Synthesis of amine-functionalized ZIF-8 with 3-amino-1,2,4-triazole by postsynthetic modification for efficient CO₂-selective adsorbents and beyond

The facile tuning of the gate size and the chemical functionalization of zeolitic imidazolate frameworks (ZIFs) have been considered efficient strategies for various potential applications including gas membranes, sensors, and catalysts. Herein, we demonstrate the synthesis of amine-functionalized ZIF-8 (ZIF8-A) with 3-amino-1,2,4-triazole (Atz) by postsynthetic modification (PSM) towards two objectives: (1) CO₂ selective adsorption by a combination of chemical interactions and controlled gate sizes and (2) potential for further chemical modifications. The acquired ZIF8-A substantially enhanced CO₂/N₂ and CO₂/CH₄ selectivity at 35 °C compared to ZIF-8 since the Atz conversion enhanced chemical interactions with CO₂ due to the introduction of amine moieties while reducing both the surface area and pore volume. The gate size control of ZIF-8 by the replacement of Atz was thoroughly investigated by extensive transport experiments and density functional theory (DFT)-based computational simulations. In addition, the vinyl-functionalized ZIF-8, another versatile starting material, was successfully prepared by further chemical modifications of ZIF8-A with either methacrylic anhydride or glycidyl methacrylate through nucleophilic substitution reactions. As such, we believe that our current work can provide promising platforms for designing ZIF-based materials with versatile properties including precise control of the gate size and the incorporation of various functional groups.