Abstract
Efficient separation of C(2)H(2) from CO(2) remains a significant challenge owing to their closely matched molecular dimensions and physicochemical properties. Developing adsorbents capable of discriminating between these two gases is therefore of considerable importance for acetylene purification. Herein, we report two isoreticular two-dimensional covalent organic frameworks (COFs), TP-TFPB-COF and TP-NFPB-COF, featuring an hcb topology and constructed via [3 + 3] imine condensation. By increasing the fluorine content within the framework, TP-NFPB-COF exhibits enhanced C(2)H(2)/CO(2) separation performance, delivering an IAST selectivity of 2.86 at 298 K and 1 bar, compared with 2.04 for TP-TFPB-COF. Grand canonical Monte Carlo simulations reveal that the improved selectivity arises from increased pore polarity and strengthened C-H⋯F interactions with C(2)H(2) molecules. This work highlights fluorination as an effective strategy for tuning pore environments and advancing COF-based acetylene separation.