Pillar[5]arene-Mediated Assembly of Amphiphiles for Enhanced Light Harvesting and Photocatalysis

In nature, photosynthetic organisms such as cyanobacteria efficiently capture, transfer, and utilize solar energy in aqueous environments. However, replicating these processes in artificial supramolecular systems to achieve effective light harvesting and photocatalysis in water remains highly challenging. Here, we report a supramolecular light-harvesting system (LHS) constructed from a water-soluble dicarboxylate pillar[5]arene (H2), a triphenylacrylonitrile derivative (TPAN), and the acceptor dye 4,7-di(2-thienyl)benzo[2,1,3]thiadiazole (DBT). Structural optimization of the host enhanced the emission of the H2-TPAN supra-amphiphile by 2.5-fold compared with its fully carboxylated analogue (H1). The resulting ternary LHS exhibited excellent performance, enabling efficient generation of both singlet oxygen (¹O₂) and superoxide anion radical (O₂^•-). These reactive oxygen species (ROS) synergistically promoted metal-free oxidative amidation in water, affording methacetin and related derivatives in yields of up to 95%. This work demonstrates how rational supramolecular design can integrate fluorescence amplification, light harvesting, and dual-ROS generation into a single platform for efficient photocatalysis in aqueous media.