Three Gd-Based Metal-Organic Frameworks Constructed from Similar Dicarboxylate Ligands with Large Magnetic Entropy Changes

Three Gd-based metal-organic frameworks with the formulas of {[Gd-2(suc)(3)(H2O)(2)]center dot H2O}(infinity) (1), {[Gd-2(fum)(3)(H2O)(4)]center dot 2H(2)O}(infinity) (2) and [Gd(glu)(ox)(0.5)(H2O)(2)](infinity) (3) (suc = succinate, fum = fumarate, glu = glutarate and ox = oxalate) have been hydro/solvothermally synthesized through the reaction of Gd2O3 and dicarboxylate ligands. Complexes 1 and 2 take three-dimensional (3D) structures derived from carboxylate-bridged chains, while complex 3 presents a Zigzag chain-based two-dimensional (2D) structure. All of them exhibit relatively good thermal stabilities. Magnetic investigations indicate that complexes 1 - 3 reveal weak magnetic interactions between the neighbouring Gd-III ions. Moreover, they display large magnetic entropy changes with - Delta S-m (max) reaching 42.22 J kg(-1) K-1 (1), 37.97 J kg(-1) K-1 (2) and 39.15 J kg(-1) K-1 (3) with Delta H = 7 T, respectively, indicating that they are promising cryogenic magnetorefrigerants.