Synthesis And Luminescence Study Of Novel Phosphine Oxide Neutral Ligands And Their Ternary Europium(Ⅲ) Complexes

In this paper, two series of novel phosphine oxide moiety modified neutral ligands were synthesized: the first series neutral ligands is based on diphenylamine framework; the second is based on benzimidazole framework. These novel neutral ligands have excellent charge transporting properties, enlarged conjugation planes and strong coordination ability. They show good synergistic antennae effect for sensitizing Eu3+ emission with anionic ligands(TTA). 1. Novel neutral ligands based on diphenylamine framework is shown as follow2. Novel neutral ligands based on benzimidazole framework is shown as followUsing the first series ligands based on diphenylamine framework(L1~L3) as the neutral ligands and 2-thenoyltrifluoroacetonate(TTA), dibenzoylmethanate(DBM),hexafluoroacetonate(HFAC), 2-hydroxy-4-methoxyacetophenone(AP), 2-hydroxy-4-methoxybenzophenone(BP) as the anionic ligands respectively, five series of total 15 new ternary europioum(III) complexes were synthesized; 2. Using the second series ligands based on benzimidazole framework(L4~L7) as the neutral ligands and TTA, DBM, BP, NO3- as the anionic ligands respectively, four series of total 16 new ternary europioum(III) complexes were synthesized. These complexes were charactered by elemental analysis and X-ray single crystal diffraction studies. Their photoluminescence properties were thoroughly studied by measuring the UV-Vis absorption spectra, emission spectra, quantum yields, lifetimes and the triplet state energy levels.The two series of novel neutral ligands have big absorption coefficient in the UV region. Furthermore, the triplet state energy levels of the second ligands match well with the emitting level of euripum(III) ion, and as a result the neutral ligands can efficiently sensitize euripum(III) emission with anionic ligands(TTA、DBM). Their ternary europioum(III) complexes exhibit intense red emission typical of Eu3+ at room temperature under the excitation around 300~420 nm. The quantum yield of TTA series complexes are the best with the highest quantum yield up to 41.0%, which are most likely to be used as red materials in electroluminescence(OLED). These ternary europioum(III) complexes with novel phosphine oxide derivatives as neutral ligands show better luminescence properties than that with TPPO as neutral ligands, suggesting that these novel neutral ligands are excellent sensitizers for Eu3+.