A Macrocycle‐Based Supramolecular Strategy for Interchangeable Screwdriver‐Like On‐Demand Post‐Functionalization of Covalent Organic Framework

Constructing functionalized covalent organic frameworks (COFs) through post‐functionalization constitutes one of the most important approaches to applications, but is frequently plagued by limited reaction types, tedious synthesis of different precursors, and time‐consuming screening of synthetic parameters for COFs. Moreover, their functions are difficult to change once the functionalities are covalently attached to COF skeletons. Herein, we report a macrocycle‐based supramolecular strategy for variable noncovalent post‐functionalization on the same COF platform like an interchangeable screwdriver. As a proof of concept, pillar[5]arene (P5A) with electron‐rich cavity is incorporated into COF as macrocycle host to anchor different electron‐deficient guests of various functions. Such a design allows tunable post‐functionalization of COF through host‐guest interactions for customized utilities, which has been demonstrated by using a series of guests including organic salts for iodine capture and cyano‐based ligands for metal ion separation. Removing the guests enables recycling of COF, consecutive reinstallation of different guests, and continuous use for implementing expected tasks. This work establishes a general noncovalent approach to on‐demand interchangeable post‐functionalization of COFs.