Design, synthesis, and properties of olefin‐linked covalent organic frameworks modified by heck coupling reaction.

The covalent organic frameworks (COFs) with olefin linkages are attractive materials for nonlinear optics due to their small energy band gap and large π‐electron separation domain. In this paper, a post‐synthetic modification (PSM) by applying a heck coupling reaction on olefin‐linked COFs was applied for the first time to obtain five functionalized triazine‐based covalent organic framework materials. The synthesized materials were tested for their relevant photophysical and electrochemical properties, and their third‐order nonlinear optical properties were tested using the Z‐scan technique. The experimental results indicate that the post‐modified COF (W4‐2) exhibits third‐order nonlinear polarizability χ3 that is 1.51 times higher than the unmodified COF (W4). [ABSTRACT FROM AUTHOR]