Study On The Preparation And Property Of Rare Earth Europium, Terbium Organic Complexes

Rare earth organic complexes demonstrate potential applications in photoluminescence and electroluminescence due to their high quantum efficiency, sharp emission bands, low excitation energy, high absorption and adjustable molecular structure. So, in this paper, according to the design and cutting of organic molecules, the level matching principle and intramolecular energy transfer mechanism, four β-diketonate ligands and two aromatic carboxylic acid ligands and their Eu, Tb complexes were synthesized. The ligands and the complexes were characterized by elemental analysis, IR spectroscopy, UV-visible spectroscopy. phosphorescence spectra and fluorescence spectra. Furthermore, the complexes with better fluorescent properties were studied.The main works were as follows:Firstly, the novel β-diketone ligands1-(4-bromophenyl)-3-phenylpropane-1,3-dione,1-(4-bromophenyl)-4,4.4-trifluorobutane-1,3-dione,1-(4-aminophenyl)-3-phenylpropane-1,3-dion and1-(4-aminophenyl)-4,4.4-trifluorobutane-1,3-dione were synthesized at room temperature by classical Claisen condensation reaction. With the P-diketone as the first ligand and phen as the secondary ligand, rare-earth Eu, Tb binary and ternary complexes was prepared. The compositions of the complexes were RE(Ln)3·2H2O and RE(Ln)3phen(RE=Eu.Tb;n=1-4). The experimental results indicated that the luminescent properties of the complexes were mainly affected by the lowest triplet state energy of the first ligand. and the second ligand phen acted as the synergistic coordination or energy translater in different complexes. Moreover, the different luminous phenomena was explained by antenna effect, structure and coordinated ability of ligand. Dexter’s resonant exchange interaction theory and thermal deactivation mechanism.Secondly, the aromatic carboxylic acid ligands were synthesized at room temperature. With2-diphenylamine carbonyl benzoic acid and2-aniline carbonyl benzoic acid as the first ligand and imidazo[5.6-f] phenanthroline(IP) as the secondary ligand, new rare-earth Eu and Tb ternary complexes were prepared. The compositions of the complexes were RE(Ln)3phen(RE=Eu,Tb;n=5,6). Fluorescence spectra demonstrated that two kinds of ternary organic complexes could emit characteristic fluorescence of rare earth ions.The fluorescence intensities of two complexes were found to be influenced with the molecule structure, the benzene ring which was coordinated with nitrogen atom increased in2-diphenylamine carbonyl benzoic acid. In the system of ternary complexes, due to the different coordinated number of benzene ring, the mobility of electron and the distribution of electron cloud were changed. The variation affected the transition of the π electrons, which can absorb the energy in ternary complexes. So, the energy transfer efficiency from the first ligand to rare earth ions decreased and Antenna effect achieved inefficiency in the complexes.Finally, the rare earth complexes with stronger luminous intensity and better monochromaticity were choosen and their fluorescence properties were further characterized. The results showed that the fluorescence quantum efficiency and life time were congruously changed with luminous intensity, and the fluorescence properties of europium complexes with β-diketone and terbium complexes with aromatic carboxylic acid were better.