Series of Highly Stable Lanthanide-Organic Frameworks Constructed by a Bifunctional Linker: Synthesis, Crystal Structures, and Magnetic and Luminescence Properties

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By utilizing a preselected functional ligand produced by 1 H -imidazole-4,5-dicarboxylic acid, three isostructural lanthanide coordination polymers (CPs), denoted as {[Ln 2 (OH) 2 (L) 2 ]·(DMF)·(H 2 O) 4 } n (Ln = Gd ( 1 ), Eu ( 2 ), Dy ( 3 ); L = 1-(4-carboxybenzyl)imidazole-4-carboxylic acid), containing a 1D infinite [Ln 4 (OH) 4 ] subchain have been successfully constructed. The highly connected mode between the multifunctional ligand and 1D building units is responsible for the exceptional chemical stability of three lanthanide CPs. In addition, a study of the magnetic properties reveals that 1 displays a large magnetic entropy change (−Δ S m = 30.33 J kg –1 K –1 with T = 2 K and Δ H = 7 T). Furthermore, genetic algorithm and quantum Monte Carlo methods were combined to simulate the magnetic coupling parameters of compound 1, shedding light on the effect of linking bridges on magnetic propagation. 2 shows intense luminescence in the range of 350–710 nm. Comparably, magnetic studies of 3 reveal the existence of a metamagnetic transformation from an antiferromagnetic interaction to a ferromagnetic interaction along with a decrease in temperature. Through fitting of the results of HF-EPR measurements, a component of the g tensor is obtained, g || = 16.4(5), indicating the large anisotropy of 3 .