Synthesis, Crystal Structure and Anticancer Studies of Cubane-Type Ni(II) Complex Derived from 5-bromosalicylaldehyde-2-aminophenol Schiff Base

The Schiff base ligand (5-bromosalicylaldehyde)-2-aminophenol (H 2 L) and its complex were synthesized and characterized. The crystal structure was established by single-crystal X-ray diffraction, which showed that the monomer [Ni 4 L 4 (CH 3 CH 2 OH) 4 ]·1.46(CH 3 CH 2 OH) (the Ni(II) complex) crystallized in the tetragonal structure with space group I 4 1 / a . IR, elemental analysis, and thermogravimetric analysis were used to further confirm the structure of the Ni(II) complex. Its independent unit consists of four Ni(II) atoms, four L 2− Schiff base ligands, and four coordinated ethanol molecules. In vitro anticancer activities against the four human cell lines, A-549, MDA-MB-231, SMMC-7721, and CNE-2Z, revealed that the Ni(II) complex exhibited significant anticancer activity. Furthermore, the anticancer activities of the Ni(II) complex on SMMC-7721 and CNE-2Z cells were much better than that of cisplatin. In addition, migration and the Transwell assay illustrated that the Ni(II) complex could inhibit the invasion and cell migration of tumor cells CNE-2Z and SMMC-7721.