Relationship between the analytical properties of lanthanide(3) β-diketonates and the nature of ligands

The effect of the nature of β-diketones on the spectrochemical and luminescence properties of lanthanide complexes used as analytical forms for the highly sensitive determination of some rare-earth elements was examined. NMR spectroscopy, molecular mechanics, calculations, and experimental evaluation of the hydrophobicity of the β-diketones indicated that an increase of the intensity, quantum yield, and lifetime of luminescence of lanthanide (Ln) β-diketonates depends on the charge distribution in the chelate ring, on the spatial structure, and on the hydrophobicity of the coordinated ligand. These factors determine the efficiency of energy transfer from the β-diketones to the Ln+3 ion and the decrease in energy losses caused by the quenching action of water molecules