Three‐in‐One C2H2‐Selectivity‐Guided Adsorptive Separation across an Isoreticular Family of Cationic Square‐Lattice MOFs

Energy‐efficient selective physisorption driven C2H2 separation from industrial C2‐C1 impurities such as C2H4, CO2 and CH4 is of great importance in the purification of downstream commodity chemicals. We address this challenge employing a series of isoreticular cationic metal‐organic frameworks, namely iMOF‐nC (n=5, 6, 7). All three square lattice topology MOFs registered higher C2H2 uptakes versus the competing C2‐C1 gases (C2H4, CO2 and CH4). Dynamic column breakthrough experiments on the best‐performing iMOF‐6C revealed the first three‐in‐one C2H2 adsorption selectivity guided separation of C2H2 from 1:1 C2H2/CO2, C2H2/C2H4 and C2H2/CH4 mixtures. Density functional theory calculations critically examined the C2H2 selective interactions in iMOF‐6C. Thanks to the abundance of square lattice topology MOFs, this study introduces a crystal engineering blueprint for designing C2H2‐selective layered metal‐organic physisorbents, previously unreported in cationic frameworks.