Preparation and fluorescent properties of europium (III) complexes with β-diketone ligand and 2,2-dipyridine or 1,10-phenanthroline

Abstract

The β-diketone ligand, 1-(4-methoxyphenyl)-3-phenylpropane-1,3-dione (MPPD), and its binary Eu(III) complexes Eu(MPPD)3, ternary complexes Eu(MPPD)3·Bipy with 2,2-dipyridine (Bipy) and Eu(MPPD)3·Phen with 1,10-phenanthroline (Phen) were prepared. The complexes were characterized with by elemental analysis, FT-IR, 1H NMR, UV–vis absorption, thermogravimetric analysis (TGA), ESI-MS and fluorescence spectroscopic techniques. TGA results showed that these complexes have good thermal stability. The emission spectra for complexes 2–4 exhibited the characteristic emission bands that arise from the 5D0→7FJ (J=0–4) transitions of the europium ion in solid state and chloroform solution. Based on the emission spectra in solid state, the Eu(III) ion could be sensitized efficiently by the ligands to some extent, in particular, in the ternary system, the secondary ligands Bipy and Phen acting as a light-harvesting center was involved in the highly efficient energy transfer process. In addition, the experimental intensity parameters, Ω2 and Ω4 were calculated from the fluorescence emission spectra. The radiative decay rate Arad, the nonradiative rates Anrad, the lifetime (τ) and the luminescent quantum yield (η) were determined and analyzed.