Synthesis, characterization, and anticancer properties of organometallic Schiff base platinum complexes

Abstract

A small family of organometallic platinum complexes containing a chloride, cis-cyclooctene, and a Schiff base ligand have been prepared and characterized fully. Three aliphatic amines and four aromatic amines were chosen as representative examples. All complexes were stable in air except for 7, derived from the pinacol-protected 4-aminophenylboronate ester 4-H2NC6H4Bpin (pin = 1,2-O2C2Me4), which decomposed via B–C bond cleavage. Both complexes 4 (derived from aniline) and 7 were further characterized by single-crystal X-ray diffraction studies and confirmed the square planar nature of the platinum centre whereby the chloride ligand lies trans to the deprotonated hydroxyl group of the Schiff base ligand. The imine functionality is trans to the organic cyclooctene group. Complex 3, which contained the longest aliphatic chain studied (an octyl group), was the most promising for inducing apoptosis in the malignant MB231 breast cancer cell line. Conversely, complexes 4–6, which contained aromatic groups, were the most active against renal cell carcinoma (RCC) cell lines.