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Updated: Mar 19, 2026
Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging
Published on: July 21, 2011
Influence of Carboxylate Ligand Variation on Structure, Magnetic Exchange, and Magnetocaloric Performance in
Ondřej František Fellner1, Kamil Kotrle1, Erik Čižmár2
1Department of Inorganic Chemistry, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic.
Abstract:
Hexanuclear cyclic Gd(III) coordination compounds are promising candidates for magnetic and magnetocaloric applications, yet systematic series remain rare due to synthetic challenges. We report the synthesis and characterization of five new complexes with the general formula [Gd(H3bt)(carboxylate)]6, employing four different carboxylate coligands. Single‑crystal X‑ray diffraction confirmed their isostructural nature, with polymorphism observed in the 4‑bromobenzoate derivatives. Magnetic properties were investigated using SQUID magnetometry and complemented by Broken Symmetry DFT calculations. The study reveals weak antiferromagnetic exchange interactions and notable magnetocaloric performance, with entropy changes approaching 28 J K- 1 kg- 1 at 2.7 K (other compounds measured at 2 K) and 9 T. Magneto‑structural correlations based on structural parameters and substituent effects were established, providing guidelines for tuning exchange interactions in cyclic Gd(III) systems. Incorporation of a thioether substituent further suggests potential for surface deposition, opening pathways toward device‑oriented applications.
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