3D Ln-MOFs containing pentanuclear clusters exhibiting magnetic refrigeration and slow magnetic relaxation

Two isostructural lanthanide-based 3D metal-organic frameworks (Ln-MOFs), [Ln(5)(mu(3)-OH)(6)(TZI)(3)(DMA)(1.5)-(H2O)(9.5)].DMA [Ln = Gd (1) and Dy (2), H(3)TZI = 5-(1H-tetrazol-5-yl) isophthalic acid], have been synthesized and structurally and magnetically characterized. In 1 and 2, the pentanuclear clusters with mixed (mu(3)-OH)(mu(2)-carboxylate) bridges are connected into 1D chains by mu(2)-H2O bridges, and then these chains are linked into 3D structures by the TZI ligands. The magnetic study suggests that 1 shows significant cryogenic magnetocaloric effects (-Delta S-m = 41.3 J kg(-1) K-1, Delta H = 70 kOe, 2.5 K), whereas 2 exhibits slow relaxation of magnetization.