Enhanced optoelectronics properties of europium (Ⅲ) complexes with β-diketone and nitrogen heterocyclic ligands

摘要

Preparation and photoluminescence behavior of six new europium complexes with β-diketone 1-(2-hydroxy phenyl)-3-phenylpropane-1,3-dione (HPPP) and bath-ophenanthroline (batho), 2,2'-bipyridyl (bipy), 2,2'-biquinoline (biq), neocuproin (neo) and 1,10-phenanthro-line (phen) are reported in solid state. The ligand (HPPP) and complexes Eu(HPPP)_3·H_2O (1), Eu(HPPP)_3·phen (2), Eu(HPPP)_3·batho (3), Eu(HPPP)_3·bipy (4), Eu(HPPP)_3·biq (5) and Eu(HPPP)_3·neo (6) were characterized by means of elemental analysis, infrared spectroscopy, proton nuclear magnetic resonance (~1H-NMR). The optical properties, thermal stability and crystalline nature were investigated by photoluminescence spectroscopy, thermogravimetric analysis and XRD respectively. The emission spectra show narrow intense emission band of central europium (Ⅲ) metal ion that arise from the high intense ~5D_0 → ~7F_0 transition. The introduction of ancillary ligands like batho, bipy, biq, neo, phen enlarged the π-conjugation system in complexes as a result higher luminescence intensity, longer life time (τ) and higher quantum efficiency (η) observed in e.uropium ternary complexes in comparison to Eu(HPPP)_3·H_2O (1). Based on the emission spectra, the luminescence decay curve was measured which indicated that the transfer of energy from HPPP ligand to the europium metal is more efficient in complexes 2-6 than complex 1.