Supramolecular dye polymers for aggregation-induced photocatalysis.

Aggregation can profoundly alter the excited-state properties of organic chromophores; however, crystalline supramolecular polymers are often targeted for photocatalytic conversion of solar energy due to favourable charge delocalization or exciton transport. Here we exploit aggregation as a strategy for organic chromophore rigidification to activate photocatalysis by stabilizing localized excited states. Using amphiphilic distyrylanthracene derivatives, we show that aggregation in water enhances the availability of excited states, enabling light-driven transformations of solar energy into storable fuels. We found enhanced reactivity to correlate with increased local excited-state population, underlining the role of self-assembly in restricting intramolecular motion and suppressing unproductive non-radiative decay. We observed photocatalysis to be maximized in kinetically trapped aggregates, outperforming their thermodynamic counterparts, to challenge conventional paradigm that favourable activities require extended assemblies. By achieving excited-state confinement and reactivity instead of charge delocalization, this work reports aggregation-induced photocatalysis as a strategy for preparing photostable, emissive and functional organic photocatalysts in water.