Designing Zn(II) and Cu(II) derivatives as probes for in vitro fluorescence imaging

New M( II) bis(thiosemicarbazonato) complexes ( M = Ni( II), Cu( II) and Zn( II)) featuring allyl groups at the exocyclic nitrogens have been synthesised. The complexes were characterised in solution by spectroscopic methods and their solid state structures determined by single crystal X-ray diffraction using synchrotron radiation. The Zn( II) complex was found to be intrinsically fluorescent and soluble in biocompatible media. The uptake of this Zn( II) complex in HeLa, MCF-7 and IGROV cancer cells was monitored by fluorescence microscopies ( epi- and confocal fluorescence imaging). The radiolabelling to Cu-64( II) bis( thiosemicarbazonato) complex was performed cleanly by transmetallation from the corresponding Zn( II) species using Cu-64( OAc)(2).