Copper(II) complexes with β-diketones and N-donor heterocyclic ligands: Crystal structure, spectral properties, and cytotoxic activity

Abstract

This work reports on the synthesis and characterization of new complexes of the type [Cu(O–O)(N–N)X], where O–O=4,4,4-trifluoro-1-phenyl-1,3-butanedione (HBTA), 1-(4-chlorophenyl)-4,4,4-trifluoro-1,3-butanedione (HBTACl) or 2-thenoyltrifluoroacetone (HTTA); N–N=2,2-bipyridine (Bipy) or 1,10-phenanthroline (Phen) and X=NO3− or ClO4−. These complexes were characterized by elemental analyses, conductivity measurements, FT-IR, UV–Vis, EPR, High-resolution Electrospray Ionization Mass Spectrometry (HRESIMS) and TG/DTA. The X-ray structural analysis of two representative compounds indicates that the geometry around the copper ion is distorted square-pyramidal and it is coordinated to β-diketone via the oxygen atoms and to N-donor heterocyclic ligands via its two nitrogen atoms. A perchlorate or nitrate ion weakly bonded occupies the apical position, completing the coordination sphere. The crystal packing is stabilized by non-classical hydrogen bonds and weak interactions π–π stacking. The cytotoxic activity of compounds was investigated in a chronic myelogenous leukemia cell line. The complexes with 1,10-phenanthroline are more active than carboplatin. As example, the compound [Cu(BTACl)(Phen)NO3] inhibits the growth of K562 cells with an IC50 value equal to 2.1μM.