Blocking effect of ligand spacer groups on the luminescence excitation of europium aromatic carboxylates

The opportunity of luminance optimisation of europium aromatic carboxylates by modification of ligands is discussed. Luminescence, luminescence excitation spectra and luminescence efficiencies of europium phenyl-, naphthyl- and indolylcarboxylates and their adducts with 1,10-phenanthroline were investigated. Causes of variations of the luminescence efficiencies of the compounds under investigation within the range of 103 were analysed. Blocking effect of ligand spacer groups CH2 and acceptor NO2-groups on the excitation energy transfer to Eu3+ ions was examined.