Two hexanuclear lanthanide Ln6III clusters featuring remarkable magnetocaloric effect and slow magnetic relaxation behavior

Two novel hexanuclear lanthanide complexes [Ln(6)(L)(2)(acac)(6)(OH)(4)(NO3)(2)(CH3OH)(2)] (Ln = Gd (1), and Dy (2)) (Hacac = acetylacetone, H3L = N '-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl)picolinohydrazide) were prepared by reaction of polydentate Schiff base H3L and beta-diketonate salts Ln(acac)(3)center dot 2H(2)O via a solvothermal method. The structures of compounds 1 and 2 were determined by single-crystal X-ray diffraction analysis, and they both contain a {Ln(6)} cluster in the center. Their magnetic properties are investigated and the results indicate that 1 features a remarkable magnetocaloric effect with a maximum magnetic entropy change (-Delta S-m) value of 35.3 J kg(-1) K-1 at 7.0 T and 2.0 K, while compound 2 exhibits slow magnetic relaxation behavior.