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

Abstract

Two isostructural lanthanide-based 3D metal–organic frameworks (Ln-MOFs), [Ln₅(μ₃-OH)₆(TZI)₃(DMA)_1.5(H₂O)_9.5]·DMA [Ln = Gd (1) and Dy (2), H₃TZI = 5-(1H-tetrazol-5-yl)isophthalic acid], have been synthesized and structurally and magnetically characterized. In 1 and 2, the pentanuclear clusters with mixed (μ₃-OH)(μ₂-carboxylate) bridges are connected into 1D chains by μ₂-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 (−ΔS_m = 41.3 J kg⁻¹ K⁻¹, ΔH = 70 kOe, 2.5 K), whereas 2 exhibits slow relaxation of magnetization.