以4-氟苯甲酸(4-FBA)、4-氯苯甲酸(4-ClBA)为配体制备了具有良好热稳定性的稀土配合物Tb(4-FBA)3·2H2O和Tb(4-ClBA)3·2H2O, 与前期工作中合成的Tb(4-BrBA)3的紫外及荧光光谱进行了分析比较。紫外-可见光吸收光谱表明, 相同浓度下, 3种配合物的紫外吸收能力以Tb(4-FBA)3·2H2O、 Tb(4-ClBA)3·2H2O、Tb(4-BrBA)3顺序依次增大。液体荧光光谱表明, Tb(4-ClBA)3·2H2O的荧光发射强度最强。从配体的能级、配合物的紫外吸收能力及能量传递过程中的热振动损耗等方面对实验结果进行了讨论分析。热重分析表明, Tb(4-FBA)3·2H2O和Tb(4-ClBA)3·2H2O在450 ℃出现快速分解。将2种配合物放置于马弗炉中350 ℃加热1 h后, 发现Tb(4-FBA)3·2H2O的荧光发射强度降低了24%, Tb(4-ClBA)3·2H2O荧光发射强度仅降低了13%左右, 表明2种配合物高温条件下分子结构保持稳定, 加热后2种配合物的红外光谱也表明2种配合物在高温条件下未发生分解。

High-temperature resistant rare earth complexes Tb(4-FBA)3·2H2O and Tb(4-ClBA)3·2H2O were synthesized using 4-halogenated benzoic acids (4-fluorobenzoicacid and 4-chlorobenzoicacid) as ligands, respectively. They were characterized by the UV-spectra and fluorescent spectra and were compared with Tb(4-BrBA)3, which was synthesized by previous work. The UV spectra revealed that absorption intensities of the three kinds of terbium complexes Tb(4-FBA)3·2H2O, Tb(4-ClBA)3·2H2O and Tb(4-BrBA)3 in turn increased with the same molar concentration. The fluorescent spectra showed that the fluorescent intensity of Tb(4-ClBA)3·2H2O was the strongest. The relationship among energy level of the ligands, the ability of complexes absorbing UV energy and the non-radiative transitions was investigated for the experimental results. The thermal analysis indicated that Tb(4-FBA)3·2H2O and Tb(4-ClBA)3·2H2O started to lose weight around 100 ℃, suggesting the decomposition of crystal water and adsorbed water of the complexes, and the further mass loss around 450 ℃ belonged to the rapid decomposition of the complexes. When the two kinds of complexes placed in a muffle furnace were heated at 350 ℃ for 1 hour, it was disco-vered that the strongest fluorescence intensity of the Tb(4-FBA)3·2H2O reduced by 24% and Tb(4-ClBA)3·2H2O reduced by 13%. The IR spectra of the two kinds of complexes after heated showed that they did not decompose at high temperature.