Low-dimensional compounds containing bioactive ligands. Part XIII: Square planar anti-cancer Pd(II) complexes with halogenderivatives of 8-quinolinol and dimethylamine

Four new Pd(II) complexes with halogenderivatives of 8-quinolinol (HXQ) were prepared: [PdCl(NH(CH3)(2))(CQ)] (1), [PdCl(NH(CH3)(2))(dClQ)] (2), [PdCl(NH(CH3)(2))(dBrQ)] (3) and [PdCl(NH(CH3)(2))(BrQ)] (4), where HCQ is 5-chloro-7-iodo-8-quinolinol, HdClQ is 5,7-dichloro-8-quinolinol, HdBrQ is 5,7-dibromo-8-quinolinol and HBrQ is 7-bromo-8-quinolinol. The infrared spectroscopy confirmed the presence of XQ moiety in all complexes as well as dimethylamine ligands resulting from the decomposition of DMF used as solvent. Subsequent X-ray structural analysis confirmed that XQ ligands are chelate bind to Pd(II) atom through oxygen and nitrogen atoms, the dimethylamine molecules are attached via nitrogen atom, wherein the nitrogen atoms of XQ and of dimethylamine are in trans-positions. The fourth coordination place is occupied by chloride ligand, suggesting a square planar configuration of the central Pd(II) atom. The structures are stabilized by both H-bonds and pi-pi interactions while observing the formation of 2D or 3D structures. H-1 and C-13 NMR spectra of 1-4 confirmed their stability in dimethylsulfoxide. The radical scavenging experiments revealed relatively low antioxidant properties with 1 being the most potent antioxidant among prepared complexes. In vitro antiproliferative properties of the newly prepared complexes were studied on adenocarcinomic human alveolar basal epithelial cells A549, human colon cancer cell line HCT116, human breast cancer cell line MDA-MB-231 and their selectivity was studied on non-cancerous mouse mesenchymal stem cells MSCs. All the prepared complexes were toxic to the tumor cells and the higher cytotoxicity was induced by complex 1 against A549 cells at very low concentrations which would provide new potential antitumor drug that deserves much more attention in lung cancer research. (C) 2020 Elsevier Ltd. All rights reserved.