Synthesis and characterization of a tetramethyl furanone functionalized diiminedioxime, a potential ligand for 64Cu radiopharmaceuticals, and its copper(II) and nickel(II) complexes

As part of our on-going effort to develop 64Cu-based radiopharmaceuticals for PET (positron emission tomography) imaging of multidrug resistance in cancer, we prepared a tetramethylfuranone-functionalized diiminedioxime ligand, TMFPreH (TMFPreH = 4-[3-(4-hydroxyimino-2,2,5,5-dimethyl-dihydro-furan-3-ylideneamino)-propylimino]-2,2,5,5-tetramethyl-dihydrofuran-3(2H)-one oxime) and its Cu(II) and Ni(II) complexes. When the copper(II) complex was prepared from Cu(ClO4)2 in ethanol, it was isolated as a Cu(II)-bridged dimer, but when it was prepared from Cu(OAc)2 and heated in acetone, an unusual example of an acetone adduct of the ligand is formed by reduction of one of the imine double bonds by the solvent. The Ni(II) complex is square pyramidal with the perchlorate counterion at the apex.

Graphical abstractA novel anionic diiminedioxime ligand containing two tetramethylfuranone moieties was prepared. A Cu(II)-bridged dimer was observed when the complex was prepared in ethanol. However, an acetone adduct of the ligand was observed when the complex was prepared in acetonitrile and acetone (figure). The Ni(II) complex is a square planar monomer.Figure optionsDownload full-size imageDownload as PowerPoint slide