Repairing Lattice Defects by an Orienting Strategy in a Porous Crystal: Boosting Inverse C₂H₆/C₂H₄ Separation

Defects are a common occurrence in various materials, making their repair a topic of widespread attention. However, the repair of atomic-scale lattice defects in porous crystals presents a substantial challenge. Herein, the repair of a linker-defective framework (NTU-70D) is presented through an orienting strategy to obtain a perfect framework (NTU-70P). Caused by steric hindrance from adjacent carboxylates of isonicotinic acid (INA), the lattice linker defect in NTU-70D is repaired by formic acid-assistant (pushed to the opposite direction by steric hindrance) installation of additional INAs in a defined direction, an unprecedented example in PCP chemistry. The resulting NTU-70P exhibits regular and smooth nano-channels that are adorned with more O_INA sites, leading to a significant increase in C₂H₆ uptake (51.0 to 90.2 cm³ g^-1) and C₂H₆/C₂H₄ selectivity (1.6 to 2.5), as evidenced by modeling calculations and in situ IR analysis. Furthermore, it demonstrates a notable ability to produce poly-grade C₂H₄ (with a record value of 46.4 mL g^-1) from C₂H₆-containing mixtures. This work presents the first example of repaired porous crystals for boosted inverse C₂H₆/C₂H₄ separation, and the insights gained into the lattice repair offer avenues for the development of rich defective systems in practical applications.