{Gd^III₇} and {Gd^III₁₄} Cluster Formation Based on a Rhodamine 6G Ligand with a Magnetocaloric Effect

Abstract

Heptanuclear {GdIII7} (complex 1) and tetradecanuclear {GdIII14} (complex 2) were synthesized using the rhodamine 6G ligand HL (rhodamine 6G salicylaldehyde hydrazone) and characterized. Complex 1 has a rare disc-shaped structure, where the central Gd ion is connected to the six peripheral GdIII ions via CH3O−/μ3-OH− bridges. Complex 2 has an unexpected three-layer double sandwich structure with a rare μ6-O2− ion in the center of the cluster. Magnetic studies revealed that complex 1 exhibits a magnetic entropy change of 17.4 J kg−1 K−1 at 3 K and 5 T. On the other hand, complex 2 shows a higher magnetic entropy change of 22.3 J kg−1 K−1 at 2 K and 5 T.

Keywords

• lanthanide oxygen cluster
• magnetocaloric effect
• magnetic refrigerant materials
• rhodamine ligand