Deciphering Dynamic Self‐Healing for Crystallinity Control in β‐Ketoenamine‐Linked Covalent Organic Frameworks

Abstract

ABSTRACT Covalent organic frameworks derived from triformylphloroglucinol (Tp‐COFs) represent a prominent branch of COFs due to their high potential in separation, energy storage, and optoelectronics. However, the development of Tp‐COFs is often hindered by limited crystallinity, resulting from the low reversibility of β‐ketoenamine bond formation. In this study, we report an unprecedented dynamic self‐healing mechanism during Tp‐COF formation, arising from a reversible Michael‐addition‐elimination (MAE) process. Building on this insight, a modulator‐mediated MAE pathway is further established for crystallinity control. As a representative example, Tp‐COF‐1 synthesized via this strategy (Tp‐COF‐1(H)) forms well‐defined columnar crystals with domain sizes up to 20 µm × 2 µm, and exhibits significantly improved structural order, as evidenced by a sharper powder x‐ray diffraction (PXRD) peak (full width at half maximum: 0.44° vs. 0.74°) and a higher specific surface area (1314 vs. 647 m 2 g −1 ), compared to Tp‐COF‐1 synthesized by the conventional method (Tp‐COF‐1(O)). Moreover, optical pump‐terahertz probe spectroscopy reveals a photoexcited charge‐carrier mobility of 10.84 cm 2 V −1 s −1 for Tp‐COF‐1(H), which is 1.77 times higher than that of Tp‐COF‐1(O). These findings identify dynamic self‐healing process via MAE as a key mechanism for governing Tp‐COF crystallization toward highly ordered Tp‐COFs for optoelectronic applications.