[Synthesis and fluorescence properties of europium complexes with 4-(4-pyridyl formoyl) benzoic acid].

Three new europium complexes, Eu(PFBA)3 (H2O)4, Eu(PFBA)3 Phen (H2O)3 and Eu(PFBA)3 TPPO (H2O)3, were synthesized using 4-(4-pyridyl formoxyl) benzoic acid (HPFBA), 1,10-phenanthroline (phen) and triphenyl phosphine oxide (TPPO) as the ligands. In the complexes, two characteristic absorption bands of HPFBA due to vO-H (3 000-2 200 cm(-1)) and v c=o (1 697 cm(-1)) disappear, the asymmetry stretching vibration v(as)(coo-) and symmetry stretching vibration v(s)(coo-) of carboxyl appear, and the deltav(v(as)(coo)) - v(s)(coo-)) values are all smaller than that of NaPFBA. The carboxyl group of the ligand HPFBA is dehydrogenated and coordinated to Eu3+ with a bidentate chelating mode.