Two Copper(II) Metal–Organic Frameworks with Nanoporous Channels and Vacant Coordination Sites

Two three-dimensional microporous compounds, Cu6(BTTC)4(H2O)6·xS (1) and [(CH3)2NH2]3[(Cu4Cl)3(BTTC)8]·yS (2, H3BTTC = benzo-(1,2;3,4;5,6)-tris (thiophene-2′-carboxylic acid), S represents noncoordinated solvent molecules), have been solvothermally synthesized and characterized, both of which are based upon truncated octahedron subunits and contain uniform nanosized cavities but exhibit different topological frameworks. Complex 1 demonstrates high adsorption enthalpies for H2 and CO2 gas molecules, stemming principally from the presence of the exposed metal Cu(II) sites on the pore surface. In particular, activated complex 1 shows high efficiency for the separation of energy-correlated molecules, including CO2 over N2 and CH4 under ambient conditions.