UV-light crosslinked photocatalytic polymer gels for batch and continuous flow reactions

Abstract

Using visible light to drive reactions is a growing field due to its potential to provide efficient pathways towards chemical syntheses. In contrast to adding photocatalysts to the reaction mixtures as small molecules, heterogeneous photocatalytic approaches provide the ability to facilitate recovery and reuse after a reaction. Herein, we describe a heterogeneous polymer gel-based photocatalyst comprised of a crosslinked terpolymer. We use an activated ester approach to substitute in an amine-functionalized Eosin Y dye while also providing benzophenone-based moieties which afford for UV-crosslinking via C,H-insertion chemistry. The resulting Eosin Y-gels were analyzed for their ability to oxidize thioanisole and their longevity in subsequent recycles for this reaction was analyzed at various light intensities. We interrogated how the incorporation of additional crosslinkers influences photocatalytic properties. Finally, the utility of Eosin Y-gels in continuous packed bed flow photoreactors was investigated, showing good long-term stability against photobleaching and high yields for extended reaction times.