Synthesis And Luminescence Study Of Europium (?) Complexes With New Phosphine Oxide Derivatives As Neutral Ligands

In this thesis, two series of novel phosphine oxide derivatives were designed and synthesized:?1? Pyridine derivatives or quinoline ring were introduced to the diphenyl phosphine oxide?L1^L4?, tuning the triplet energy levels of the ligands to match the 5D0 level of europium??? and thus improved the antennae effects for sensitizing Eu??? emissions;?2? Based on the results of series 1, the nitrogen atoms of compounds L1 and L2 were oxidized to prepared L5 and L6. The stability of the Eu??? complexes should be well improved via the synergetic coordination effect of P=O and N=O moieties. In order to further improve the synergetic coordination ability, methylene was introduced to form ligand L7.35 new ternary Eu??? compounds were synthesized, by using the phosphine oxide derivatives?L1-L7? as neutral ligands, 2-thenoyltrifluoroacetonate?TTA?, dibenzoylmethanate?DBM?, hexafluoroacetonate?HFAC?, 2-hydroxy-4-Methoxybenzophenone?BP? and nitrate?NO₃^-? as anionic ligands, respectively. These europium complexes were characterized by elemental analysis and single-crystal X-ray diffraction.The UV absorption and photoluminescence?PL? properties of the europium complexes were thoroughly investigated.?1? These europium complexes showed strong UV absorption in the range of 220³50 nm??>1×104 L mol-1 cm-1?;?2? The complexes displayed emissions typical of Eu³⁺ ion under excitation. Furthermore, the total photoluminescent quantum yields, lifetimes and triplet energy levels of the ligands were measured and carefully discussed. All the above results suggested that the phosphine oxide ligands could cooperative sensitize europium ion emissions efficiently;?3? The luminescence efficiencies of the complexes with the same phosphine oxide ligands decrease in the sequence of Eu?TTA?₃Lx > Eu?DBM?₃Lx > Eu?HFAC?₃Lx > Eu?NO₃?₃Lx > Eu?BP?₃Lx. Among them, Eu?TTA?₃?L₄?₂ displayed the highest photoluminescent quantum yield of up to 58.2%, showing that the phosphine oxide derivatives are potentially excellent sensitizers for europium??? luminescence.