Two GdIII complexes with different structures and magnetocaloric properties induced by metal ion sources

Two new GdIII complexes with the formulas of [Gd(ma)2(H2O)2]·2H2O (1) and {[Gd(ma)(ox)0.5(H2O)]·2H2O}n (2) (H2ma = DL-malic acid and H2ox = oxalic acid), have been successfully prepared by using Gd2O3 or Gd(NO3)3 as metal ion sources. Complex 1 exhibits a discrete mononuclear structure, while complex 2 displays a three-dimensional ‘layer-pillar’ structure with ox2- anions as pillars that generated in situ. Magnetic studies suggest the presence of ferromagnetic couplings between the intramolecular or interlayer GdIII ions and large magnetocaloric effects with −ΔSmmax = 32.1 J kg-1 K-1 (1) and 44.6 J kg-1 K-1 (2) under 7 T applied field. Therefore, they are good candidates as magnetic refrigerants.