Hydrogen-bonded ionic framework with ultrafine adaptive pores for selective gas adsorption

The development of hydrogen-bonded frameworks with both robust stability and adaptive functionality remains a significant challenge. Herein, we report a series of hydrogen-bonded ionic frameworks (HIFs) constructed via a supramolecular assembly strategy, utilizing bulky cationic Zn(II) coordination complexes and small inorganic anions. Directional charge-assisted hydrogen bonds effectively suppress close packing and yield robust architectures, with adaptive porosity under external stimuli owing to relatively weak interactions. Notably, HIF-23 exhibits a sophisticated guest-induced gate-opening effect, specifically triggered by the CO₂ with quadrupole moment. Comprehensive density functional theory (DFT) simulations and spectroscopic analyses reveal that the transition is driven by a localized conformational twisting of propane bridges and adaptive nature of the hydrogen-bonding network. The specific interaction with CO₂ enables high CO₂/CH₄ and CO₂/N₂ selectivity, complemented by a substantial high-pressure CO₂ capacity of 30.4 wt.% at 50 bar. This work underscores the potential of the HIF platform for the precision engineering of stimuli-responsive materials tailored for energy-efficient carbon capture.