Luminescence properties and crystal structure of europium complexes with phenoxyacetic acid and 2,4,6-tri(2-pyridyl)-s-triazine

Using anion ligand phenoxyacetic acid (HPOA) and neutral ligand 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), two complexes Eu2(TPTZ)2(POA)6·6H2O and EuY(TPTZ)2(POA)6·6H2O have been synthesized and one crystal EuY(TPTZ)2(POA)6·2CH3OH has been obtained. These complexes are characterized by elemental analysis, ICP-AES, IR and UV absorption spectroscopy. The luminescence spectra, luminescence lifetimes and emission quantum efficiencies of the complexes have been studied. The results show that the complex EuY(TPTZ)2(POA)6·6H2O exhibits stronger luminescence intensity, longer luminescent lifetime and higher emission quantum efficiency than Eu2(TPTZ)2(POA)6·6H2O. The single-crystal X-ray diffraction of EuY(TPTZ)2(POA)6·2CH3OH reveals that the crystal is heteronuclear and crystallizes in the triclinic space group P-1 with following unit cell parameters a=12.2411(10) Å, b=13.2294(11) Å, c=13.5232(11) Å, α=74.8596(13)°, β=82.9593(16)°, γ=87.1641(14)°, and V=2097.7(3) Å3. Each metal ion coordinates with three nitrogen atoms of one TPTZ and seven oxygen atoms of three POA− ions. And there exist two coordination forms between POA− and metal ions in the crystal. One is chelating bidentate, the other is the single-atom bridge.