Modulating Acetylene Recognition in Boron Cluster Anion-Pillared Supramolecular Frameworks via Ligand Functionalization

Acetylene (C 2 H 2 ) and ethylene (C 2 H 4 ) are essential raw materials in the chemical industry, and producing them in high purity necessitates the efficient separation of C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 mixture─a challenging task due to their similar physical properties. Herein, we report the first example of a ligand-functionalized borane-cluster-based hybrid supramolecular metal–organic framework, denoted BSF-12, which integrates a hydroxyl-functionalized organic ligand (dpg) with inorganic boron cluster anions. This dual-functionalization strategy endows BSF-12 with exceptional adsorption and separation performance. The material exhibits high IAST selectivities of 12.0 for C 2 H 2 /CO 2 (50/50, v/v) and 11.7 for C 2 H 2 /C 2 H 4 (1/99, v/v), outperforming many previously reported high-performance adsorbents. BSF-12 demonstrates outstanding stability, maintaining its structural integrity after exposure to air and water for 10 days. Dynamic breakthrough experiments confirmed its practical separation capability and excellent cyclic stability. DFT calculations reveal that the synergistic cooperation between the functional hydroxyl groups from the dpg ligand and the hydride sites from the [B 12 H 12 ] 2– anion creates a robust recognition environment for C 2 H 2, driving its selective adsorption. This work establishes a new paradigm for the design of advanced boron cluster-based frameworks for key gas separations.