Towards the rational design of MRI contrast agents: electron spin relaxation is largely unaffected by the coordination geometry of gadolinium(III)-DOTA-type complexes.
Electron-spin relaxation is one of the determining factors in the efficacy of MRI contrast agents. Of all the parameters involved in determining relaxivity it remains the least well understood, particularly as it relates to the structure of the complex. One of the reasons for the poor understanding of electron-spin relaxation is that it is closely related to the ligand-field parameters of the Gd(3+) ion that forms the basis of MRI contrast agents and these complexes generally exhibit a structural isomerism that inherently complicates the study of electron spin relaxation. We have recently shown that two DOTA-type ligands could be synthesised that, when coordinated to Gd(3+), would adopt well defined coordination geometries and are not subject to the problems of intramolecular motion of other complexes. The EPR properties of these two chelates were studied and the results examined with theory to probe their electron-spin relaxation properties.
Borel
Alain
A
Laboratoire de Chimie Inorganique et Bioinorganique, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland. alain.borel@epfl.ch
Bean
Jonathan F
JF
Clarkson
Robert B
RB
Helm
Lothar
L
Moriggi
Loïck
L
Sherry
A Dean
AD
Woods
Mark
M
D003287:Contrast Media / Q000138:chemical synthesis / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D004583:Electrons; D006571:Heterocyclic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D012015:Reference Standards; D013237:Stereoisomerism; D013696:Temperature
D003287:Contrast Media; D006571:Heterocyclic Compounds; D008024:Ligands; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate