Synthesis and luminescent properties of complexes of Eu(III) with 2-thienyltrifluoroacetonate, terephthalic acid and phenanthroline

This work reports the synthesis and luminescent properties of complexes of europium(III) with 2-thienyltrifluoroacetonate (HTTA), terephthalic acid (TPA) and phenanthroline (Phen), in the solid state. The new complexes were characterized by elemental analysis, infrared (IR) spectroscopy, scanning electronic microscopy (SEM) and thermal stability analysis. Both binuclear complex Eu-2(TPA)(TTA)(4)Phen(2) and polynuclear complex Eu(TPA)(TTA)Phen present better thermal stability than the mononuclear complex Eu(TTA)(3)Phen does. The formation of the binuclear/polynuclear structure of the complexes appears to be responsible for the enhancement of the thermal stability. The emission spectra show narrow emission bands that arise from the D-5(0) --> F-7(J) (J = 0-4) transition of the Eu3+ ion. The spectral data of the complexes Eu(TPA)(TTA)Phen and Eu-2(TPA)(TTA)(4)Phen(2) present only one sharp peak in the region of the D-5(0) --> F-7(0) transition indicating that only one Eu3+ ion species is present in each sample. In addition, the luminescence decay curves of the complexes Eu(TPA)(TTA)Phen and Eu-2(TPA)(TTA)(4)Phen(2) fit a single-exponential decay law. The values of quantum efficiencies of the emitting D-5(0) level for the complexes Eu(TPA)(TTA)Phen and Eu-2(TPA)(TTA)(4)Phen(2) are 29% and 28%, respectively. (C) 2007 Elsevier Ltd. All rights reserved.