Reassessing the compound CeCd6: the structure of Ce6Cd37

The complexes RE(DTPA–pAS), RE(DTPA–2pAS), and RE(DTPA)(pAS)2 (RE=Tb or Eu) are synthesized and characterized by elemental analysis, IR spectra and UV spectra. Their luminescent properties are investigated by determining fluorescence intensities, fluorescence lifetimes and fluorescence quantum yields. All ligands enhance the TbIII luminescence more efficiently than the EuIII luminescence. The fluorescence of the complex Tb(DTPA)(pAS)2 is more intense than Tb(DTPA–pAS) and Tb (DTPA–2pAS), and it is stable even in highly dilute solution. It is possible that the complex could be used as a label in fluoroimmunoassays.