Variation of water exchange dynamics with ligand structure and stereochemistry in lanthanide complexes based on 1,4-diazepine derivatives
作者:Elisa M. Elemento、David Parker、Silvio Aime、Eliana Gianolio、Luciano Lattuada
DOI:10.1039/b818445c
日期:——
Complexes of Gd, Eu and Yb(III) have been prepared with a series of heptadentate ligands related to the parent complex AAZTA, based on the 6-methyl-6-aminoperhydrodiazepine moiety. For (RR) and (RS)-diastereoisomers of a di-glutarate ligand, solution NMR studies revealed the presence of two major species that undergo water exchange rates at Gd differing by a factor of six. Comparison of solution hydration states for Eu(III) complexes reveals that each complex possesses two bound water molecules. The absence of a good correlation of 1H NMR pseudo-contact shifts for Eu and Yb analogues is suggested to arise from a change in hydration state between Eu and Yb.
钆、铕和镱(III)配合物是用一系列与母配合物 AAZTA 相关的七价配体制备的,这些配体基于 6-甲基-6-氨基全氢二氮杂卓分子。对于二戊二酸配体的(RR)和(RS)非对映异构体,溶液核磁共振研究显示存在两种主要的物种,它们在钆处的水交换率相差六倍。对 Eu(III) 复合物的溶液水合状态进行比较后发现,每个复合物都有两个结合水分子。Eu 和 Yb 类似物的 1H NMR 伪接触位移没有很好的相关性,这是因为 Eu 和 Yb 之间的水合状态发生了变化。