{Gd III 7 } and {Gd III 14 } Cluster Formation Based on a Rhodamine 6G Ligand with a Magnetocaloric Effect.

Heptanuclear {Gd III 7 } (complex 1 ) and tetradecanuclear {Gd III 14 } (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 Gd III ions via CH 3 O - /μ 3 -OH - bridges. Complex 2 has an unexpected three-layer double sandwich structure with a rare μ 6 -O 2- 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.