Amidation, Esterification, and Thioesterification of a Carboxyl‐Functionalized Covalent Organic Framework

Three new post‐synthetic modification reactions, namely amidation, esterification, and thioesterification, were demonstrated on a novel highly crystalline two‐dimensional covalent organic framework (COF), COF‐616, bearing pre‐installed carboxyl groups. The strategy can be used to introduce a large variety of functional groups into COFs and the modifications can be carried out under mild reaction conditions, with high yields, and an easy work‐up protocol. As a proof of concept, various chelating functionalities were successfully incorporated into COF‐616 to yield a family of adsorbents for efficient removal of several contaminants in the water. Versatile platform: A novel highly crystalline two‐dimensional covalent organic framework (COF) bearing pre‐installed carboxyl groups is reported. The carboxylic acids enable facile post‐synthetic modification by amidation, esterification, and thioesterfication for introduction of virtually any functionality to the framework.