Charge‐Regulated Pyridinic Nitrogen in Covalent Organic Frameworks for Metal‐Free Heterogeneous Photocatalytic C─H Arylation of Pyrroles

Conventional catalytic systems for the C─H arylation of pyrrole predominantly rely on noble metals or organic dyes, which suffer from inherent limitations such as low sustainability, challenging recyclability, and high cost. To address these challenges, this study develops a metal-free photocatalytic strategy employing a designed covalent organic framework, N-TFPPy-BD-COF, as an efficient heterogeneous catalyst with a precisely tailored electronic structure. Site-specific nitrogen doping within the pyrene-based scaffold enables fine-tuning of the electronic landscape. Spectroscopic characterization and theoretical computations reveal that nitrogen doping facilitates spatial separation of photogenerated electron-hole pairs, suppresses recombination, thereby improves visible-light absorption, prolongs charge-carrier lifetimes, and enhances charge-separation efficiency. Under visible-light irradiation, the catalyst delivers outstanding performance in the arylation of pyrroles, affording a yield of 79% with 98% selectivity, surpassing those achieved by noble metal and organic dye-based systems. Furthermore, N-TFPPy-BD-COF exhibits remarkable stability as a heterogeneous catalyst, maintaining its structural integrity over ten consecutive catalytic cycles. This work not only presents a sustainable and efficient pathway for C─H arylation but also establishes a general strategy for the rational design of COF-based photocatalysts through electronic structure engineering.