Synthesis of two 3,5-disubstituted sulfonamide catechol ligands and evaluation of their iron(III) complexes for use as MRI contrast agents

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 rl values in water were substantially higher than those of typical six-coordinate iron(III) complexes. The rl values in plasma under the same conditions increased. The iron(III) complexes were administered to rats, and the kidney and liver signal intensities were measured by T-1-weighted MR imaging experiments.