Construction of Chiral Covalent Organic Frameworks Through a Linker Decomposition Chiral Induction Strategy for Circularly Polarized Light Detection

Exploring new strategies for construction of chiral covalent organic frameworks (COFs) is of paramount importance yet remains a challenge. Herein, we report the rational design and construction of chiral COFs through a linker decomposition chiral induction (LDCI) strategy. Three pairs of azine-linked chiral COFs are successfully synthesized by the condensation reactions of C₃-symmetric 4,4′,4′′-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde (Tz) with flexible chiral dihydrazide linkers derived from malic acid, aspartic acid and tartaric acid, respectively. Remarkably, upon complete or partial decomposition from flexible chiral dihydrazides to hydrazine during COF synthesis, the homochirality of these COFs, originating from the single-handedness conformation of propeller-like Tz cores, is well preserved. Such a stereoselective chiral memory realized via the LDCI strategy is confirmed by time-dependent powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) and diffuse reflectance circular dichroism (DRCD). Moreover, the resultant azine-linked chiral COFs are used as the active materials to fabricate photodetectors to directly distinguish circularly polarized light (CPL), showing impressive recognition performances on the identification of left-handed circularly (LHC) and right-handed circularly (RHC) polarized lights. Notably, the residual undecomposed flexible chiral linkers within the COFs are found to be conducive to improving the polarization discrimination ratio. This work highlights LDCI as a new and effective strategy for constructing homochiral COFs with promising future in chiral optical application. © 2024 Wiley-VCH GmbH.