Synthesis, structural characterization and antiproliferative potential of copper 4′-phenyl-terpyridine complexes constructed from building block reaction

Reactions between 4′-phenyl-terpyridine (L0) and Cu(II) nitrate resulted in the formation of complex [Cu(NO3)2L0](H2O) (1). Further reaction of this compound as a building block with sodium citrate, sodium benzoic and a tetra-methylpyridyl functionalized Cyclam ligand led to the compounds as [Cu(L0)2](NO3)2(H2O)1.5 (2), [Cu(ONO2)L0(OCOC6H5)](1.5H2O)(0.5CH3CN) (3) and [Cu2(NO3)2(L0)2L](NO3)2(H2O)2 (4), respectively. The four compounds were characterized by Elemental analysis, IR, UV–vis, and single crystal X-ray diffraction. Moreover, the thermal stability of 1 and 4 were determined by TG-DTA. In 1, 3 and 4, Cu ion is coordinated with one terpyridine motif and two oxygen atoms or one oxygen and one nitrogen atoms from two auxiliary ligands, resulting in a distorted CuN3O2 or CuN4O tetragonal pyramid geometry, while 2 is a sandwich structure, forming a regular-octahedron CuN6 coordination structure. The functionalized cyclam ligand L shows only one conformation with two pendant pyridyl groups coordinating to two copper ions and the other two being free in a para-mode conformation. The separation between the two copper ions in one molecule is 14.9398 (9) Å. Three human cancer cell lines were used for antiproliferative potential: human lung cancer cell line (A549), human colon cancer cell line (HCT-8) and human breast cancer cell line (MCF-7). The results have shown that these copper compounds have good inhibitory effects on cancer cells, which are better than that of the commonly used clinical drug cisplatin.