Microporous Metal-Containing Hydrogen-Bonded Organic Frameworks with Benchmark C₂H₂ Storage Density for Efficient...

Separation of C₂H₂ 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 C₂H₂/CO₂ and C₂H₂/C₂H₄ 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 C₂H₂ molecule through hydrogen bonding. This endows the M-HOFs with excellent C₂H₂ capture capability, achieving a benchmark storage density of 396.0 mg cm^-3, while simultaneously demonstrating remarkable selectivity over C₂H₄ (420-97) and CO₂ (188-53). Breakthrough experiments confirm that binary gas mixtures can be efficiently separated by M-HOFs, where an impressive C₂H₄ productivity (137.4 mol kg^-1) is realized in the separation of C₂H₂/C₂H₄ (1/99), and an outstanding separation factor (17) is achieved for C₂H₂/CO₂ (50/50) splitting. Coupled with their superior chemical stability, these M-HOFs display tremendous potential for practical applications.