Flexible amorphous metal–organic frameworks with π Lewis acidic pore surface for selective adsorptive separations

Abstract

Selective separation of light hydrocarbons (LHs) and adsorption of volatile organic compounds (VOCs) remain expensive and complex scientific challenges in the petrochemical industry. Shape-selective adsorbent materials can cost-effectively face these demands. Two new porous, dynamic and amorphous metal–organic frameworks (MOFs), NEU-3 [= Zn(PMDA)(Py)₂] and NEU-4 [= Fe(PMDA)(Py)₂] are disclosed. These MOFs along with NEU-1c [= Zn(BPDI)(Py)₂] and NEU-2 [= Fe(BPDI)(Py)₂] display an electron-deficient pore surface due to predesigned π-electron-deficient ligands. They are unique smart guest-responsive materials owing to their π Lewis acidic pore surface and presumably their framework flexibility. A variety of effective adsorptions and adsorptive separations is achieved by using beds of NEU-1c, NEU-2, NEU-3 and NEU-4. Promising for further investigations into the petrochemical industry, NEU-4 shows ultrahigh benzene adsorption, recognition capability, selectivity for benzene over its analogues, and high stability and regenerability.