The reactions between equimolar amounts of CuX 2 (X = NO 3 À and CF 3 SO 3 À ) and two aromatic nitrogencontaining heterocycles differing in the position of nitrogen atoms, 1,7-and 4,7-phenanthroline (1,7and 4,7-phen), were performed in ethanol/methanol at room temperature. When CuX 2 salts were mixed with 4,7-phen, two copper(II) complexes, [Cu(NO 3 ) 2 (4,7-Hphen) 2 ](NO 3 ) 2 (1) and [Cu(CF 3 SO 3 )(4,7phen) 2 (H 2 O) 2 ]CF 3 SO 3 (2), were formed. On the other hand, in the reaction of CuX 2 salts with 1,7-phen, only 1,7-HphenNO 3 (3a/b) and 1,7-HphenCF 3 SO 3 (4) were obtained as the final products. The obtained products 1-4 were characterized by spectroscopic and X-ray diffraction techniques. In the copper(II) complexes 1 and 2, the coordination geometry around the Cu(II) ion is distorted octahedral and square pyramidal, respectively. The antimicrobial potential of the copper(II) complexes 1 and 2 and corresponding compounds used for their synthesis were assessed against four different bacterial species and Candida albicans, displaying moderate growth inhibiting activity. The cytotoxic properties of the investigated complexes were also evaluated against the normal human lung fibroblast cell line (MRC-5) indicating moderate, yet more pronounced cytotoxicity than antimicrobial properties. ⇑ Corresponding author. Fax: +381 34 335 040.