Mercury (II) complex based on quinoxaline–aminoantipyrine: Synthesis, crystal structure, computational studies and anticancer activities evaluation

Abstract

A new complex of a heterocyclic Schiff base derived from 4-aminoantipyrine and 2-carboxaldehyde quinoxaline ((4E)-4-((quinoxalin-3-yl) methylene amino)-1, 2-dihydro-1, 5-dimethyl-2-phenylpyrazol-3-one) (L) with Hg(II) iodide, [Hg(L)I2], was synthesized and characterized using elemental analysis, FT-IR, 13CNMR and 1H NMR spectra methods. Stoichiometry of the complex was determined as 1: 1. The structure of the ligand and its mercury iodide complex was investigated using single-crystal X-ray diffraction method, which revealed that the complex had a distorted square-pyramidal geometry. In the molecular structure of the complex, the ligand coordinated to the central metal in a tridentate form (one oxygen and two nitrogen atoms as donors). The mercury atom also had a five-coordinate geometry with τ5 of 0.044. The optimization geometry, charge distribution pattern, HOMO and LUMO energy, and quantum chemical parameters for the ligand and its complex were confirmed by Density Functional Theory (DFT) calculations and NBO analysis. The synthesized compounds were tested against MCF-7 and HT-29 cancer cell lines using MTT cell viability assay. A comparative study of the IC50 values indicated that the Hg(II) complex exhibited a higher activity compared to the related free ligand against MCF-7 and HT-29 cell lines after 48 h.