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Updated: Feb 3, 2026
Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging
Published on: July 21, 2011
Mononuclear Lanthanide Complexes with 18-Crown-6 Ether: Synthesis, Characterization, Magnetic Properties, and
Lindley Maxwell1,2, Martín Amoza1, Eliseo Ruiz1
1Departament de Química Inorgànica i Orgànica and Institut de Recerca de Química Teòrica i Computacional , Universitat de Barcelona , Diagonal 645 , E-08028 Barcelona , Spain.
Abstract:
A family of lanthanide metal complexes with the general formula [Ln(H2O)3(18-crown-6)](ClO4)3 (Ln = TbIII, DyIII, ErIII, and YbIII) has been synthesized. Their magnetic properties have been characterized by direct- and alternating-current SQUID measurements and analyzed with the help of CASSCF-type calculations. The DyIII and YbIII compounds show slow relaxation of magnetization under an external magnetic field. Analysis of the dependence of the relaxation time with the temperature and external magnetic field reveals that the main contributions are the quantum tunneling and Raman relaxation terms, respectively. Analysis of the β electron density and electrostatic potentials indicates that the axial ligands (three water molecules) generate a relatively small repulsion, with the lanthanide electron density being the reason for the moderate magnetic anisotropy found in these systems.
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