Adsorption and desorption of hydrogen from nanoporous materials, such as activated carbon, is usually fully reversible. We have prepared nanoporous metal-organic framework materials with flexible linkers in which the pore openings, as characterized in the static structures, appear to be too small to allow H ₂ to pass. We observe hysteresis in their adsorption and desorption kinetics above the supercritical temperature of H ₂ that reflects the dynamical opening of the “windows” between pores. This behavior would allow H ₂ to be adsorbed at high pressures but stored at lower pressures.

Separation of acetylene and ethylene is an important industrial process because both compounds are essential reagents for a range of chemical products and materials. Current separation approaches include the partial hydrogenation of acetylene into ethylene over a supported Pd catalyst, and the extraction of cracked olefins using an organic solvent; both routes are costly and energy consuming. Adsorption technologies may allow separation, but microporous materials exhibiting highly selective adsorption of C₂H₂/C₂H₄ have not been realized to date. Here, we report the development of tunable microporous enantiopure mixed-metal-organic framework (M′MOF) materials for highly selective separation of C₂H₂ and C₂H₄. The high selectivities achieved suggest the potential application of microporous M′MOFs for practical adsorption-based separation of C₂H₂/C₂H₄.