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

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.