Highly Water-Stable Zn₅ Cluster-Based Metal–Organic Framework for Efficient Gas Storage and Organic Dye Adsorption

The development of multi-functional materials as physical adsorbents for gas storage and dye adsorption is of utmost importance for ecological environment management. Ionic metal–organic frameworks (MOFs) with exchangeable counterions would easily be modified to enhance their performance. Herein, we report a novel {Zn₅}-based MOF (SDU-CP-2) with the dimethylamine cation [(CH₃)₂NH₂]⁺ in its crystal structure, which can be readily exchanged with Li⁺ ions and cationic dyes. Consequently, it exhibits high CO₂ and C₂H₂ adsorption capacities as well as charge/size-selective adsorption of dye molecules. The adsorption of SDU-CP-2 toward cationic dyes was confirmed to be efficient in terms of recyclability and ion-exchange mechanisms. The column filler experiment and high water stability decisively supported its potential application in waste water treatment.