Abstract： Ten solid terbium complexes with 2-pyrazinecarboxylic acid （Hpyca） and butanedioic acid （BDAH） were synthesized via coprecipitation method and characterized by elemental, EDTA titration, inductively coupled plasma （ICP）, thermogravim- etry-differential scanning calorimetry （TG-DSC） and infrared （IR） analyses. The results showed that the complexes had the composi- tions of Tb（pyca）（BDA）·2H2O, Tb0.5Y0.5（pyca）（BDA）·2H2O, Tb0.5La0.5（pyca）（BDA）·3H20, Tb0.5Gd0.5（pyca）（BDA）·2H2O, Tb0.7Y0.3（pyca）（BDA）·3HO, Tb0.7Lao.3（pyca）（BDA）-0.5H20, Tb0.TGd0.3（pyea）（BDA）＇H20, Tb0.6Y0.4（pyca）（BDA）·2.5H20, Tb0.6La0.4 （pyca）（BDA）·2.5H2O and Tbo.6Gd0.4（pyca）（BDA）·3H20. IR spectra indicated that the rare earth ions coordinated with the carboxylic oxygen atoms of Hpyca and BDAH. Luminescence spectra showed that the doped La3＋, y3＋ or Gd3＋ ions did not affect the lumines- cence emission peak positions, but remarkably increased the luminescent intensities of terbium complexes. Furthermore, the doped lanthanide complexes showed longer luminescence lifetimes and higher quantum yields than pure terbium complex. The enhanced luminescence efficiencies of Tb3＋ ions in the doped complexes might result from the antenna effect of the two carboxylate ligands as well as the decrease of the self-quench of the Tb3＋ ions induced by the doped lanthanide ions.
Six kinds of terbium ternary complexes with halo-benzoic acids were synthesized. Their compositions were determined by C, H elemental analyzer and EDTA titration. The infrared spectra, ultraviolet absorption spectra, and fluorescence spectra were also measured to identify the complexes. Elemental analysis showed that the compositions of these complexes were Tb（p-BrBA）3- H20, Tb（p-CIBA）3- 2H20, Tb（p-FBA）3- H20, Tb（o-FBA）3·2H20, Tb（o-CIBA）3· H20, and Tb（o-BrBA）3. H20, respectively. The monodispersed Ag@SiO2 core-shell nanoparticles with silica thicknesses of 10, 15, and 25 nm were success- fully prepared and characterized by transmission-electron microscopy. Fluorescence intensities of the complexes were detected before and after Ag@SiO2core-shell nanoparticles were added; the enhancement times were related to the silica-shell thick- ness. The fluorescence enhancement times were largest when the thickness of the silica shell was 25 nm. The mechanism may be attributed to the localized surface-plasmon resonance. Furthermore, the enhancement effect of terbium fluoro-benzoate complexes was the strongest in these complexes. This result may be attributed to the hydrogen bond between the hydroxyl on the surface of the silica shell and the fluorine atom.
Dan ZhouXuemei LinAiling WangJingjing LiYanrong QuHaibin ChuYongliang Zhao
