Crystal structure and cytotoxic activity of Cu(ii) complexes with bis-benzoxazolylhydrazone of 2,6-diacetylpyridine

Abstract

Based on bis-hetarylhydrazone H₂L, a condensation product of 2,6-diacetylpyridine with 2-hydrazinobenzoxazole, a series of mononuclear copper(II) coordination compounds have been synthesized: [Cu(HL)NO₃], [Cu(HL)(H₂O)]ClO₄, [Cu(HL)X] (X = Br⁻, X = Cl⁻). The structure of the compounds has been studied by means of NMR, IR, ESR, X-ray absorption spectroscopy and X-ray single crystal diffraction methods. In the compounds the copper center is in the square pyramidal environment. All compounds have been screened in vitro for their cytotoxic activity against HepG2 and MRC-5 cell lines. The ligand H₂L shows no cytotoxicity at tested concentrations (1–100 μM), while all the Cu(II) complexes exhibit significant dose-dependent cytotoxic effects with IC₅₀ values in the range of 1.4–3.0 μM (HepG2 cells).