Judd–Ofelt treatment on luminescence of europium complexes with β-diketone and bis(β-diketone)

Abstract

Eu(DBM) 32H 2O and Eu 2(DDBM) 3H 2O were synthesized by reactions between EuCl 3 and chelating regents of β-diketone (dibenzoylmethane, HDBM) and bis(β-diketone) (1,3-bis(3-phenyl-3-oxopropanoyl)benzene, H 2DDBM), respectively, and their luminescence properties were investigated by the fluorescence spectra and metastable state decay spectra. It was found that the relative intensity ratio of 5D 0→ 7F 2 to 5D 0→ 7F 1transition and the radiative lifetime shows a little change attributing to the different symmetry of europium ions, which Ω 2 of Eu complexes with β-diketone and bis(β-diketone) are 13.08 and 12.24, respectively. Moreover, it was also found that the metastable state lifetime of Eu 2(DDBM) 3H 2O is much longer than that of Eu(DBM) 32H 2O, due to smaller water quenching and lower triplet level of ligands. The Commission Internacionale d’Éclairage (CIE) chromaticity coordinates calculated from emission spectrum are x=0.637 and y=0.343 for Eu 2(DDBM) 3H 2O, which presents high red color purity near 100%.