New alkali earth metal–organic frameworks with a very high thermal stability: synthesis, crystal structure, and characterization of AE[NC5H3(CO2)2] (AE = Ba or Sr)

Abstract

Two new alkali earth metal–organic framework materials, AE[NC₅H₃(CO₂)₂] (AE = Ba or Sr), have been synthesized by solvothermal reactions using AE(OH)₂·8H₂O, 2,6-pyridinedicarboxylic acid, N,N-dimethylformamide, and water at 180 °C. The crystal structures of the reported materials were determined by single-crystal X-ray diffraction. AE[NC₅H₃(CO₂)₂] exhibits unprecedented three-dimensional framework structures that are composed of diamond-like alkali earth metal ring channels and the pyridinedicarboxylate organic linkers. Interestingly, AE[NC₅H₃(CO₂)₂] reveals very high thermal stabilities as demonstrated from TGA and powder XRD. Further characterization including infrared spectra, elemental analyses, and gas adsorption experiments is reported.