Two Analogous Polyhedron-Based MOFs with High Density of Lewis Basic Sites and Open Metal Sites: Significant CO2 Capture and Gas Selectivity Performance.

Abstract

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 [Cu6(C17O9N2H8)3(C6H12N2)(H2O)2(DMF)2]·3DMF·8H2O (JLU-Liu46) and [Cu6(C17O9N2H8)3(C4H4N2)(H2O)2(DMF)2]·3DMF·8H2O (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 CO2 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 CO2/N2, CO2/CH4, and C3H8/CH4 separation.