Triple Framework Interpenetration and Immobilization of Open Metal Sites within a Microporous Mixed Metal–Organic Framework for Highly Selective Gas Adsorption

A three-dimensional triply interpenetrated mixed metal–organic framework, Zn2(BBA)2(CuPyen)·Gx (M’MOF-20; BBA = biphenyl-4,4′-dicarboxylate; G = guest solvent molecules), of primitive cubic net was obtained through the solvothermal reaction of Zn­(NO3)2, biphenyl-4,4′-dicarboxylic acid, and the salen precursor Cu­(PyenH2)­(NO3)2 by a metallo-ligand approach. The triple framework interpenetration has stabilized the framework in which the activated M’MOF-20a displays type-I N2 gas sorption behavior with a Langmuir surface area of 62 m2 g–1. The narrow pores of about 3.9 Å and the open metal sites on the pore surfaces within M’MOF-20a collaboratively induce its highly selective C2H2/CH4 and CO2/CH4 gas separation at ambient temperature.