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

Separation of acetylene (C₂H₂) from carbon dioxide (CO₂) or ethylene (C₂H₄) 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, MB₁₂H₁₂(dpb)₂(termed as BSF-3 and BSF-3-Co for M=Cu and Co), for highly selective capture of C₂H₂. The high C₂H₂ capacity and remarkable C₂H₂/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-H^δ-...H^δ+-C equivalent to C-H ^δ+... H^δ--B). This new type of C₂H₂-specific functional sites represents a fresh paradigm distinct from those in previous leading materials based on open metal sites, strong electrostatics, or hydrogen bonding.