853130-40-2Relevant articles and documents
Gadolinium(III) complexes of dota-derived N-sulfonylacetamides (H 4(dota-NHSO2R) = 10-{2-[(R)sulfonylamino]-2-oxoethyl}-1,4, 7,10-tetraazacyclododecane-1,4,7-triacetic acid): A new class of relaxation agents for magnetic resonance imaging applications
Aime, Silvio,Botta, Mauro,Cravotto, Giancarlo,Frullano, Luca,Giovenzana, Giovanni B.,Crich, Simonetta Geninatti,Palmisano, Giovanni,Sisti, Massimo
, p. 588 - 603 (2007/10/03)
Four new ligands for lanthanide ions based on the H3do3a (= 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid) structure and bearing one N-sulfonylacetamide arm were synthesized, i.e., H4dota-NHSO 2R = 10-{2-[(R)sulfonylamino]-2-oxoethyl}-1,4,7,10- tetraazacyclododecane-1,4,7-triacetic acids 1a-e. A 15N-NMR study of the 15N-labelled Eu3+ complex of one such ligands, 1d, showed that the coordination of the N-sulfonylacetamide arm involves the carbonyl O-atom rather than the N-atom. The relaxometric properties of the corresponding Gd3+ complexes were investigated as a function of pH and temperature. These complexes have relaxivities in the range 4.5-5.3 mM -1 s-1, at 20 MHz and 25°, and are characterized by a single H2O molecule in their inner coordination sphere. The mean residence lifetime of this molecule is relatively long (500-700 ns) compared to other anionic complexes. The slow rate of H2O exchange can be justified by the extensive delocalization of the negative charge on the N-sulfonylacetamide arm. The long residence time of the coordinated H 2O allowed the observation of the effect of the prototropic exchange on the relaxivity. The study of the interaction between the complex [Gd(1e)]- and HSA revealed a weak affinity constant highlighting the importance of a localized negative charge on the complex to promote a strong interaction with the protein.