Anion influence on the structure and cytotoxicity of Copper(II) complexes based on 2,2'-bipyridine/1,10-phenanthroline and benzimidazole derivative

Eight new copper(II) coordination compounds have been synthesized by the reactions of Cu(X)2 salts (X = Cl-, Br-, NO3-or ClO4-), 2,2 '-bipyridine / 1,10-phenanthroline and 1-(1H-benzimidazol-1-ylmethyl)-1H-1,2,3-ben-zotriazole (L): [Cu(bipy/phen)LCl2]& sdot;H2O (1)/(5), [Cu(bipy/phen)LBr2]& sdot;H2O (2)/(6), Cu(bipy)L2(NO3)2(H2O) (3), [Cu(bipy)L2(ClO4)2]& sdot;0.4C2H5OH (4),{[Cu(phen)L2(NO3)]NO3 & sdot;0.5H2O & sdot;0.8C2H5OH}n (7), [Cu(phen) L2(MeCN)ClO4]ClO4 (8). The complexes were characterized by CHN, thermogravimetric and high-resolution electrospray mass spectrometric analysis, IR spectroscopy, powder and single-crystal X-ray diffraction. A crystallographic study revealed that Cu:bipy/phen:L ratio, the geometry of the complexes and their nuclearity differ depending on the selected anions. Stability of the complexes in ethanol and phosphate-buffered saline was studied by UV-Vis and EPR spectroscopy. In vitro cytotoxic activity was determined against three tumor cell lines (A549, Hep2, HepG2) and non-tumor lung fibroblasts MRC5. All complexes exhibit dose-dependent cytotoxicity on tumor cells with phenanthroline-based compounds 5-8 being 3-10 times more cytotoxic than medical drug cisplatin.