稀土与冠醚苯并15冠5配合物的稳定性研究  

Study on the complexes stability of lanthanides(Ⅲ) with B15-crown-5

作　　者：解凤霞[1] 张逢星[2] 吕余刚[2] 

机构地区：[1]西安工程科技学院环境与化学工程学院,陕西西安710048 [2]西北大学化学系,陕西西安710069

出　　处：《纺织高校基础科学学报》2005年第4期364-367,共4页Basic Sciences Journal of Textile Universities

摘　　要：用2-(2-噻唑基偶氮)-4-甲基酚(TAC,用L代表)作比色螯合剂,用苯并15冠5(B15C 5,用A代表)作竞争配体,通过分光光度竞争法,研究了无水乙醇中稀土金属离子Ln3+与B15C 5生成配合物的稳定性和稳定常数.首先由溶液的吸光度求得1∶1型配离子[LnL]3+的条件稳定常数K(LnL)’,接着在测试体系中逐渐加入竞争配体B15C 5,同时测定1∶1型配离子[LnL]3+的条件稳定常数K(LnL)",从1/K(LnL)"与B15C 5浓度的线性关系求出配合物[LnA]3+的稳定常数K(LnA),实验表明稳定常数K(LnA)随镧系稀土元素原子序数增加而减小.A spectrophotometer procedure using a colorimetric compliant has been used for the study of the complexation between lantbanides（Ⅲ） and B15-crown-5 （B15C5, A） in anhydrous alcohol. 2-（2-Thiazolylazo）-4-methylphenol （TAC, L） was used as a colorimetric complexant because of its simple structure with which no protonated complexes may be formed, The conditional stability constants of the [LnL]^3＋ complexes （K（LnL＇, K（LnL）＂） at constant acidity in the absence and the presence）of B15C5 were determined by monitoring the absorbance due to the [LnL]^3＋ complexes, The competition between TAC and B15C5 for the metal ion resulted in a decrease in K（LnL）＂ with increasing B15C5 concentration. From the dependence of 1/K（LnL）＂ on the concentration of B15C5 the stability constants of the [LnA]^3＋complexes could be determined, The stability constants of theses complexes were found to decrease with increasing anomic number. On the basis of the complexation trend observed, B15C5 was used as competitive ligand to increase the selectivity of chelating agents.

关 键 词：分光光度竞争法 稳定常数 稀土 苯并15冠5 

分 类 号：O657.32[理学—分析化学]