Parallel and flow photoredox chemistry enabled by advanced temperature-controlled photoreactors

Despite remarkable advancements in recent years, photoredox catalysis still faces reproducibility and scalability issues, hindering its widespread adoption in academic and industrial research. In this work, we address some of these challenges by introducing temperature-controlled modular photoreactors suitable for micro- and millimolar-scale syntheses in batch and flow. These photoreactors demonstrate a remarkable ability to precisely control internal temperature of irradiated reaction mixtures in the range from -20 °C up to +80 °C. The use of the same cooling concept and the light source ensures not only remarkable reproducibility across all positions in the batch photoreactors but also enables a seamless transfer of reaction conditions from the microscale 96-positions photoreactor (96xPR) to the flow photoreactors. By using the 96xPR, we successfully conducted screening campaigns for photoredox C‒C and C‒N couplings on a scale as little as 2 µmol. We are confident that the technological advancements detailed in this work, which we freely provide for replication, will expedite the development of photoredox chemistry in both academic and industrial settings.