SYNTHESIS, X-RAY STRUCTURES, AND ANTICANCER ACTIVITY OF Co(II), Cu(II), Ni(II), AND Pd(II) COMPLEXES WITH A SALEN LIGAND DERIVED FROM TRANS -1,2-DIAMINOCYCLOHEXANE

The tetradentate salen ligand derived from (±)- trans -1,2-diaminocyclohexane and 2-hydroxy-4-dimethylaminobenzaldehyde is prepared and its complexes with Co(II), Cu(II), Ni(II), and Pd(II) are synthesized. The ligand is fully characterized by FTIR, 1 H and 13 C NMR and mass spectrometry. Structures of the metal complexes are determined by single crystal X-ray diffraction. With the exception of the Co complex that crystallizes in the monoclinic system (space group P 2 1 / c ), all the other complexes crystallize in the triclinic system with the space group P -1. All the complexes have slightly distorted square planar geometries. The ligand and the metal complexes are screened for their in vitro anticancer activity against the human breast cancer cell lines MCF-7 and T47D. In comparison with the uncomplexed ligand, the cobalt complex shows a marked antiproliferative effect.