An Ultramicroporous Hydrogen‐Bonded Organic Framework Exhibiting High C 2 H 2 /CO 2 Separation

Abstract The separation of C 2 H 2 /CO 2 is not only industrially important for acetylene purification but also great scientific challenge due to their very similar molecular size and physical properties. To address this difficulty, herein, we present an ultramicroporous hydrogen‐bonded organic framework (HOF‐FJU‐1) from tetracyano bicarbazole to separate C 2 H 2 from CO 2 by taking advantage of differences in their electrostatic potential distribution. This material possesses a suitable pore environment and electrostatic potential distribution fitting well to C 2 H 2 , thus showing extra strong affinity to C 2 H 2 (46.73 kJ mol −1 ) and the highest IAST selectivity of 6675 for C 2 H 2 /CO 2 separation among the adsorbents reported. The single crystal X‐ray diffraction reveals that the suitable pore environment in HOF‐FJU‐1 provides multiple C−H⋅⋅⋅π and hydrogen‐bonded interactions N⋅⋅⋅H−C with C 2 H 2 molecules. Dynamic breakthrough experiments demonstrate its outstanding separation performance to C 2 H 2 /CO 2 mixtures.