Dihaloplatinum(II) complexes having diimine ligands: crystal structure, thermal properties, cytotoxicity effects against breast cancer cells and application as a precursor towards nanoparticles

Abstract

The reaction of potassium tetrachloroplatinate(II) with dimethylsulfide and a mixture of HBr/KBr affords trans-[PtBr2(SMe2)2]; [PtBr2(Me2bpy)] (Me2bpy = 4,4'-dimethyl-2,2'-bipyridine) was prepared from the reaction of trans-[PtBr2(SMe2)2] with Me2bpy. The crystal structure of the yellow form of [PtBr2(bu2bpy)] (bu2bpy = 4,4'-di-tert-butyl-2,2'-bipyridine) was determined by X-ray crystallography. The X-ray single-crystal structure determination of complex [PtBr2(bu2bpy)] reveals that the platinum adopts a square planar geometry with a twofold axis through the platinum atoms. Thermal properties of the related series of diimine platinum(II) complexes [PtX2(bu2bpy)] (X = Cl, Br, I) reveal that the thermal stabilities increase [PtI2(bu2bpy)] < [PtCl2(bu2bpy)] < [PtBr2(bu2bpy)]. [PtBr2(bpy)] (bpy = 2,2'-bipyridine), [PtBr2(Me2bpy)] and [PtX2(bu2bpy)] (X = Cl, Br, I) were studied by MTT assay against two human breast cancer cell lines of MCF-7 and MDA-MB-468 with [PtCl2(bu2bpy)] having a higher cytotoxic effect towards both cancer cell lines, which shows the significant role of the halide and diimine ligand. Semi-spherical Pt(0) nanoparticles (NPCs) were prepared by the simple calcination of [PtX2(bu2bpy)] (X = Cl, Br, I) at 800 °C in air.