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Torres, S ; André, JP ; Martins, JA ; Geraldes, CFGC ; Merbach, AE ; Tóth, E

Supramolecular assembly of an amphiphilic GdIII chelate : tuning the reorientational correlation time and the water exchange rate

Chemistry-A European Journal 12 (3) 940-948

par Administrateur - publié le

Abstract :

We report the synthesis and characterization of the novel ligand H(5)EPTPA-C-16 ((hydroxymethylhexade-canoyl ester) ethylenepropylenetriami-nepentaacetic acid). This ligand was designed to chelate the Gd-III ion in a kinetically and thermodynamically stable way while ensuring an increased water exchange rate (k(ex)) on the Gd-III complex owing to steric compression around the water-binding site. The attachment of a palmitic ester unit to the pendant hydroxymethyl group on the ethylenediamine bridge yields an amphiphilic conjugate that form s micelles with a long tumbling time (pi(R)) in aqueous solution. ne critical micelle concentration (cmc = 0.34 mm) of the amphiphilic [Gd(eptpa-C-16)(H2O)](2-) chelate was determined by variable-concentration proton relaxivity measurements.