Significantly Enhanced Carbon Dioxide Selective Adsorption via Gradual Acylamide Truncation in MOFs: Experimental and Theoretical Research.

A gradual amide truncation strategy was presented to tune the pore chemistry and CO2 capture performance of a series of tetracarboxylate-based Cu-MOFs. These MOFs exhibited a high density of Lewis basic sites (LBSs) and open metal sites and were prepared with the goal to enhance CO2 selective adsorption capacity. [Cu2(L1)(H2O)2]n (NJU-Bai42: NJU-Bai for Nanjing University Bai's group), [Cu2(L2) (H2O)2]n (NJU-Bai17), and [Cu2(L3)(H2O)2]n (NTUniv-60: NTUniv for Nantong University) were synthesized, and we observed that the CO2 adsorption capacities and MOF structures were impacted by subtle changes in ligands. Interestingly, although the NTUniv-60 was decorated with the least LBSs in these three MOFs, its CO2 adsorption capacity reached 270 (53.0 wt %) and 164 (32.2 wt %) cm3 g-1 at 273 and 296 K under 1 bar, respectively, which is the highest data reported for MOFs under similar conditions. From the grand canonical Monte Carlo (GCMC) simulation, the cooperative interactions between the CO2 molecules within the shuttle-shaped cages of NTUniv-60 could potentially explain why the CO2 uptake is high in this material.