Intrinsic Flexibility of the Zeolitic Imidazolate Framework ZIF‐7 Unveiled by CO 2 Adsorption and Hg Intrusion

ZIF‐7, built as an assembly of Zn II centers and benzimidazolate ligands, shows prominent S‐shaped isotherms upon CO 2 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 CO 2 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.