Nature Communications, Published online: 22 July 2026; doi:10.1038/s41467-026-75858-0 Extreme photoreduction is often limited by uncontrolled, diffusion-driven reactivity of highly energetic intermediates. Here, the authors report an association-gated photocatalytic strategy that assembles sequential donor–acceptor complexes to create confined reaction pockets, enabling selective activation of strong carbon–halogen bonds.