A Robust Adenine-Based Microporous Metal-Organic Framework with Hydrophobic Alkyl Groups and Abundant Lewis Basic...

The development of a chemically robust metal-organic framework (MOF) with appropriate pore nanospace for efficient CO₂ capture and separation from flue gas under humid conditions is sought after. Herein, an adenine-based microporous MOF, Cu-AD-SA, bearing abundant Lewis basic sites and alkyl groups has been utilized to capture and separate CO₂ from CO₂/N₂ gas mixtures. The introduction of alkyl groups enable Cu-AD-SA with high chemical stability. The confined pore nanospace involving small pore size and functionalized pore surface decorated by Lewis basic amino and alkyl groups bestows the framework with stronger CO₂ affinity versus N₂, thus resulting in a high CO₂/N₂ separation performance even at high operating temperature (323 K) and humidity (80%), as evidenced by breakthrough experiments. Moreover, molecular modeling studies were implemented to establish the adsorption mechanism, in which the ditopic aliphatic carboxylic acids and adenine linkers collaboratively play a vital role in the separation of CO₂/N₂ gas mixtures via C-H···O_CO, C_CO···O, C_CO···N, and C_CO···π interactions.