Microporous Metal-Containing Hydrogen-Bonded Organic Frameworks with Benchmark C2H2 Storage Density for Efficient C2H2/C2H4 and C2H2/CO2 Separations.

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.