Synthesis and photoluminescent properties of Eu (III) complexes with fluorinated β-diketone and nitrogen heterocyclic ligands

• Six europium (III) complexes with the fluorinated β-diketones were synthesized.
• Photoluminescence behavior of europium (III) complexes were investigated.
• The Judd−Ofelt intensity parameter, lifetime and quantum yield were determined.
• Eu(TFPD)3⋅Bipy and Eu(TFPD)3⋅Phen exhibited a good photoluminescence behavior.

Two fluorinated β-diketones and their six europium (III) complexes using 2,2-dipyridine, 1,10-phenanthroline or 4′-phenyl-terpyridine as the secondary ligand were synthesized and characterized. The photoluminescence behavior for these complexes was investigated in solid state in detail. Based on the emission spectra and luminescence decay curves of these complexes in solid state, the Judd−Ofelt intensity parameters (Ωt), lifetime (τ) and luminescence quantum efficiency (η) were determined. The Ω2 values indicate that the europium (III) ion is in a highly polarizable chemical environment in these complexes. Europium (III) complexes with the secondary ligands 2,2-dipyridine or 1,10-phenanthroline exhibited much better photoluminescence properties than complexes with the secondary ligand 4′-phenyl-terpyridine. Especially, europium (III) complexes of 4,4,4-trifluoro-1-(4-fluorophenyl)-butane-1,3-dione containing the secondary ligands 2,2-dipyridine or 1,10-phenanthroline showed a longer lifetime (τ = 0.799 and 0.826 ms, respectively) and a higher luminescence quantum efficiency (η = 56.5 and 56.1, respectively) among these complexes.

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