The three novel pyridine-containing 12-membered macrocyclic ligands 1-3 were synthesized. The coordinating arms are represented by three acetate moieties in 1 and 3 and by one acetate and two phosphonate moieties in 2. In all three ligands, the acetate arm in the distal position is substituted, with a benzyl group in 1 and 2 and with an arylmethyl moiety in 3. The relaxivities r(1p) (20 MHz, 25degrees) of Gd-III complexes are: GD .1, r(1p) = 8.3 mm(-1) s(-1); GD . 2, r(1p) = 8.1 mm(-1) s(-1); Gd . 3, r(1p) =10.5 mm(-1) s(-1). H-1-NMRD and O-17-NMR T-2 data show that Gd . 1 and Gd . 3 contain two H2O molecules in the inner sphere, whereas the presence of two phosphonate arms allows the coordination of only one H2O molecule in Gd-2. Interestingly, the exchange lifetime of coordinated H2O in the three complexes is similar in spite of the difference in the coordination number of the Gd-III ion (i.e., 9 in Gd . 1 and Gd . 3, and 8 in Gd . 2). H-1-Relaxometric measurements at different pH and in the presence of lactate and oxalate were carried out to get some insight into the formation of ternary complexes from Gd . 1 and Gd . 3. Finally, it was found that binding to human-serum albumin (HSA) of Gd . 1 and Gd . 2, though weak, yields limited relaxivity enhancements, likely as a consequence of effects on the hydration sphere caused by donor atoms on the surface of the protein.
Designing novel contrast agents for magnetic resonance imaging. Synthesis and relaxometric characterization of three gadolinium(III) complexes based on functionalized pyridine-containing macrocyclic ligands / S. Aime, E. Gianolio, D. Corpillo, C. Cavallotti, G. Palmisano, M. Sisti, G. Giovenzana, R. Pagliarin. - In: HELVETICA CHIMICA ACTA. - ISSN 0018-019X. - 86:3(2003), pp. 615-632.
|Titolo:||Designing novel contrast agents for magnetic resonance imaging. Synthesis and relaxometric characterization of three gadolinium(III) complexes based on functionalized pyridine-containing macrocyclic ligands|
PAGLIARIN, ROBERTO (Ultimo)
|Settore Scientifico Disciplinare:||Settore CHIM/06 - Chimica Organica|
|Data di pubblicazione:||2003|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1002/hlca.200390061|
|Appare nelle tipologie:||01 - Articolo su periodico|