来源：ACS Publications
The reaction between isophthalic acid (H2L1) and Gd(NO3)3·6H2O leads to the formation of a two-dimensional (2D) extended framework with the molecular formula [Gd2(L1)3(H2O)2]n (1). Complex 1 crystallizes in monoclinic space group P21/n. The compound undergoes a reversible crystalline-to-amorphous phase transition. Magnetic susceptibility measurements on a polycrystalline sample of 1 reveal a weak ferromagnetic interaction between the Gd(III) centers below 20 K. Analysis of the magnetic data using the Fisher chain model indicates an exchange interaction strength (J) of +0.06 cm–1. A significant magnetic entropy change (−ΔSm) of 39.4 J kg–1 K–1 at 2.0 K and 9 T was observed, derived from detailed magnetization and heat capacity measurements on 1. The rate of change in the adiabatic temperature (ΔTad) was observed to be 2–3 K T–1. Further, to infer the porosity within 1, a N2 adsorption isotherm was conducted at 77 K, which indicates that the 2D sheets were held together strongly.
In this article, we report a Gd(III)-based 2D-sheet structure that is exclusively anchored by the isophthalate ligand with the repeating unit molecular formula as [Gd2(L1)3(H2O)2]n (1), which is characterized by single-crystal X-ray diffraction. To estimate the MCE parameters and to infer the porosity of 1, detailed DC magnetic susceptibility, heat capacity measurements and adsorption isotherms were performed, respectively, which are detailed below.