Synthesis and photoluminescence of three europium(III) ternary complexes with new secondary ligands of different structure

Three new 1,10-phenanthroline derivatives, dipyrido (3,2-f:2,3-h) quinoxaline (DPQN), imidazo (5,6-f)-(1,10)-phenanthroline (IP) and 3-phenyl-imidazo (5,6-f)-(l,10)-phenanthroline (PIP) were designed and synthesized as a secondary ligand to coordinate with europium(III) ion while dibenzoylmethane (DBM) was used as the first ligand. The compositions of the ligands and the europium(III) ternary complexes were confirmed by elementary analysis, IR and ¹H-NMR spectroscopy. The UV-visible absorption spectra, thermal stability, photoluminescence spectra, quantum yield and fluorescence life time of the Eu(III) complexes were investigated. The effect of the structure of the secondary ligand on the photoluminescence of the complexes was discussed. The results show that the synthesized Eu(III) complexes are good red-emitting materials for potential application in fabrication of organic electroluminescence devices.