Tris(pyrone) chelates of Gd(III) as high solubility MRI-CA

Two tripodal, hexadentate pyrone-based chelators have been prepared. These ligands form stable, soluble complexes with gadolinium(III). The complexes show aqueous stability comparable to that of [Gd(DTPA)]^2- at pH 7.4. Evaluation by relaxometry shows that these complexes have two inner-sphere water molecules and a very fast water exchange rate. The solution behavior of these complexes suggests that they may be attractive as high relaxivity, next-generation magnetic resonance imaging contrast agents.