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

Abstract

Two novel hexanuclear lanthanide complexes [Ln₆(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 β-diketonate salts Ln(acac)₃·2H₂O 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 {Ln₆} 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 (−ΔS_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.