We prepared and optimized the structure of the receptor protein using MOE’s ligx function with default settings.…”

Structural Characterization, DFT Geometry Optimization, Cyclic Voltammetry and Biological Assay of (Tellurite-pyridine) Mixed Ligandcomplexesof Cd(II)

“…Molecular docking calculations were carried out using docking server [31]. Gasteiger partial charges were added to the atoms of ligand.…”