Mononuclear ZnII complex of a hexadentateiminophenolate-based O,O,N,N,O,O ligand: Experimental and theoretical vision

Abstract

ABSTRACT: Mononuclear complex of composition [ZnII(L)].2H2O (1) (H2L = 2-((Z)-(2-(2-(2-((Z)-3,5-di-tert-butyl-2-hydroxybenzylideneamino)phenoxy)ethoxy)phenylimino)methyl)-4,6-di-tert‑butylphenol) has been synthesized and characterized. In the complex 1, the ZnII at the center is coordinated by two imine nitrogen atoms, two phenolate oxygen atoms and one ether oxygen atom from the ligand, resulting in a distorted square-pyramidal ZnN2O3 coordination geometry. Complex 1 is photoluminescence active with stokes shift of 115 nm. Geometrical parameters were computed using the Density Functional Theory (DFT) method, specifically B3LYP, with the 6–311G++(d,p) basis sets. The charge distribution within the molecule was visualized through Molecular Electrostatic Potential (MEP) surface analysis. The energy levels of the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) were determined that revealing substantial charge transfer within the molecule. Hirshfeld surface analysis was conducted in both three-dimensional (3D) and two-dimensional (2D) perspectives to investigate the electron distribution on the molecular surface. The Electron Localization Function (ELF) Figure was utilized to investigate the degree of relative electron localization within the molecule. Moreover, a Fukui functional analysis was employed to identify potential sites for chemical attack by different substituents. The process involved in the creation of the molecular electrostatic potential (MEP), followed by the generation of a three-dimensional color-coded visualization to emphasize reactive areas. In the realm of biological investigation, four separate receptors such as 5HL1, 8BSK, 6UJM and 6UL9 were utilized for molecular docking analyses. These analyses aimed to evaluate interactions between ligands and proteins, as well as to uncover potential resemblances among drugs.

Keywords

• Schiff-base ligand
• Zinc-complex
• X-ray structure
• Photoluminescence
• ELF
• MEP