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

Abstract Two novel and tetranuclear gadolinium clusters, namely, [Gd 4 (L) 2 (dbm) 6 (CH 3 OH) 2 ] ( 1 ) and [Gd 4 (L) 2 (dbm) 6 (C 2 H 5 OH) 2 ] ( 2 ) (H 3 L = (6-Hydroxymethyl)-N′-((2,3-dihydroxyphenyl)-methylene)picolinohydrazide and dbm = dibenzoylmethane), were assembled by the reaction of a multidentate ligand H 3 L with Gd(dbm) 3 ·2H 2 O in different solvent system. Both the two Gd 4 clusters have an approximate linear-shaped arrangement and the four central Gd 3+ ions are connected by six μ 2 -O atoms. Direct-current (dc) magnetic susceptibility measurements of clusters 1 and 2 indicated that the weak antiferromagnetic interactions between adjacent Gd 3+ ions both exist in clusters 1 and 2 . It's particularly significant that clusters 1 and 2 display significant cryogenic magnetocaloric effects with maximum −Δ S m values of 21.39 and 20.26 J kg −1  K −1 at 2.0 K and 7.0 T, respectively.