Microporous Metal‐Containing Hydrogen‐Bonded Organic Frameworks with Benchmark C 2 H 2 Storage Density for Efficient C 2 H 2 /C 2 H 4 and C 2 H 2 /CO 2 Separations

Abstract Separation of C 2 H 2 from industrially important gas pairs using energy‐efficient adsorptive techniques with multifunctional porous materials remains a significant yet challenging issue. Here, we report the highly efficient separation of C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 mixtures with isostructural metal‐containing hydrogen‐bonded organic frameworks (M–HOFs), which feature micropore channels decorated with high‐density and uncoordinated carboxyl groups. Single‐crystal X‐ray diffraction analysis reveals that each free carboxyl group is capable of trapping one C 2 H 2 molecule through hydrogen bonding. This endows the M–HOFs with excellent C 2 H 2 capture capability, achieving a benchmark storage density of 396.0 mg cm −3 , while simultaneously demonstrating remarkable selectivity over C 2 H 4 (420–97) and CO 2 (188–53). Breakthrough experiments confirm that binary gas mixtures can be efficiently separated by M–HOFs, where an impressive C 2 H 4 productivity (137.4 mol kg −1 ) is realized in the separation of C 2 H 2 /C 2 H 4 (1/99), and an outstanding separation factor (17) is achieved for C 2 H 2 /CO 2 (50/50) splitting. Coupled with their superior chemical stability, these M–HOFs display tremendous potential for practical applications.