Ap(O2)-Responsive MRI Contrast Agent Based on the Redox Switch of Manganese(II /III) - Porphyrin Complexes

Different relaxation rates of water protons are enhanced by a contrast agent for magnetic resonance imaging (MRI). A supramolecular adduct of poly-β-cyclodextrin and [(MnII(tpps)]4− is described. Oxidation of the manganese center to MnIII causes a marked decrease in the observed relaxivity r1p (see scheme), which makes this a novel, functional MRI contrast agent for the measurement of partial pressures of oxygen. tpps=5,10,15,20-Tetrakis-(p-sulfonatophenyl) porphinate.