A 2D flexible cobalt-MOF: reversible solid-state structural transformation, two-step and gate-opening adsorption behaviours, and selective adsorption of C2H2 over CO2 and CH4

A new 2D flexible cobalt(ii) framework (Co-MOF) exhibits a reversible solid-state structural transformation upon guest molecule removal/uptake. After activation, Co-MOF-alpha with 1D porous channels transformed into Co-MOF-beta (0D voids) accompanied by a shift in metal and carboxylate coordination modes, the rotation of organic linkers and the contraction of interstitial spaces. Gas adsorption experiments reveal that Co-MOF-beta exhibits a two-step CO2 adsorption isotherm and close-to-open (type F-IV) isotherms for C2H2, C2H4 and C2H6 at 195 K. Moreover, it shows typical type I adsorption isotherms for the above gases and the selective uptake of C2H2 over CH4 and CO2 at room temperature.

Automated summary

A new 2D flexible cobalt(ii) framework (Co-MOF) undergoes reversible structural transformation upon guest molecule removal/uptake. After activation, Co-MOF-alpha with 1D porous channels transforms into Co-MOF-beta (0D voids) with changes in metal and carboxylate coordination modes, rotation of organic linkers, and contraction of interstitial spaces. Gas adsorption experiments reveal that Co-MOF-beta exhibits a two-step CO2 adsorption isotherm and close-to-open isotherms for C2H2, C2H4, and C2H6 at 195 K, demonstrating selective uptake of C2H2 over CH4 and CO2 at room temperature.