Two Lanthanide(III)Copper(II) Organic Frameworks Based on {OLn6} Clusters that Exhibited a Large Magnetocaloric Effect and Slow Relaxation of the Magnetization

Two new 3D lanthanide(III)copper(II) organic frameworks based on unusual {OLn6} clusters have been successfully synthesized and fully characterized. Crystallographic studies showed that the {OLn6} clusters acted as 12-connected nodes that were linked together by [CuL2] (H2L=3-hydroxypyrazine-2-carboxylic acid) moieties to construct an interesting 4,12-c net with the point symbol {436.630}{44.62}3. Magnetic studies revealed that these two isostructural heterometallic frameworks exhibited different magnetic properties, depending on the different anisotropies of the lanthanide spin carriers: Gd-Cu showed a large magnetocaloric effect, with an entropy change (-Sm) of 35.76Jkg-1K-1, which is one of the largest values in high-dimensional complexes, whilst Dy-Cu exhibited slow relaxation of the magnetization at low temperatures.