Achieving regioselective C–H functionalization is a particularly difficult issue in organic chemistry when these C–H bonds have similar reactivity. Although significant progress has been made in regioselective C–H functionalization at one specific site, the tunable version of such processes is rarely documented. Here we describe a tunable meta- and para-selective C–H borylation of aryl and benzyl phosphonates, in which the regioselectivity can be switched by bifunctional ligands. A broad range of substrates are compatible and exhibit good to excellent regioselectivity under mild reaction conditions. Benzyl phosphonates can be conveniently transformed into styrene derivatives via Horner–Wadsworth–Emmons olefination. Gram-scale preparation and derivatization of borylated products demonstrate the important application of our method in synthetic chemistry. The orthogonality of two functional Bpin and phosphorylmethyl groups provides ample opportunity for increasing the diversity of styrene derivatives with precise site-control.

Efficient photocatalytic H₂O₂ production is a sustainable alternative to the anthraquinone process, yet designing photocatalysts with both high activity and selectivity is extremely challenging. Covalent organic frameworks (COFs) offer modular architectures and tunable electronic structures, but precise electronic modulation for maximizing H2O2 photosynthesis is rarely attained. Here we report a series of naphthalimide-based donor–acceptor COFs with systematically engineered cores. Among them, NDI–B–COF (benzene core) delivers an outstanding H₂O₂ yield of 11,025 μmol g⁻¹ h⁻¹ (with sacrificial agent), far surpassing its nitrogen- and triazine-core analogs. This performance stems from synergistic effects of an extended in-plane conjugation and a reduced core polarity, which collectively enhance charge separation, directional carrier transport, and *OH intermediate formation, thereby lowering the barrier for two-electron water oxidation. These findings establish a clear structure–property–activity correlation and offer a general strategy for developing highly efficient metal-free photocatalysts.