Inorganic Chemistry p. 7966 - 7979 (2011)
Update date:2022-08-25
Topics:
Tircso, Gyula
Webber, Benjamin C.
Kucera, Benjamin E.
Young, Victor G.
Woods, Mark
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.
View MoreSuzhou SuKaiLu Chemical Technology Co., Ltd.
Contact:+86-512-62766020
Address:Floor 4, Building 1, Xinyi Pharmaceutical Valley Wisdom Industrial Park, 415 Changyang Street, Suzhou Industrial Park, Jiangsu Province
Contact:86-25-58619180
Address:Nanjing High-Tech Zone 10 Xinghuo Road Pukou District Nanjing, Jiangsu 210061 The People's Republic of China
Contact:021-50278900
Address:No.6,Room 201 ,Lane 299,bisheng road ,shanghai ,china
MedicalChem(Yancheng)Manuf.Co.,Ltd.
Contact:+86-515-84383366
Address:Touzeng BinHai, YanCheng City, JiangSu Province, China
Contact:+86-571-87010026
Address:202, Zhenhua Road,
Doi:10.1002/ejoc.200500373
(2005)Doi:10.1248/cpb.21.2661
(1973)Doi:10.1002/ejoc.201701314
(2017)Doi:10.1039/c39900000923
(1990)Doi:10.1002/adsc.200600474
(2007)Doi:10.1016/j.tet.2019.05.015
(2019)