Synthesis of Nano-Metric Gold Complexes with New Schiff Bases Derived from 4-Aminoantipyrene, Their Structures and Anticancer Activity

Abstract

Two new Schiff bases derived from combination of 4-aminoantipyrine with ethylenediamine (L₁) or benzaldehyde (L₂), gave Au(III) complexes. Their structures were elucidated from microanalytical, magnetic, conductance, and FT-IR, UV-Vis, Mass, and ¹H and ¹³C NMR spectral data. High conductance values indicated electrolytic nature of the complexes. Magnetic moments and electronic spectral data indicated that two synthesized Au(III) Schiff base complexes had a square planar geometry. FT-IR spectroscopic data demonstrated that the Schiff bases were coordinated to Au(III) ions in a tetradentate manner with NNNN donor sites of two 4-amino antipyrine and two azomethine (L₁), while L₂ Schiff base ligand coordinated to Au(III) ions via its four azomethine nitrogen, which was further supported by the appearance of new bands in IR spectra due to ν(M–N). Activation thermodynamic parameters (E*, ΔH*, ΔS*, and ΔG*) were calculated on the basis of TG curves. Crystalline structures of Schiff bases and their Au(III) complexes were characterized by X-ray diffraction (XRD), their morphology was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Schiff base ligands and their Au(III) chelates were screened for their antimicrobial activity. Cytotoxic activity of those was tested against the human breast cancer (MCF-7) and human hepatocellular carcinoma (HepG-2) tumor cell lines.