Two 3,5-disubstituted sulfonamide catechol ligands were synthesized. Tris(ligand) iron(III)complexes were prepared and investigated as MRI contrast agents. Longitudinal relaxivity(r1) values were determined for the complexes. The r1 values in water were substantially higherthan those of typical six-coordinate iron(III) complexes. The r1 values in plasma under thesame conditions increased. The iron(III) complexes were administered to rats, and the kidneyand liver signal intensities were measured by T1-weighted MR imaging experiments.
