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This article describes the synthesis and characterization of a UV-crosslinked Eosin Y-photocatalytic gel and studies its performance in the oxidation of thioanisole in batch and flow reactors. 

Abstract Heterogeneous photocatalysis combines the benefits of light‐mediated chemistry with that of a catalytic platform that facilitates re‐use of (often expensive) photocatalysts. This provides significant opportunities towards more economical, sustainable, safe, and user‐friendly chemical syntheses of both small and macromolecular compounds. This contribution outlines recent developments in the design of heterogenous photocatalysts and their use to mediate polymerizations. We outline four classes of heterogeneous photocatalysts in detail: Nanoparticles, conjugated and non‐conjugated polymer networks, metal‐organic frameworks (MOFs), and functionalized solid supports. 

This contribution discusses the control over polymerizations using a heterogeneous photocatalyst based on fluorescein polymer brushes tethered to micron-scale glass supports (FPB@SiO 2 ). FPB@SiO 2 -catalyzed photoinduced electron/energy transfer-reversible addition–fragmentation chain transfer (PET-RAFT) polymerization is shown to provide high conversions, controlled molecular weights and narrow molecular weight distributions for a variety of monomers. Moreover, the beads can catalyze PET-RAFT on gram scales, in the presence of oxygen, while allowing full catalyst recovery through simple filtration. Finally, their high shelf-life allows for multiple polymerizations and user-friendly access to precision macromolecules under mild reaction conditions even after prolonged (months) storage time. 

Abstract While organic photocatalysts provide increasingly versatile chemical pathways under mild conditions, their long‐term stability remains understudied. Here, the photobleaching behavior of xanthene dye photocatalysts is investigated. Rose Bengal, Eosin Y, and fluorescein are studied when in solution, when grafted to glass beads, and when incorporated into polymer brushes that are tethered to glass beads. This provides a comparison between xanthene's stability as a homogeneous and as a heterogeneous photocatalyst. Photobleaching is investigated using UV–vis, diffuse reflectance UV–vis (DR UV–vis), and fluorescence microscopy. Xanthene dyes as homogeneous photocatalysts exhibit the highest photostability, while the grafted systems appeared to fade more rapidly. Notably, heterogenization appears to have different effects based on the photocatalyst system, and further altering the photocatalyst environment with reagents may improve stability.