Cationic Covalent Organic Framework for Photocatalytic Defluorinative Amination of Fluoroarenes

Abstract

Abstract Covalent organic frameworks (COFs)—a unique class of crystalline, porous materials—are distinguished for their structural tunability, large surface area, high chemical stability, and tunable functionalities, which can be modified through pre‐ or post‐synthetic modifications. These features make COFs highly attractive platforms for heterogeneous photocatalysis and electrocatalysis. Building on these inherent advantages, we strategically modulated the electronic structure of a bipyridine‐based COF (Tp‐Bpy) via simple one‐step methylation to yield a dicationic, highly electron‐deficient framework (Tp‐Bpy‐Me). This post‐synthetic modification preserved the structural integrity of COF and introduced profound changes to its electronic environment, including a notable upward (positive) shift in the valence band position. Consequently, the cationic Tp‐Bpy‐Me COF exhibited an exceptional ability to activate one of the most inert bonds in organic chemistry, the C─F bond, under visible light irradiation. This study establishes Tp‐Bpy‐Me as a robust and efficient heterogeneous photocatalyst for defluorinative C─N bond formation across a broad range of substrates, including various fluoroarenes and nucleophiles. Remarkably, the photocatalytic transformation proceeds even under natural sunlight, highlighting its potential for sustainable, energy‐efficient applications. To the best of our knowledge, this work is the first successful demonstration of C─F bond activation toward C─N bond formation using a COF‐based photocatalyst.