Rationally engineering a photocatalyst to deliver high, controllable selectivity in CO₂ reduction (CO₂RR) is crucial for addressing global energy challenges. However, in organic supramolecular systems, this control is difficult due to the lack of well-defined coordination sites to stabilize intermediates. Here, inspired by induced-fit mechanisms of aromatic π-box pockets in natural proteins like Escherichia coli maltose-binding protein, we demonstrate organic supramolecular photocatalyst design by embedding scalable biomimetic pockets in two one-dimensional supramolecular coassemblies (TA-1DCA and BE-1DCA), which exhibit dynamic self-adaptive behavior to fit mutative C1 intermediates, achieving high and controllable selectivity between CO and CH₄ in CO₂RR. The scalable biomimetic pockets of the 1DCAs are constructed through cation-π-directed coassembly of large triangular-prism cages and a three-armed triazine cation. Thanks to the strong adaptability of cation-π interactions, coupled with the cooperative expansion and contraction of the large molecular cages, the positioning and flipping orientations of the aromatic cations around the pockets dynamically adjust to accommodate substrates of varying sizes and electronic environments. This enables the assembly to effectively stabilize distinct CO₂RR intermediates, guiding the proton-coupled electron transfer process toward a single reaction pathway. Specifically, TA-1DCA’s triazine-rich pocket donates electron density, locks *CO, and completes the eight-electron reduction to CH₄ with 95.8% selectivity and >90 μmol g^–1 h^–1. Lacking these donors, BE-1DCA fails to retain *CO, releasing it instead and giving 79.9% CO at ～67 μmol g^–1 h^–1.

（全文链接：https://doi.org/10.1021/jacs.5c18074）