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

Abstract

This work reports the synthesis and luminescent properties of the terephthalic acid (TPA) and europium(III) (Eu(III)) with 2-thienyltrifluoroacetonate (HTTA) and trioctylphosphine oxide (TPPO), in the solid state. The new complexes Eu(TPA)(TTA)(TPPO) 2 and Eu 2(TPA)(TTA) 4(TPPO) 4 were characterized by elemental analysis, infrared spectroscopy, scanning electronic microscopy and thermal stability analysis. The complexes Eu(TPA)(TTA)(TPPO) 2 and Eu 2(TPA)(TTA) 4(TPPO) 4 present higher thermal stability than Eu(TTA) 3(TPPO) 2 does. And the formation of the binuclear/polynuclear structure of the complexes appears to be responsible for the enhancement of the thermal stability. The emission spectra present narrow emission bands that arise from the 5D 0– 7F J ( J = 0–4) transition of the Eu 3+ ion. The spectral data of the complexes Eu(TPA)(TTA)(TPPO) 2 and Eu 2(TPA)(TTA) 4(TPPO) 4 show only one sharp peak in the region of the 5D 0– 7F 0 transition indicating that only one Eu(III) ion species is present in each sample. In addition, the luminescence decay curves of the complexes Eu(TPA)(TTA)(TPPO) 2 and Eu 2(TPA)(TTA) 4(TPPO) 4 fit a single-exponential decay law. The values of quantum efficiencies of the emitting 5D 0 level for the complexes Eu(TPA)(TTA)(TPPO) 2 and Eu 2(TPA)(TTA) 4(TPPO) 4 are 26.4 and 25.6%, respectively.