Analysis of the conformational behavior and stability of the SAP and TSAP isomers of lanthanide(III) NB-DOTA-type chelates.
Analysis of the conformational behavior and stability of the SAP and TSAP isomers of lanthanide(III) NB-DOTA-type chelates.
复制标题
DOI：
10.1021/ic2012843
复制
发表时间：
2011-09-05
影响因子：
4.6
通讯作者：
Woods M
中科院分区：
文献类型：
--
作者：
Tircso G;Webber BC;Kucera BE;Young VG;Woods M
控制大环Gd³⁺螯合物的水交换动力学是设计改进的磁共振成像（MRI）造影剂的一个关键参数，而选择螯合物的配位几何结构可能有助于实现这一点。单帽扭曲反棱柱（TSAP）的水交换动力学比单帽反棱柱（SAP）的更接近最优，这使得TSAP异构体在高弛豫率应用中更具优势。已经开发了两种体系，它们能够在1,4,7,10 - 四氮杂环十二烷 - 1,4,7,10 - 四乙酸（DOTA）型Gd³⁺螯合物中选择TSAP配位几何结构，这两种体系均基于大环硝基苄基环烯。在本文中，我们报道了对这些螯合物的稳定性和形成的研究。特别关注了螯合反应过程中两种区域异构体螯合物的产生。这两种区域异构体的区别在于硝基苄基取代基在大环的角上还是边上。这两种区域异构体的产生似乎源于溶液中配体的一种构象，据推测在这种构象中，悬垂臂位于大环平面的上方和下方。在中间体H₂GdL⁺螯合物形成过程中发生的构象变化导致硝基苄基取代基的位置不同，这取决于Ln³⁺从大环的哪一面接近配体。
Controlling the water exchange kinetics of macrocyclic Gd3+ chelates, a key parameter in the design of improved magnetic resonance imaging (MRI) contrast media, may be facilitated by selecting the coordination geometry of the chelate. The water exchange kinetics of the mono- capped twisted square antiprism (TSAP) being much closer to optimal than those of the mono capped square antiprism (SAP) render the TSAP isomer more desirable for high relaxivity applications. Two systems have been developed that allow for selection of the TSAP coordination geometry in 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-type Gd3+ chelates, both based upon the macrocycle nitrobenzyl cyclen. In this paper we report investigations into the stability and formation of these chelates. Particular focus is given to the production of two regioisomeric chelates during the chelation reaction. These regioisomers are distinguished by having the nitrobenzyl substituent either on a corner or on the side of the macrocyclic ring. The origin of these two regioisomers appears to stem from a conformation of the ligand in solution in which it is hypothesized that pendant arms lie both above and below the plane of the macrocycle. The conformational changes that then result during the formation of the intermediate H2GdL+ chelate give rise to differing positions of the nitrobenzyl substituent depending upon from which face of the macrocycle the Ln3+ approaches the ligand.
登录
查看更多内容
影响因子：
4.3
作者：
Rudovsky, J;Cígler, P;Muller, RN
通讯作者：
Muller, RN
影响因子：
4.3
作者：
Kotek, J;Lebdusková, P;Peters, JA
通讯作者：
Peters, JA
影响因子：
6.2
作者：
IRVING, HM;MILES, MG;PETTIT, LD
通讯作者：
PETTIT, LD
DOI：
10.1002/cber.19931260404
发表时间：
1993-04-01
期刊：
CHEMISCHE BERICHTE-RECUEIL
影响因子：
--
作者：
HOEFT, S;ROTH, K
通讯作者：
ROTH, K
影响因子：
4.6
作者：
Aime, S;Botta, M;Merbach, AE
通讯作者：
Merbach, AE