四氮杂18-冠-6及其臂式衍生物对过渡金属离子的识别性能研究

Studies on the Recognition Properties of Tetraaza-18-Crown-6 and Its Armed-Derivatives to Transition Metal Ions

合成和表征了1,10-二氧-4,7,13,16-四氮杂18-冠-6(L1)母体及其两种乙酸乙酯臂式衍生物(L2、L3).采用pH电位滴定法测定了水溶液中3种冠醚配体与Hg2+、Cd2+、Mn2+、Zn2+、Co2+、Ni2+、Cu2+和Fe3+络合的稳定常数.设计编制了一种新的多元配合物稳定常数计算程序(QB-TITFIT2005),并对实验数据进行了拟合处理.用循环伏安法考察了水溶液中FeCl3及其配合物的电极反应行为.电位法测定的拟合结果表明,被测离子与3种冠醚均可形成1∶1的配合物,母体L1的配合物都有较高的稳定性,但选择识别性能较差;臂式冠醚L2、L3的配合物稳定性稍差,但对部分离子的选择性有所提高,且对Hg2+和Cd2+表现出较高的识别能力.循环伏安测定结果与此一致.

The parent azacrown ether 1,10-dioxa-4,7,13,16-tetraaza-18-crown-6 （L1） and its two acetic ester armed-derivatives（L2 and L3） were synthesized and characterized. The protonation constants of the macrocycle and the stability constants of their complex formation with Hg^2＋, Cd^2＋, Mn^2＋, Zn^2＋, Co^2＋ , Ni^2＋ ,Cu^2＋ and Fe^3＋ were determined in aqueous solution by potentiometry. A new computer program,QB -TITFIT2005, was developed in which stability constants of multicomponent complex can be determined by potentiometry. The data were processed by using the program. Electrode reactive behavior of FeCl3 and its complexes were investigated in aqueous solution by cyclic voltammetry. The results indicated that three kinds of crown ethers can form stable 1 ： 1 stoichiometric complexes with the transition metal ions. The parent azacrown ether L1 forms highly stable complexes with the cation, while its ability of selectively recognizing the cation was poor. The stability of the complexes of the armed-azacrown ethers L2 and L3 was poor, while their selectivity to some ions was increased, which has been attributed to the rigidity of the macrocycle. L2 and L3 display high selectivity to Hg^2＋ and Cd^2＋. The cyclic voltammetry measurements gave strong backing to the results obtained.