Synthesis, characterization, and crystal features of a mixed ligand binuclear Zinc(II) acyl pyrazolone complex: DFT, Hirshfeld surface analysis and anti-malarial activity evaluation

A novel binuclear [Zn₂(L₂C)₂(HQ)₂] complex with mixed ligands was synthesized using pyrazolone-based derivative (L₂C) (1-(3-chlorophenyl)-5-hydroxy-3-methyl-1H-pyrazol-4-yl)(4-nitrophenyl)methanone) as the primary ligand and 8-hydroxyquinoline (8-HQ) as the secondary ligand. Single crystal analysis revealed that each zinc(II) atom is penta-coordinated, involving four O-atoms from two pyrazolone ligands and two N-atoms from the 8-hydroxyquinoline. Two hydroxyl O-atoms from the 8-hydroxyquinoline also bridge the zinc atoms, leading to a distorted square pyramidal geometry. The structure of the complex was further characterized using ¹H NMR, FT-IR, UV–vis, TGA, and elemental analysis. The compounds’ electronic behaviour, stable geometry, MEP surfaces, and FMO analysis were studied using density functional theory (DFT) at the B3LYP level with the LanL2DZ basis set. These theoretical results were compared with the experimental structural data of the [Zn₂(L₂C)₂(HQ)₂] complex. The complex was tested for its ability to inhibit Plasmodium falciparum in vitro.