核磁共振法研究DTPA-BIN稀土配合物的溶液结构

Studies on the Solution Structures of Lanthanide(Ⅲ) Complexes of DTPA-BIN by NMR

用核磁共振方法研究了抗磁稀土配合物 Ln( DTPA-BIN) ( Ln=La,Y,Lu,Sc)的水溶液结构 . 1 H和1 3 C NMR谱的谱形特征表明 ,每一种配合物在水溶液中存在着两种以上不对称的异构体 ,异构体之间的差别较小 .并由 Y3+ 与 Gd3+ 离子半径的相似性推测出 Gd( DTPA-BIN)的溶液结构 ,即 DTPA-BIN分子提供 8个配位点 :3个骨架氮、 3个乙羧基氧及 2个酰胺氧 ,1个水分子占据另一个配位点 ,从而与 Gd3+ 形成了九配位结构 .

The solution structures of diamagnetic lanthanide(Ⅲ) complexes of DTPA\|BIN(Ln=La, Y, Lu, Sc) have been investigated by \{\}\+1H NMR, \{\}\+\{13\}C NMR and 2D NMR. For each complex, two or more species of asymmetric conformations with little distinction were identified at room temperature. And their solution structures vary with the radius of the central metals. NMR spectra support the hypothesis that Sc\+\{3+\} with smaller radius formed an eight\|coordinated structure with DTPA\|BIN, La\+\{3+\} with larger radius formed nine\| or ten\|coordinated structures with DTPA\|BIN, and Y(DTPA\|BIN) and Lu(DTPA\|BIN) had nine\|coordinated solution structures. The solution structure of Gd(DTPA\|BIN) was obtained from the similarity of radius between Gd\+\{3+\} and Y\+\{3+\}, which is a nine\|coordinated structure formed by three nitrogens, three acetate oxygens, two acetyl oxygens, one water molecule and a gadolinium(Ⅲ) cation.