Two stable 3D porous metal–organic frameworks with high performance for gas adsorption and separation

Abstract

Two porous MOFs, [NO₃][In₃OL₃]·4DMF·3H₂O (JLU-Liu18) and [CdL]·0.5DMF (JLU-Liu19), H₂L = pyridine-3,5-bis(phenyl-4-carboxylic acid), have been solvothermally synthesized and structurally characterized. Both of the two compounds possess a saturated coordination metal centre without open metal sites (OMSs) leading to remarkable thermal and water vapour stability. JLU-Liu18 displays a rare occurrence of 9-connected, trinuclear [In₃O(CO₂)₆N₃] secondary building units (SBUs) in a porous crystal, with high adsorption for small gases, especially CO₂ (129 and 400 cm³ g⁻¹ at 273 and 195 K, respectively, under 1 bar). It also performs with commendable selectivity for O₂ over N₂, and CO₂, C₂H₆, C₃H₈ over CH₄. JLU-Liu19 possesses outstanding performance for sieving small gases owing to its ultramicropores of 3.5 Å. Both of the two MOFs are promising materials for gas adsorption and purification.