Synthesis, structure, and anticancer studies of Cu (II) and Ni (II) complexes based on (5‐chlorosalicylaldehyde)‐4‐aminoantipyrine Schiff base

Two dinuclear complexes [Cu 2 (LO) 2 ] and [Ni 2 L 2 Cl 2 (C 2 H 5 OH) 2 ] derived from (5‐chlorosalicylaldehyde)‐4‐aminoantipyrine (HL) were synthesized and characterized by infrared (IR) spectroscopy，thermogravimetric analysis, and powder X‐ray diffraction. Molecular structures of the Cu (II) and Ni (II) complexes were determined by single‐crystal X‐ray diffraction. Their cytotoxicity was evaluated by methyl thiazolyl tetrazolium assay against human tumor cells, such as lung carcinoma A549, lung adenocarcinoma H1975, breast carcinoma MDA‐MB‐231, and nasopharyngeal carcinoma CNE‐2Z cell lines. The results showed that the Cu (II) complex had much better anticancer activity than the Ni (II) complex, especially for MDA‐MB‐231 and CNE‐2Z cells. The reason may be that they have different structures. The methyl group on the (5‐chlorosalicylaldehyde)‐4‐aminoantipyrine (HL) was oxidized to the hydroxymethyl group, herein, namely LO, which is difficult to achieve in the normal chemical synthesis process. However, we did it by a solvothermal method at low temperature. It provides a new way of thinking and synthesis. The anticancer activity of the copper complex was next only to cisplatin, and the copper complex was nontoxic for the human normal cell lines. The experiment results also showed that the copper complex could inhibit tumor cell proliferation through the cell cycle and cell apoptosis.