三种胺羧配合物的113Cd NMR研究

该文对Cd-HEDTA(N-(2-羟基乙基)乙二胺-N',N',N'-三乙酸),Cd-PDTA(1,2丙二胺四乙酸)和Cd-DTPA(二乙三胺五乙酸)的¹¹³Cd NMR谱和自旋晶格弛豫时间T₁,及NOE因子进行了研究.结果表明,Cd-HEDTA和Cd-PDTA结构与Cd-EDTA类似,Cd-PDTA双线归因于其可能的两种异构体.Cd-DTPA大的化学位移表明其具有七配位的五角双锥结构.在这种结构中DTPA可用三个氮原子参加配位.对¹¹³Cd自旋晶格弛豫时间分析表明,Cd-DTPA配合物中质子偶极作用机理的贡献较大,这归因于Cd DTPA有更多的乙酸根亚甲基质子参与偶极作用.

~113Cd NMR STUDIES OF THREE Cd-POLYAMINO-CARBOXYLIC ACID COMPLEXES

¹¹³Cd NMR spectra have been obtained on several Cd-polyaminocarboxylic acid complexes Cd-N-(2-Hydroxycthyl) ethylene diaminetriacetate (Cd-HEDTA), Cd-1,2-Propanediaminetetraacetate (Cd-PDTA) and Cd-Diethylenetriaminepentaacetatc (Cd-DTPA). The spectra revealed that Cd-HEDTA and Cd-PDTA have the same solution structure as the Cd-EDTA. The two lines of Cd-PDTA spectrum come from its two isomers and are indicative of the existance of more strained structure having the axial CH₃ group. The large chemical shift of Cd-DTPA shows that it is seven coordinated because in that case, three nitrogen atoms rather than two are bound to Cd atom. ¹¹³Cd nuclear Ovcrhauscr effect, η, and spin lattice relaxation time were determined for Cd-DTPA and Cd-HEDTA and used in the analysis of the contribution to the relaxation mechanism from the dipolar interaction with protons.