Two linear-shaped Gd4 clusters based on a multidentate ligand: Synthesis, structures, and magnetic refrigeration

Abstract

Two novel and tetranuclear gadolinium clusters, namely, [Gd4(L)2(dbm)6(CH3OH)2] (1) and [Gd4(L)2(dbm)6(C2H5OH)2] (2) (H3L = (6-Hydroxymethyl)-N′-((2,3-dihydroxyphenyl)-methylene)picolinohydrazide and dbm = dibenzoylmethane), were assembled by the reaction of a multidentate ligand H3L with Gd(dbm)3·2H2O in different solvent system. Both the two Gd4 clusters have an approximate linear-shaped arrangement and the four central Gd3+ ions are connected by six μ2-O atoms. Direct-current (dc) magnetic susceptibility measurements of clusters 1 and 2 indicated that the weak antiferromagnetic interactions between adjacent Gd3+ ions both exist in clusters 1 and 2. It's particularly significant that clusters 1 and 2 display significant cryogenic magnetocaloric effects with maximum −ΔSm values of 21.39 and 20.26 J kg−1 K−1 at 2.0 K and 7.0 T, respectively.