Electrostatic Coassembly Enables Sequential Energy Transfer and ROS Pathway Switching in Aqueous Artificial Light-Harvesting Systems.

Natural photosynthesis achieves efficient light-to-chemical energy conversion through precisely orchestrated multistep energy transfer and tightly regulated reactive intermediates. However, reproducing such functional integration in artificial systems, particularly in aqueous environments, remains challenging. Herein, we report an aqueous artificial light-harvesting system (ALHS) constructed via supramolecular electrostatic assembly that couples sequential energy transfer with programmable reactive oxygen species (ROS) regulation. Sulfonate-functionalized tetraphenylethylene derivatives with tunable charge densities were employed as aggregation-induced emission donors and coassembled with hyperbranched polyethylenimine, enabling tunable regulation of donor-acceptor interactions. Sequential incorporation of Sulforhodamine 101 (SR101) and Cyanine 5 (Cy5) afforded highly efficient two-step cascaded energy transfer in water, accompanied by pronounced antenna effects and stepwise fluorescence lifetime shortening. Increasing donor sulfonation markedly enhanced energy-transfer efficiency and triggered an energy-transfer-driven shift in ROS pathways. The optimized TPE-4SO3-@PEI + SR101 + Cy5 system selectively suppressed singlet oxygen while promoting superoxide anion radicals, enabling efficient photocatalytic cross-dehydrogenative coupling of P(O)H compounds with thiols in pure water under ambient oxygen, delivering yields of up to 93%. This work establishes a structure-assembly-function relationship for designing efficient light-to-chemical energy conversion systems in aqueous photocatalysis.