Supramolecular dye polymers for aggregation-induced photocatalysis

Aggregation can profoundly alter the excited-state properties of organic chromophores, yet its role in photocatalytic conversion of solar energy is typically associated with charge delocalization or exciton transport in crystalline supramolecular polymers. Here, we exploit aggregation as a strategy for rigidification of organic chromophores to activate photocatalysis by stabilizing localized singlet excited states. Using amphiphilic distyrylanthracene derivatives, we show that aggregation in water − triggered via concentration, charge screening, or counterion exchange − enhances fluorescence and enables light-driven transformations of solar energy into storable fuels, such as hydrogen (H2) and hydrogen peroxide (H2O2). Enhanced reactivity correlates with increased excited-state population, underlining the role of self-assembly in restricting intramolecular motion and suppressing unproductive non-radiative decay. The counterion dependence follows a reverse Hofmeister effect, with charge diffuse anions promoting aggregation, fluorescence, and photocatalytic function. Aggregated dyes also display enhanced photostability and recyclability compared to their molecular counterparts. Emission and catalytic activities are maximized in kinetically trapped aggregates, which outperform their thermodynamic counterparts, challenging conventional paradigm that photocatalysis is favored in extended assemblies. Finally, the dye aggregation-induced rigidification for photocatalysis is validated in a structurally distinct chromophore, confirming that the generality of the phenomenon. By achieving excited-state confinement and reactivity instead of charge delocalization, this work reports aggregation-induced photocatalysis (AIP) phenomena, with supramolecular packing as a powerful strategy for preparing photostable, emissive, and functional organic photocatalysts in water.