Dodecanuclear [(Cu6Gd6III)-Gd-II] Nanoclusters as Magnetic Refrigerants

A novel dodecanuclear complex, [{(HL)(L)(DMF)(CuGdIII)-Gd-II(DMF)(H2O)}(6)]center dot 6DMF (1; DMF = N,N-dimethylformamide), has been obtained using the ligand resulting from the condensation of 3-formylsalicylic acid with hydroxylamine (H3L). The exchange interaction between the phenoxo-bridged Cu-II and Gd-III ions is weak ferromagnetic (J = +1.01 cm(-1)). The combination of a high-spin ground state with small anisotropy leads to a significant magnetocaloric effect [-Delta S-m(0-7 T) = 23.5 J K g(-1) K-1 at similar to 2 K].