Two Analogous Polyhedron-Based MOFs with High Density of Lewis Basic Sites and Open Metal Sites: Significant CO 2 Capture and Gas Selectivity Performance

By means of modulating the axial ligand and adopting supermolecular building blocks (SBBs) strategy, two polyhedron-based metal–organic frameworks (PMOFs) have been successfully synthesized [Cu 6 (C 17 O 9 N 2 H 8 ) 3 (C 6 H 12 N 2 )(H 2 O) 2 (DMF) 2 ]·3DMF·8H 2 O ( JLU-Liu46 ) and [Cu 6 (C 17 O 9 N 2 H 8 ) 3 (C 4 H 4 N 2 )(H 2 O) 2 (DMF) 2 ]·3DMF·8H 2 O ( JLU-Liu47 ), which possess a high density of Lewis basic sites (LBSs) and open metal sites (OMSs). Since the size of axial ligand in JLU-Liu47 is smaller than that in JLU-Liu46, JLU-Liu47 shows larger pore volume and higher BET surface area. Then, the adsorption ability of JLU-Liu47 for some small gases is better than JLU-Liu46 . It is worthwhile to mention that both of the two compounds exhibit outstanding adsorption capability for CO 2 ascribed to the introducing of urea groups. In addition, the theoretical ideal adsorbed solution theory (IAST) calculation and transient breakthrough simulation indicate that JLU-Liu46 and JLU-Liu47 should be potential materials for gas storage and separation, particularly for CO 2 /N 2, CO 2 /CH 4, and C 3 H 8 /CH 4 separation.