Layer-Distortion Engineering of Acridinium-Based Covalent Organic Frameworks Enables Efficient Photoredox Transformations of Alcohols

Abstract

Planar two-dimensional (2D) covalent organic frameworks (COFs) often suffer from severe interlayer π–π stacking, which promotes excitonic recombination, restricts access to active sites, and compromises photocatalytic efficiency. Here we report a layer-distortion engineering strategy to construct wavy acridinium-based COFs, Mes-Acr-TAPB and Mes-Acr-TAPP, by introducing structural distortion into otherwise planar layered frameworks. The resulting wavy framework efficiently suppresses interlayer π–π stacking, enlarges interlayer spacing, modulates molecular packing, pore environment, and improves accessibility to photoactive acridinium sites. Compared with the planar analog Dur-Acr-TAPB, Mes-Acr-TAPB exhibits enhanced exciton dissociation along with substrate absorption, more efficient charge separation, and superior photocatalytic activity. As a heterogeneous photoredox catalyst, Mes-Acr-TAPB enables diverse alcohol transformations under mild conditions, including β-scission radical functionalization, ring contraction/expansion, and skeletal transposition. Mes-Acr-TAPB shows broad functional-group tolerance and supports late-stage structural modification of complex natural products, highlighting its synthetic utility. This work establishes layer-distortion as an effective design principle for mitigating interlayer stacking in 2D COFs and advancing high-performance COF photocatalysts for sustainable organic synthesis.