Synthesis, crystal structures and biological evaluation of three ternary copper(II) complexes with fluorinated anthranilic acid derivatives

Three ternary copper(II) complexes [Cu(L 1 )(phen)] ( 1 ), [Cu(L 2 )(phen)] ( 2 ), and [Cu(L 3 )(phen)] · 2H 2 O ( 3 ) (L 1  = 4-fluoro-2-(picolinamido)benzoic acid, L 2  = 4,5-difluoro-2-(picolinamido)benzoic acid, L 3  = 4,5-difluoro-2-((2-hydroxybenzylidene)amino)benzoic acid, phen = 1,10-phenanthroline) have been synthesized and characterized by physicochemical and spectroscopic methods. In addition, X-ray crystallography showed that the Cu atoms in each of the complexes are five-coordinate, adopting distorted square pyramidal or trigonal bipyramidal geometries. The interactions of the complexes with calf-thymus DNA were investigated by UV absorption, fluorescence spectroscopy and viscosity measurements. In addition, the complexes were screened for in vitro cytotoxicity against A549 (human pulmonary carcinoma cells), Jurkat (human T lymphocyte cell line) and HepG-2 (human liver hepatocellular carcinoma cells); these experiments showed that complex 3 exhibited the most effective cytotoxicities (IC 50  = 1.224–7.099 µM). Antibacterial studies revealed that complex 3 also exhibited highest activity, consistent with the DNA binding affinities.