Enhanced CH/CO Separation in a Microporous Hydrogen-Bonded Organic Framework Bearing Phenyl Cyanide-Based Electronegative Channels.

Separating acetylene (CH) from carbon dioxide (CO) is challenging due to the similarities in their kinetic diameters and physical properties. Common methods, such as size sieving and binding affinity in hydrogen-bonded organic frameworks (HOFs), have been applied to address this issue. Here, we report on an HOF, , which utilizes electronegative pore environments to selectively enhance CH affinity over CO. features a three-dimensional structure with a pore size of 5.38 Å and exhibits an S-shaped isotherm, achieving a record-high CH/CO uptake ratio of 4.8 at 273 K and 1 bar, showing a rare S-shaped curve for CH. Single-crystal X-ray diffraction analysis reveals a cyanide-based electronegative pore environment within that promotes multiple N···H-C hydrogen bonds and π-π interactions with CH molecules. Dispersion-corrected Density Functional Theory calculations indicate that the CH binding energy in is higher than that of CO. Additionally, exposure tests under harsh conditions confirm the chemical stability of , underscoring its robustness and potential for practical applications in CH/CO separation.