A metal–organic framework based on cyclotriphosphazene-functionalized hexacarboxylate for selective adsorption of CO2 and C2H6 over CH4 at room temperature

Abstract

By using a flexible cyclotriphosphazene-functionalized hexacarboxylate, a novel metal–organic framework (ZJNU-60) has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. ZJNU-60 consists of dicopper paddlewheel secondary building units interconnected by organic linkers to form a bilayer with a rectangular channel running along the b axis. Upon desolvation, the framework underwent severe distortion and pore contraction, but the permanent porosity has been established as shown in C₂H₆, CO₂ and CH₄ gas isotherms. Furthermore, the activated ZJNU-60a displayed impressive adsorption selectivities toward C₂H₆ and CO₂ over CH₄, indicating the potential for the separation of CO₂ and C₂H₆ from CH₄. This is the first example of a MOF constructed from a flexible cyclotriphosphazene-functionalized hexacarboxylate for selective gas separation.