Preparation and photoluminescent behaviors of bipyrimidine bridged dinuclear Eu (III) complexes and their PMMA polymer films

Abstract

Four bipyrimidine bridged dinuclear Eu (III) complexes of fluorinated β-diketones were synthesized and their photoluminescence behaviors in solution, solid powder state and poly(methylmethacrylate) (PMMA) films were investigated in detail. The results showed that Eu (III) complexes and their PMMA polymer films all exhibited strong characteristic emissions of the corresponding Eu (III) ion and highly monochromatic red emissions. According to the emission spectra and luminescence decay curves, the Judd−Ofelt intensity parameters (Ω2, Ω4), lifetime (τ) and quantum efficiency were calculated. Their high Ω2 values suggested that the Eu (III) ion was in a highly polarizable ligand field in these complexes. Meanwhile the proposed energy transfer mechanisms of these complexes were also investigated and analyzed. In their PMMA polymer films, the luminescent lifetimes, quantum efficiencies were increased significantly as compared to their precursor Eu (III) complexes. Especially, the PMMA@Eu2(TMPD)6⋅Bpm polymer film displayed the longest lifetime (τ = 0.946 ms) and highest quantum efficiency (ΦLn = 71.9%). These results suggested that photoluminescence behaviors of dinuclear Eu (III) complexes doped in PMMA polymer films had been improved remarkably.