Cytotoxic Copper(II) Complexes Based on 2,2'-Bipyridine/1,10-Phenanthroline and 5-(4-Chlorophenyl)-1 H -tetrazole: Synthesis and Structures

Five coordination compounds [Cu 2 (Bipy) 2 L 4 ]·C 2 H 5 OH ( Iа , Ib ), [Cu 2 (Dmbipy) 2 L 4 ] ( II ), [Cu 2 (Phen) 2 L 4 ]·H 2 O ( IIIa ), [Cu 2 (Dmphen) 2 L 4 ] ( IVa ), and [Cu 2 (Phendione’) 2 L 4 ]·2C 2 H 5 OH·2H 2 O ( V ) are synthesized from 5-(4-chlorophenyl)-1 H -tetrazole (HL), where Bipy is 2,2'-bipyridine, Dmbipy is 4,4'-dimethyl-2,2'-bipyridine, Phen is 1,10-phenanthroline, Dmphen is 4,7-dimethyl-1,10-phenanthroline, and Phendione’ is 6-ethoxy-6-hydroxy-1,10-phenanthrolin-5-one. The crystal structures of the complexes are determined by X-ray diffraction (XRD) of single crystals (CIF files CCDC nos. 2225368 ( Ia ), 2225369 ( Ib ), 2225370 ( II ), 2225372 ( IIIa ), 2225373 ( IVa ), and 2225371 ( V )). The compounds are binuclear due to the bridging function of the tetrazolate anion, and the coordination number of copper is five in all synthesized complexes. The cytotoxic activity of the complexes against the Hep2 and HepG2 cancer cell lines and non-cancerous human fibroblasts MRC-5 is studied. The complexes exhibit pronounced cytotoxic properties, and compound V has the maximum selectivity index with respect to the cancer cells.