Structural and NMR Characterization of Sm(III), Eu(III), and Yb(III) Complexes of an Amide Based Polydentate Ligand Exhibiting Paramagnetic Chemical Exchange Saturation Transfer Abilities

Research into europium complexes as magnetic resonance imaging contrast agents (Review)

Europium (Eu) is a paramagnetic lanthanide element that possesses an outstanding luminescent property. Eu complexes are ideal fluorescence imaging (FI) agents. Eu²⁺ has satisfactory relaxivity and optical properties, and can realize magnetic resonance (MRI)-FI dual imaging applications when used with appropriate cryptands that render it oxidatively stable. By contrast, based on the chemical exchange saturation transfer (CEST) mechanism, Eu³⁺ complexes can provide enhanced MRI sensitivity when used with optimal cryptands, incorporated into polymeric CEST agents or blended with Gd³⁺. Eu complexes are promising in MRI-FI dual imaging applications and have a bright future.

Poly[diaqua-tris(μ(4)-isophthalato)dilanthanum(III)]

In the title coordination polymer, [La₂(C₈H₄O₄)₃(H₂O)₂]_n, there are two independent La^III atoms which are coordinated differently in slightly distorted penta­gonal-bipyramidal and slightly disorted bicapped trigonal-prismatic environments. The La^III ions are bridged by μ₄-isophthalate ligands, forming two-dimensional layers. In the crystal structure, these layers are connected by inter­molecular O—H⋯O hydrogen bonds into a three-dimensional network.