[Synthesis and fluorescence properties of the Tb(Ln) complexes with trimesic acid (Ln = Y, Gd)].

ABSTRACT

In the present paper two series of mixed rare earth complexes Tb(1-x)LnxBTC x nH2O (Ln = Y, Gd, x = 0, 0.1, 0.3, 0.5, 0.7, 0.9) were synthesized by hydrothermal method. The contents of rare earth were measured by using EDTA titration method; the element analyses of C and H were performed by using Vario EL III elemental analyzer, and the IR spectra were recorded by FTIR-8900 infrared spectroscopy with KBr pellet. Then the molecular formula of the complexes were determined to be Tb(1-x)LnxBTC x 0.5H2O (Ln = Y, Gd). The fluorescence spectrum of all the complexes were recorded by using a Hitachi F-4500 fluorescence spectrophotometer at room temperature. The results indicated that all the complexes emitted characteristic fluorescence of Tb3+, and the fluorescence intensities of the complexes were obviously enhanced with doping rare earth ion of Y3+ or Gd3+. It was showed that Tb3+ was sensitized by doping rare earth ions. This may be because there was intra molecular energy transfer in the complexes. Being doped with the rare earth ion the emission peak positions did not change. Among the four emission peaks, 5D4 --> 7F5 (544 nm) was the strongest one, and it was found when the proportion is Y3+ Tb3+ = 0.5 0.5 or Gd3+ Tb3+ = 0.3 0.7, the fluorescence intensity of Tb(1-x)YxBTC x 0.5H2O or Tb(1-x)GdxBTC x 0.5H2O was the greatest, meanwhile the sensitization degree was bigger with doping Gd3+ than doping Y3+ at 544 nm.