均苯三甲酸铕及铕镧配合物的合成及荧光性质

以均苯三甲酸为配体,水热条件下合成了均苯三甲酸铕及铕镧系列发光配合物La_xEu_1-x(BTC)·nH₂O(x=0,0.1,0.3,0.5,0.7,0.9),通过元素分析及化学滴定法测定了配合物的组成。用红外光谱对其进行了表征,确定了该系列配合物的组成为La_xEu_1-x(BTC)·nH₂O。研究了系列配合物的荧光性质,荧光光谱表明:该类配合物均能发出强的铕离子的特征荧光,并且镧元素的掺入能增强铕配合物的发光强度,但发射峰的位置基本上没有变化;其中⁵D₀→⁷F₁和⁵D₀→⁷F₂的跃迁发射较强,且均劈裂为两个峰(587,593nm)和(611,618nm),这是由于铕离子所处的配位环境引起的。

Synthesis and Fluorescence Character of Eu (La) Complexes with Trimesic Acid

It is well known that aromatic acids serve as excellent ligands to effect sensitization of lanthanide fluorescence. 1,3,5-H₃BTC has three carboxylate groups and displays widely varying coordination manner, functioning as a monodentate, bidentate, bridging or chelating ligand in complexes with metal ions. On the other hand, the rare earth carboxylate complexes are the active area of research due to their fluorescence and application in high-teach industry, the application foreground is very fast. In recent years, there are many studies carrying on the carboxylate complexes in order to look for the good fluorescent materials, one of the major activities in these studies is the enhancement of fluorescence by using of certain rare earth ions,such as La³⁺,Y³⁺and Gd³⁺. The published dates on these were mainly focused on benzoic acid and benzene dicar-boxylate acid complexes, the complexes of trimesic acid with europium and lanthanum were comparatively scare. Only europium-trimesic acid fluorescence complexes were studied.Aseries of mixed rare earth complexes La_xEu_1-x(BTC)·nH₂O ( H₃BTC=1, 3, 5-H₃BTC, x=0, 0.1, 0.3, 0.5, 0.7, 0.9) have been synthesized by the reaction of trivalent rare earth chlorides with trimesic acid. The contents of rare earth, Cand Hwere measured by using EDTAtitration method and a Vario ELelemental analyzer, the constitution of these complexes was confirmed respectively as follows: La_xEu_1-x(BTC)·nH₂O (x=0, 0.1, 0.3, 0.5, 0.7, 0.9, n=0, 0.5,1.0).The IRspectra of free ligand and complexes were recorded by FTZR-8900 infrared spectroscopy with KBr pellet in the range of 350~3500 cm^-1. There is obviously difference between the ligand and complexes. The results show that the similar structures of the complexes and the different coordination functions of the carboxylate groups. Fluorescence spectra were carrying out by using a Hitachi F-4500 fluorescence spectrophotometer. The results indicate that the complex can emit intense characteristic fluorescence from europium ion, the emission peak centered at 578~582 nm (⁵D₀→7F₀),585~600 nm (⁵D₀→⁷F₁),605~630 nm (⁵D₀→⁷F₂),645~660 nm (⁵D₀→7F₃),685~700 nm (⁵D₀→7F₄), the intensity of the fluorescence of the series complexes were greater in⁵D₀→⁷F₁ and⁵D₀→⁷F₂, and both the positions show splitting emission peaks. These results show that the coordinating pattern of the carboxylate groups were different. In addition, the fluorescence intensities of europium ions were sensitized by the doping elements lanthanum ions, and the intensity of fluorescence is the best when La³⁺:Eu³⁺=0.3:0.7, but the position of the emission peak does not changed. In conclusion, a series of mixed rare earth complexes La_xEu_1-x(BTC)·nH₂O (x=0, 0.1, 0.3, 0.5, 0.7, 0.9) have been synthesized by hydrothermal treatment. They can emit strong fluorescence.