A flexible doubly interpenetrated metal–organic framework with gate opening effect for highly selective C2H2/C2H4 separation at room temperature

Abstract

A flexible metal–organic framework, {[Cu₂(TPPB)₂](DMF)₈}_n (1, H₂TPPB = 4,4′-((5-(4-(4H-1,2,4-triazol-4-yl)phenoxy)-1,3-phenylene)bis(oxy))dibenzoic acid, DMF = N,N-dimethylformamide), with a doubly interpenetrated network was solvothermally prepared by employing a flexible bifunctional triazolcarboxylate ligand. This MOF shows a dynamic structure with its network displaying different configurations by accommodating different solvents. More importantly, due to the synergistic effect of its suitable pore size and flexible structural feature, its activated phase demonstrates a significant C₂H₂ uptake capacity with stepwise and hysteretic sorption behavior, but only limited C₂H₄ is absorbed; this enables the discriminatory adsorption of C₂H₂ over C₂H₄. The separation potential of this flexible MOF towards C₂H₂/C₂H₄ is further established using IAST calculations of mixture adsorption equilibrium.