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.