Immobilization of Lewis Basic Sites into a Quasi‐Molecular‐Sieving Metal–Organic Framework for Enhanced C₃H₆/C₃H₈ Separation

Abstract Controlling gas sorption through pore engineering is indispensable in molecular recognition and separation processes. The challenge lies in developing high‐efficiency adsorbents for C₃H₆/C₃H₈ separation, specifically enhancing the affinity toward C₃H₆ for high selectivity while maintaining a large gas uptake to obtain high separation efficiency. Herein, this problem can be addressed by controlling host‐guest interactions using Lewis basic sites modulation. A precise steric design of channel pores using an amino group as additional interacting sites enables the synergetic increase in C₃H₆ adsorption while suppressing the C₃H₈ adsorption, resulting in a quasi‐molecular‐sieving effect. Among them, TYUT‐23 has a perfect pore size that fits minimum cross‐sectional dimensions of C₃H₆, affording exceptional binding affinity for the C₃H₆ molecule. It adsorbs a large amount of C₃H₆ (2.5 mmol g⁻¹) and concurrently exhibits both remarkably high IAST selectivity (71) under ambient conditions. Equimolar C₃H₆/C₃H₈ breakthrough experiments also prove the prominent separation performance of TYUT‐23 for the production of high‐purity C₃H₆. The C₃H₆ adsorption/separation mechanism has been investigated using C₃H₆‐loaded single‐crystal structure analysis. This material demonstrates the potential of optimizing host‐C₃H₆ interactions using Lewis basic site modulation in industrial separations.