[Synthesis, characterization and photoluminescence properties of (EuxRE1-x)(beta-NTA)3phen complexes]

Two series of solid complexes of EuxRE1-x(beta-NTA)3 phen (RE = Y3+ and Tb3+, x = 0.10, 0.30, 0.50, 0.70, 0.90) were synthesized in alcohol. They were characterized by elemental analysis, IR spectra, molar conductivity, 1H NMR spectra and TG-DTA. The molar conductivity indicated that all the complexes were nonelectrolyte; and 1H NMR spectra and IR spectra showed that the ligand coordinates(double-tooth) with RE3+ ions through the oxygen negative ion of enolic form of beta-NTA and the two nitrogen atoms of phen. The fluorescence properties of these complexes were studied, the results indicated that the chemical bonds have formed by the rare earth ions with the two ligands energy can be transferred from the ligand to the RE3+, and the excited spectra was very wide showing that energy transfer was efficient, the fluorescence emission intensity of 5 D0-->7 F2 transitions in the strongest according to the emission spectra of the complexes. So the authors choose this energy transition as the research object and the results showed that the emission intensity of Eu3+ ion can be enhanced if a part of Eu3+ ions were substituted by Y3+ or Tb3+ ions. But the concentration of the Y3+ or Tb3+ ions can influence the fluorescence emission intensity of the rare earth complexes. The authors changed the concentration of Y3+ and Tb3+ in order to find the proper proportion Finally the authors found that if the x < 0.3 for the complexes EuxY1-x (beta-NTA)3 phen can get higher fluorescence intensity than pure Eu3+ system, but compared with the concentration of Y3+, the proportion of Tb3+ is different. The result showed that if x < 0.5 the authors can get higher fluorescence intensity. In all, at a proper proportion of the doping ions (Y3+ or Tb3+) the authors can get higher fluorescence intensity. This doping method not only decreases the cost of materials, but also enhances the fluorescence intensity, so it has a bright future in practical application.