Engineering Intralayer Anisotropy in Covalent Organic Frameworks

Abstract Precise control of intralayer anisotropy in two‐dimensional covalent organic frameworks (COFs) remains a significant challenge in materials design. We address this through a mixed‐linker strategy using 8‐connected pyrene and triphenylamine monomers with 4‐connected ETTA to form 1D nanoribbons. These ribbons are longitudinally stitched by diamines of programmable lengths, enabling precise in‐plane anisotropy tuning. Shortening the linkers from biphenyl to phenyl (T‐COF‐2 → T‐COF‐1) induces compressive strain within the π‐conjugated backbone, enhancing π‐electron delocalization and boosting photogenerated charge carrier mobility by over fourfold. Consequently, T‐COF‐1 achieves a 93.81% conversion efficiency in visible‐light‐driven NADH (nicotinamide adenine dinucleotide) oxidation—a 4.26‐fold enhancement over T‐COF‐2—along with a 1.41% apparent quantum yield at 420 nm. Remarkably, T‐COF‐1 retains substantial activity under 650 nm near‐infrared light (14.67% conversion, 0.11% quantum yield), highlighting its potential for photodynamic therapy. This work establishes interchain covalent proximity as a design principle for rationally engineering high‐performance COF photocatalysts, with broad implications for solar energy conversion and biomedical applications.