Ultrastable amide-like isoquinolone-linked covalent organic frameworks for accelerated photocatalytic single-electron transfer transformation.

Abstract

The development of covalent organic frameworks (COFs) that integrate robust chemical stability with efficient charge carrier dynamics remains a critical challenge for photocatalytic applications. Herein, we present a self-locking strategy to synthesize amide-like isoquinolone-linked COFs (IQO-COFs). By leveraging ortho-vinyl aromatic aldehyde and aromatic amine precursors, a tandem process involving thermal 6π-electrocyclization of imine intermediates and Cu(OAc)₂-catalyzed aerobic oxidation enables the irreversible formation of rigid, conjugated isoquinolone linkages. Four crystalline IQO-COFs are constructed with high conversion efficiency and gram-scale feasibility. Locking amide into isoquinolone synergizes enhanced π-electron delocalization with structural rigidity, significantly suppressing exciton recombination and boosting photogenerated charge separation. As a result, IQO-COFs achieve high photocatalytic performance in single-electron transfer (SET)-driven reactions, including the dehalogenation of α-bromoacetophenone and the decarboxylative Minisci reaction under harsh conditions, outperforming amide-linked counterparts. This work establishes a versatile platform to engineer COFs with tailored stability and electronic properties, unlocking new potential for high-performance photocatalytic systems.