The functional groups of the organic linker in ZIFs materials play an important role in the adsorption capacity and the selectivity of the materials (Figure ) . Adsorption properties of ZIF materials can be tuned via a mixed linker . ZIFs of a linker with electron-withdrawing and donating groups have enhanced CO2 adsorption . Density functional theory (DFT) calculation was used to quantify the binding ability of CO2 for ZIF materials for 137 linkers . The presence of asymmetrical functional groups, e.g., NO2/OH, CN/OH, and Cl/OH in imidazolate improved the CO2 adsorption . Amino-functionalized ZIF-8 materials using 2,5-diimidazolyl aniline (ZIF-DIA) exhibited superior CO2 adsorption . It can be used for CO2 capture in humid flue gas . Grand Canonical Monte Carlo (GCMC) simulations for ZIF-69 revealed that the electronegative -Cl functional group in the organic linker of ZIF-69 displayed an inductive effect.