Isophthaloylbis (Azanediyl) Dipeptide Ligand and Its Complexes: Structural Study, Spectroscopic, Molecular Orbital, Molecular Docking, and Biological Activity Properties

Abstract

The ligand 2,2′-(isophthaloylbis(azanediyl))bis(3-phenylpropanoic acid; H2L) was used to build novel metal complexes of Co(II), Ni(II), Fe(III), and Zn(II) metal ions. Elemental analyses, thermal, infrared, mass, electronic spectra, magnetic moments, X-ray diffraction analysis, and conductivity measurements were used to predict the nature of bonding and the stereochemistry of the complexes. The complexes were proposed to have the general formula [M(H2L)(H2O)2]Cl n , where M = Co(II), Ni(II), and Zn(II) (n = 2) and Fe(III) (n = 3), based on the elemental analyses data. All of the complexes were electrolytes, according to the molar conductivity measurements. The FT-IR spectra revealed that the dipeptide ligand is tetradentately coordinated to metal ions, with NNOO donor atoms participating in coordination with metal (II)/(III) ions, resulting in octahedral complexes. Using the recommended programme, the structural formula for the investigated ligand was optimized. Using the density-functional theory (DFT) approach, the energy gaps and other essential theoretical parameters were calculated. The agar diffusion method was used to test the in vitro biological characteristics of the ligand (H2L) and its transition metal complexes against Gram(+) bacteria (Bacillis subtilis and Staphylococcus aureus) and Gram(−) bacteria (Escherichia coli and Pseudomonas aeruginosa). The title compounds were found to be more biologically active than the parent dipeptide ligand. The title compounds have a good interaction with the crystal structures of 3t88-Escherichia coli, 3ty7-S. aureus, 5h67-Bacillus subtilis, and 5i39-Pseudomonasaeruginosa, according to molecular docking study.