New azo-azomethine based copper(II) and zinc(II) complexes: Synthesis, electrochemistry, photoluminescence properties, density functional theory calculations and molecular docking

A new bidentate azo-azomethine ligand 2-{(E)-[(3,4-dimethylphenyl) imino]methyl}-4-[(E)-(4-ethylphenyl)diazenyl]phenol (2) and its copper(II) and zinc(II) complexes (3) and (4) were synthesized and characterized by elemental analysis, 1H/13C NMR (for the ligand 2 and its Zn(II) complex) and IR spectral measurements. The structure of the ligand 2 was also determined by single crystal X-ray diffraction. The structure was solved in monoclinic unit cell and P21/n space group with final R value of 0.0586. In the structure of the ligand, the imine (CH--N) bond distance is of 1.276(2) & ANGS; which confirms the phenol-imine tautmeric form in the crystalline state. In the structure, molecules are stacked by 7C-7C (edge to edge) interactions. The electrochemical and photoluminescence properties of the synthesized azo-azomethine ligand and its metal complexes were investigated. Also, computational studies of related compounds were performed by using M062X/6-31+G level in vacuum. The potential VEGFR2 inhibitory properties of the synthesized ligand and its possible tautomers was investigated by the docking study. As for the ligand structures, azo-imine form is so reactive against the VEGFR2 protein and its docking score and total interaction energy are better than those of other tautomers.