A zinc(II) quinolinone complex (Et3NH)[Zn(qui)Cl2]: Synthesis, X-ray structure, spectral properties and in vitro cytotoxicity

Article abstract of DOI:10.1016/j.molstruc.2013.12.050

A new zinc(II) complex with 2-phenyl-3-hydroxy-4(1H)-quinolinone (Hqui) of the composition (Et₃NH)[Zn(qui)Cl₂] was prepared and characterized by elemental analysis, FT IR, 1D and 2D NMR, and fluorescence spectroscopy, mass spectrometry and single crystal X-ray analysis. The molecular structure is composed of the triethylammonium (Et₃NH⁺) cations and tetrahedral [Zn^II(qui)Cl₂]^- complex anions, in which the Zn(II) atoms are bidentate coordinated by one qui ligand through keto (O_K) and phenolate (O_P) oxygen atoms and by two chlorido ligands, thus forming the {O₂Cl₂} donor set, with Zn-O_K = 1.9860(14) ?, Zn-O_P 1.9961(14) ? and Zn-Cl = 2.2509(6) ? and 2.2266(6) ?. The complex cations are aligned into 1D supramolecular chains through the NHa?Cl hydrogen bonding between the amine group of the quinolinone ligand and the chlorido ligand of the adjacent complex anion. The amine group from the Et ₃NH⁺ cations provides the NHa?O_P hydrogen bond with the phenolate oxygen atoms from the complex anion. Screening of in vitro cytotoxicity of the compound was studied on human osteosarcoma (HOS) and human breast adenocarcinoma (MCF7) cell lines, with IC₅₀ > 50 μM. The fluorescence study showed that the complex exhibits a relatively high integral intensity (29%) as compared to the standard quinine sulfate, and 1.6-fold enhancement of emission with respect to free Hqui.