A Series of Lanthanide Metal–Organic Frameworks Based on Biphenyl‐3,4′,5‐tricarboxylate: Syntheses, Structures, Luminescence and Magnetic Properties

Abstract

AbstractA series of isostructural lanthanide metal–organic frameworks (MOFs) formulated as [Ln4(BPT)4(DMF)2(H2O)8]·(DMF)5·(H2O)3 {BPT = biphenyl‐3,4′,5‐tricarboxylate, Ln = Eu(1), Gd(2), Tb (3), Dy (4), Ho (5), or Er (6)} have beenhydrothermally synthesized and structurally characterized. X‐ray diffraction analysis reveals that these complexes are isomorphous and isostructural, and each forms a three‐dimensional structure possessing one‐dimensional channels filled with lattice and coordinated water and DMF molecules. They show framework dynamics upon dehydration and rehydration. When heated above 220 °C for four hours, the crystallinity of the as‐prepared hydrated materials degrades completely to the amorphous dehydrated phases, but the structure is restored upon rehydration. Photoluminescence measurements show that complexes 1 and 3 are highly emissive at room temperature with quantum yields of 14.4 % and 60.9 %, respectively, but the yields unexpectedly fall to 5.2 % and 32.6 % after thermal treatment. The recovery of the quantum yields upon rehydration indicates that guest molecules enhance the luminescence rather than quench it. Results of magnetic measurements indicate that all complexes display antiferromagnetic behavior.