Visible-light photocatalysis in water provides an attractive green alternative to typical organic synthesis, which often involves toxic solvents, metal catalysts, and large energy demands. Hence, there is a growing need for efficient photocatalysts that operate in aqueous media. We envisioned that a supramolecular photocatalytic hydrogel provides a promising solution to this challenge as hydrogel can recruit hydrophobic molecules inside the nanofiber network, and, upon exposure to light, induce a chemical change that would otherwise not occur in water. Here, we report supramolecular photocatalytic hydrogels, composed of the organic chromophore diketopyrrolopyrrole (DPP) that assembles into supramolecular hydrogels upon in situ enzymatic hydrolysis. In our design, the catalyst itself acts as a gelator and thereby, provides a high density of photoactive sites. DPP molecules have been functionalized with three different amino acids (Y, F, or L) to modulate the supramolecular and photophysical properties of the assembly. Under visible light irradiation, these supramolecular hydrogels produce <sup>1</sup>O<sub>2</sub> which we have used to demonstrate the photooxidation of thioanisole and cyclohexyl methyl sulfide with yields as high as 100% and without over-oxidation. With our initial success, we have started to explore the application of our aqueous compatible supramolecular catalysts for other important photocatalytic organic reactions.

Visible-light photocatalysis in water by functional supramolecular hydrogels

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.