Low-dimensional compounds containing bioactive ligands. Part XXIII: A comprehensive study of the preparation and cytotoxic activities of zirconium(IV) complexes with 8-hydroxyquinoline and its derivatives

Nine zirconium(IV) complexes, [Zr(8-HQ)4]& sdot;DMF & sdot;H2O (1), [Zr(dClQ)4]& sdot;EtOH (2), [Zr(ClNQ)4]& sdot;EtOH (3a), [Zr (ClNQ)4]& sdot;DMF (3b), [Zr(BrQ)4] (4), [Zr(dBrQ)4]& sdot;DME (5), [Zr(2-MedBrQ)4]& sdot;2DMF (6), [Zr2Cl2(CQ)4 mu 2-O (DMF)2]& sdot;0.33DMF (7), and [Zr2Cl2(ClBrQ)4 mu 2-O(DMF)2]& sdot;DMF (8) (DME = 1,2-dimethoxyethane, H8-HQ = 8hydroxyquinoline, HdClQ = 5,7-dichloro-8-hydroxyquinoline, HClNQ = 5-chloro-7-nitro-8-hydroxyquinoline, HBrQ = 7-bromo-8-hydroxyquinoline, HdBrQ = 5,7-dibromo-8-hydroxyquinoline, H2-MedBrQ = 2-methyl-5,7dibromo-8-hydroxyquinoline, HCQ = 5-chloro-7-iodo-8-hydroxyquinoline, HClBrQ = 5-chloro-7-bromo-8hydroxyquinoline), have been prepared and characterized by elemental, single crystal X-ray structure analysis and IR spectroscopy. Complexes 1 - 6 are mononuclear complexes with Zr(IV) atoms octacoordinated by four bidentate quinoline ligands. Complexes 7 and 8 are binuclear complexes in which two Zr(IV) atoms are coordinated by two bidentate quinoline, one DMF and one chloro ligands, and the seventh coordination place occupies an oxygen atom bridging both complex species. The stability of complexes soluble in a DMSO was verified by NMR spectroscopy. In vitro cytotoxic properties of complexes 1, 2, 4, 5, and 6, and corresponding ligands were studied against 8 cancer cell lines, and their selectivity was verified on BJ-5ta non-cancerous cell line. The most potent complexes are 1 and 4 with the smallest quinoline ligands.