A metal–organic framework based on cyclotriphosphazene-functionalized hexacarboxylate for selective adsorption of CO 2 and C 2 H 6 over CH 4 at room temperature

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 C 2 H 6 , CO 2 and CH 4 gas isotherms. Furthermore, the activated ZJNU-60a displayed impressive adsorption selectivities toward C 2 H 6 and CO 2 over CH 4 , indicating the potential for the separation of CO 2 and C 2 H 6 from CH 4 . This is the first example of a MOF constructed from a flexible cyclotriphosphazene-functionalized hexacarboxylate for selective gas separation.