Synthesis of GdF_3 from the Gd_2O_3-NH_4HF_2 system

GdF3 was synthesized with Gd2O3 and NH4HF2 under atmospheric pressure and vacuum. The effects of pressure,temperature,and reactant ratio on the reaction process were investigated. A new mechanism for the synthesis of GdF3 was proposed. Powdered Gd2O3 started to react with NH4HF2 at low temperature,and the products were GdNH4F4,NH4F,NH3,and H2O. GdNH4F4 decomposed to GdF3 and NH4F after further high-temperature treatment,accompanying the volatilization and decomposition of NH4F. The whole process could be divided into three steps： synthesis,decomposition,and deamination. The initial and final reaction temperatures decreased under vacuum condition. An optimized process for the preparation of GdF3 was obtained： synthesis under atmospheric pressure at low temperature and decomposition and deamination under vacuum at high temperature.

多响应锆基金属有机框架荧光传感器对Fe^3+,Cr2O7^2-离子和有机小分子的识别

以2,2’,2"-[(1,3,5)-三嗪-2,4,6-三亚胺基]三苯甲酸(L)和ZrONO3·2H2O为原料,在N,N-二甲基甲酰胺(DMF)/H2O中合成了一种新的锆基金属有机框架荧光传感器(Zr-MOF).系统地研究了Zr-MOF对水溶中的Fe^3+和CrO3^2-离子的荧光响应,其猝灭常数(Ksv)分别为9.54×10^4,1.75×10^4 L·mol^-1,检测限(LOD)分别为3.78×10^-8,9.12×10^-7 mol/L.同时也研究了Zr-MOF对DMF溶液中的丙酮、CCl4和二甲苯的荧光识别,其猝灭常数(Ksv)分别为6534.3,4325.7,4025.1mL^-1,检测限(LOD)分别为1.09×10^-6,2.73×10^-5和3.17×10^-5 mL.通过FTIR、1H NMR、TAG、PXRD和元素分析等对Zr-MOF进行表征.结果表明,Zr-MOF在沸水和不同pH值溶液中,结构具有较高的稳定性,但其荧光强度在不同的pH值溶液中呈现一定的变化规律.水样和尿样检测证明,Zr-MOF可作为荧光传感器应用到实际溶液检测中.模拟实验表明,Zr-MOF对丙酮,CCl4和二甲苯有较高的选择性和灵敏度.