Intrinsic flexibility of the zeolitic imidazolate framework ZIF-7 unveiled by CO2 adsorption and Hg intrusion

ZIF‐7, built as an assembly of ZnII centers and benzimidazolate ligands, shows prominent S‐shaped isotherms upon CO2 adsorption that can be attributed to sorbate‐induced gate‐opening phenomena involving a narrow‐to‐large pore phase transition. This peculiar sorption pattern can be captured via the formulation of thermodynamic isotherms, providing a direct enthalpic and entropic view of the gate‐opening process. Relying on such an approach, an energy barrier with preferential enthalpic nature for CO2 adsorption/desorption in the gate‐opening region could be unveiled. Moreover, the elastic energy involved during the gate‐opening process was revisited to 1.4–2.8 kJ mol−1 of solid in the temperature range 273–323 K, matching the value measured by isostatic compression of a ZIF‐7_lp sample filled with DMF and showing a dominant entropic contribution