A heteronuclear ZnGd complex as a potential contrast agent for magnetic resonance imaging

A new ligand H₃L, with internal compartments for allocating 3d metal ions and external donors to bind 4f ions, was synthesized and completely characterized. Reaction of H₃L with zinc(II) and gadolin ium(III) salts allows isolating the heteronuclear complex {[ZnGd(HL)(NO₃)(OAc)(CH₃OH)](NO₃)}∙6H₂O (1·6H₂O). The ability of 1·6H₂O to act as a magnetic resonance imaging (MRI) contrast agent was evaluated and this study shows that both the transversal and longitudinal relaxivities are quite high but the T₁/T₂ ratio of 7.9 indicates that it could have even greater potential as a T₂ contrast agent.