[Influence of La3+ on Eu3+ luminescence of three component complex system of europium-2-thiophene carboxylic acid-phen].

Seven solid complexes of proportional mixed complexes (Eu3+ mixed with La3+) of rare earth perchlorate with the 2-thiophene carboxylic acid and 1.10-phenanthroline were synthesized. By elemental analysis, coordination titration and molar conductance measurement, the composition of the complexes were suggested to be (Eu(1-x)La(x)) x L3 x phen x 1/2H2O (x = 0.000-0.200, L as 2-thiophene carboxylic acid and phen for 1.10-phenanthroline) respectively. The ligands and coordination compounds were studied by means of IR spectra and fluorescence excitation and emission spectra. The molar conductivities in DMF solvent suggested that the complexes are nonelectrolyte. IR spectra studies indicate that the 2-thiophene carboxylic acid ligands bonded with RE(II) through oxygen atoms in carboxyl group and 1.10-phenanthroline ligand is bonded to RE(III) through nitrogen atoms. In the fluorescence spectra it was found that the Eu3+ complex has no symmetrical center. La3+ has a great influence on the luminescence of Eu3+. The fluorescence emission intensity of Eu3+ was enhanced by La3+ and the fluorescence intensity with x = 0.050 is much higher. With La3+ concentration increasing the luminescence of Eu3+ is less intense.