苯甲酸稀土(Eu,La)配合物的红外和荧光光谱研究

用氯化稀土与苯甲酸铵在水溶液中反应，合成了苯甲酸稀土（Ｅｕ，Ｌａ）三元固体系列配合物，其化学组成式为（Ｅｕ１－ｘＬａｘ）Ｌ３（其中Ｌ为Ｃ６Ｈ５ＣＯＯ－，ｘ＝０．０～１．０）。研究了它们的红外光谱和荧光光谱。由红外光谱数据表明，配合物中羧基的对称和反对称伸缩振动吸收峰发生了分裂，而且羧基伸缩振动随着Ｌａ３＋离子含量的增加发生了规律性的变化。荧光光谱实验结果表明，用不发光的Ｌａ３＋离子取代苯甲酸铕中部分Ｅｕ３＋离子可以提高Ｅｕ３＋离子的特征荧光发射强度。

Studies on the Infrared and Fluorescence Spectra of Europium Lanthanum-Benzoate Complexes

A series of mixed rare earth complexes of benzoic acid with europium and lanthanum were synthesized by the reaction of trivalent rare earth chlorides with ammonium benzoate in aqueous solution. Their composition is expressed with the general formula (Eu(1-chi)La(chi)) L3, where L = C6H5COO(-1), chi = 0.0-1.0. Their infrared and fluorescence spectra were investigated. The characteristic asymmetric (v(as)) and symmetric (v(s)) stretching vibrations of carboxyl group for rare earth complexes shift to lower frequency in comparison with sodium benzoate, and both the absorption bands show splitting. In addition, the difference between v(as) and v(s), deltav (120-125) cm(-1), is lees than that of sodium benzoate (deltav =137 cm(-1)). These situations show that the coordinating pattern of the carboxyl groups in the complexes is the form of chelation-bridging, therefore, it may be suggested that the rare earth (Eu, La) benzoates are a heteronuclear polymers. The dependence of the relative fluorescence intensity of the mixed rare earth complexes upon the content for La3+ ions was discussed. The results show that the emission intensity for Eu3+ ions can be greatly enhanced if a part of Eu3+ ions in europium benzoate were substituted by La3+ inos. When chi = 0.4, 0.5 or 0.7, the fluorescence intensity of the rare earth complexes can rise above 40%.