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

Two fluorinated beta-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 (Omega(t)), lifetime (tau) and luminescence quantum efficiency (eta) were determined. The Omega(2) 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 (tau = 0.799 and 0.826 ms, respectively) and a higher luminescence quantum efficiency (eta = 56.5 and 56.1, respectively) among these complexes. (C) 2016 Elsevier Ltd. All rights reserved.