Distortable functionalized ligand implantation in ultra-microporous MOFs for efficient C2H2 purification

Abstract

Adsorption-based separation techniques are pivotal in the purification of C₂H₂, leveraging their eco-friendly and energy-efficient attributes. However, the reusability of adsorbents is highly restricted by the trade-off between adsorption capacity and adsorption enthalpy, which is required to be urgently addressed. Herein, we demonstrated that the implantation of distortable ligands with functional groups is efficient in solving the above issue. The functional groups provided binding sites for C₂H₂ adsorption, while the distortable ligands optimized the pore structures to reduce adsorption enthalpy, thus balancing the trade-off between adsorption capacity and enthalpy. A series of ultra-microporous MOFs was successfully constructed by employing different pyridine ligands. The adsorption capacity of SNNU-504 after optimization was effectively enhanced, while the adsorption enthalpy hardly increased due to the adjustable ligand torsion angle. Breakthrough experiments and GCMC simulations further verified the potential C₂H₂/CO₂ separation applications.