Assembly of Solvent-Incorporated\nRod Secondary Building\nUnits to Ultramicroporous Metal–Organic Frameworks for Acetylene\nPurification

The process of industrial purification of acetylene (C<sub>2</sub>H<sub>2</sub>) is crucial yet challenging due to the similarities\nin physical properties and kinetic molecular sizes between C<sub>2</sub>H<sub>2</sub> and the impurity gases generated during its production.\nConventional distillation processes frequently result in significant\nenergy waste, highlighting the urgent need for more efficient separation\ntechniques. Metal–organic frameworks (MOFs), as a class of\nporous physical adsorbents, have demonstrated remarkable success in\nthe separation and purification of light hydrocarbons. By applying\nthe reticular chemistry approach, we have rationally designed and\nsynthesized two isoreticular compounds (named CoTPTA and MnTPTA) with\n novel low-valent {M–O–M} rod secondary building units\n(SBUs) based on the tetracarboxylic acid ligand H<sub>4</sub>TPTA\n([1,1′:3′,1″-terphenyl]-4,4′,4″,6′-tetracarboxylic\nacid). Both compounds displayed outstanding chemical stability when\nexposed to various organic solvents. In addition, a series of gas\nadsorption experiments demonstrated that they both have good C<sub>2</sub>H<sub>2</sub> purification ability. The adsorption selectivity\nwas subsequently verified by ideal adsorption solution theory (IAST),\nwhere the selectivity of CoTPTA for C<sub>2</sub>H<sub>2</sub>/CO<sub>2</sub> was 6.65 (v/v = 0.5:0.5).