Substituent effects on Gd(III)-based MRI contrast agents: Optimizing the stability and selectivity of the complex and the number of coordinated water molecules

Heteropodal complexes, which include a terephthalamide (TAM) moiety and maintain the high relaxivity characteristics of the Hydroxypyridinone family, are functionalized with water-solubilizing moieties of different charge, which demonstrate high selectivity over physiological anions and cations. Results show that the charge of the substituent significantly affects the stability of the Gd(III) complex, with the most stable complex presenting a neutral charge.