Separation and Characterization of the Two Diastereomers for [Gd(DTPA-bz-NH<sub>2</sub>)(H<sub>2</sub>O)]<sup>2-</sup>, a Common Synthon in Macromolecular MRI Contrast Agents: Their Water Exchange and Isomerization Kinetics
作者:László Burai、Éva Tóth、Angélique Sour、André E. Merbach
DOI:10.1021/ic048645d
日期:2005.5.1
demonstrated that the diastereomer ratio for Ln(III) DTPAderivatives (approximately 60:40) remains constant throughout the lanthanide series, in contrast to Ln(III) EPTPA derivatives, where it varies as a function of the cation size with a maximum for the middle lanthanides (DTPA(5-) = diethylenetriaminepentaacetate; EPTPA(5-) = ethylenepropylenetriaminepentaacetate). The interconversion of the two diastereomers
A ligand of Formula (I) is provided:
wherein A
4
represents a hydrogen atom, a nitro group, an amino group, a thiocyanato group, or —Z—Y, in which Z is a divalent linking group and Y is a group derived from a biocompatible molecule, with the proviso that when X is methylene, A
4
cannot be a hydrogen atom or a nitro group. A metal complex having the ligand is also provided and is useful as a blood pool contrast agent or a targeting contrast agent.
Rotational Dynamics Account for pH-Dependent Relaxivities of PAMAM Dendrimeric, Gd-Based Potential MRI Contrast Agents
作者:Sabrina Laus、Angélique Sour、Robert Ruloff、Éva Tóth、André E. Merbach
DOI:10.1002/chem.200401326
日期:2005.1
given field and temperature, the relaxivity increases from G5 to G7, and then slightly decreases for G9 (r1 = 20.5, 28.3 and 27.9 mM(-1) s(-1), respectively, at 37 degrees C, 30 MHz). The relaxivities show a strong and reversible pH dependency for all three dendrimer complexes. This originates from the pH-dependentrotationaldynamics of the dendrimer skeleton, which was evidenced by a combined variable-temperature