Accueil > Publications > Recherche par années > Années 2000 > 2007

Balogh, E ; Tripier, R ; Fouskova, P ; Reviriego, F ; Handel, H ; Tóth, E

Monopropionate analogues of DOTA4- and DTPA5- : kinetics of formation and dissociation of their lanthanide(III) complexes

Dalton Transactions (32) 3572-3581

par Administrateur - publié le

Abstract :

The replacement of an acetate function of the macrocyclic DOTA(4-) ( DO3A-Nprop(4-)) or the acyclic DTPA(5-) in terminal position ( DTTA- Nprop(5-)) has been recently shown to result in a signifi. cant increase of the water exchange rate on the Gd3+ complexes, which makes these chelates potential contrast agents for MRI applications. Here, two novel and straightforward synthetic routes to H(4)DO3A- Nprop are described. Protonation constants of DO3A- Nprop4- and stability constants with several alkaline earth and transition metal ions have been determined by potentiometry. For each metal, the thermodynamic stability constant is decreased in comparison to the DOTA chelates. The formation reaction of LnDO3A- Nprop(-) complexes ( Ln = Ce, Gd and Yb) proceeds via the rapid formation of a diprotonated intermediate and its subsequent deprotonation and rearrangement in a slow, OH- catalyzed process. The stability of the LnH(2)DO3A- Nprop* intermediates is similar to those reported for the corresponding DOTA analogues.