A Threefold Interpenetrated Pillared-Layer Metal–Organic Framework for Selective Separation of C2H2/CH4 and CO2/CH4

Abstract

A new threefold interpenetrated pillared-layer microporous metal–organic framework, [Zn2(cca)2(4-bpdb)]n⋅(DMF)2n (UTSA-85) (H2cca=4-carboxycinnamic acid, 4-bpdb=1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, and DMF=N,N-dimethylformamide), has been designed and generated by the solvothermal reaction of mixed ligands (H2cca and 4-bpdb) and Zn(NO3)2⋅6 H2O. Single-crystal XRD analysis disclosed that discrete paddle-wheel Zn2(COO)4 clusters as secondary building units linked the cca ligands to give two-dimensional layers, which were further pillared by 4-bpdb ligands to form a threefold interpenetrated pillared-layer structure. The desolvated framework, UTSA-85 a, was revealed to exhibit permanent porosity with a BET surface area of 558 m2 g−1 and a high selectivity of 64 for C2H2/CH4 separation at 296 K owing to the microporous (≈5.0 Å) structure and functional azine groups that decorated the pore channels.