Synthesis, structure and anticancer studies of Cu (II), Ni (II) and Co (II) complexes based on 2,3-dihydroxybenzaldehyde-2-(2-aminophenyl)benzimidazole Schiff base

Three metal complexes [Cu(HL)Cl](C2H5OH)2] (complex 1), [Ni4L2(CH3COO)4(C2H5OH)4] (complex 2) and [CoHL2] (complex 3) based on 2,3-dihydroxybenzaldehyde-2-(2-aminophenyl)benzimidazole Schiff base (H2L) were synthesized by solvothermal reaction. The three complexes were characterized by FT-IR spectrometer, elemental analysis, thermogravimetric analysis, and X-ray single-crystal diffraction. X-ray single-crystal diffraction analysis confirmed that complex 1 belongs to monoclinic crystal system with P21/c space group, and complex 3 crystallizes in trigonal crystal system with R-3 space group. However, complex 2 crystallized in triclinic crystal system with P-1 space group and exhibits centrosymmetric tetranuclear crystallographic structure. Besides, MTT assay was studied antitumor activities against different tumor cells. The results show that the three complexes all have fine anticancer activities. Among them, complex 2 has significantly better anticancer properties against CNE-2Z cells than that of cisplatin. Finally, apoptosis and cell migration were studied to prove that complex 2 could inhibit tumor cells from proliferating in the manner of apoptosis and migration.