Rational Design of Microporous MOFs with Anionic Boron Cluster Functionality and Cooperative Dihydrogen Binding Sites for Highly Selective Capture of Acetylene

Separation of acetylene (C₂ H₂ ) from carbon dioxide (CO₂ ) or ethylene (C₂ H₄ ) is important in industry but limited by the low capacity and selectivity owing to their similar molecular sizes and physical properties. Herein, we report two novel dodecaborate-hybrid metal-organic frameworks, MB₁₂ H₁₂ (dpb)₂ (termed as BSF-3 and BSF-3-Co for M=Cu and Co), for highly selective capture of C₂ H₂ . The high C₂ H₂ capacity and remarkable C₂ H₂ /CO₂ selectivity resulted from the unique anionic boron cluster functionality as well as the suitable pore size with cooperative proton-hydride dihydrogen bonding sites (B-Hδ- ⋅⋅⋅Hδ+ -C≡C-Hδ+ ⋅⋅⋅Hδ- -B). This new type of C₂ H₂ -specific functional sites represents a fresh paradigm distinct from those in previous leading materials based on open metal sites, strong electrostatics, or hydrogen bonding.