A crystallographic study of new Cu(II) and Ln(III) complexes as contrast agents for MRI

Many efforts have been recently devoted to the search for heptadentate ligands able to give Gd (III)complexes for in vivo use as CAs for MRI as they have an increased relaxivity related to the possible presence of two coordinated water molecules. An efficient heptadendate ligand is the triaminotetracarboxylic AAZTA [1]. Its coordination geometry and the mutual disposition of donors atoms may offer useful information on the behaviour of CAs. The structure of the Na[Gd(H2O)AAZTA].3H2O [2] is known as well its associated magnetic properties but not those of the uncharged complexes. Here the structure of the neutral derivative [La(H2O)HAAZTA].4H2O is reported together with that of an other complex with the acyclic polyaminocarboxylate ligand EBTA [3] in its copper complex [Cu2EBTA(H2O)3]2 in order to understand its role in transmetallation reaction of the [GdEBTA]– complex.