The use of solar energy to power chemical reactions is a long-standing dream of the chemical community. Recently, visible-light-mediated photoredox catalysis has been recognized as the ideal catalytic transformation to convert solar energy into chemical bonds. However, scaling photochemical transformations has been extremely challenging due to Bouguer–Lambert–Beer law. Recently, we have pioneered the development of luminescent solar concentrator photomicroreactors (LSC-PMs), which display an excellent energy efficiency. These devices harvest solar energy, convert the broad solar energy spectrum to a narrow-wavelength region, and subsequently waveguide the re-emitted photons to the reaction channels. Herein, we report on the scalability of such LSC-PMs via a numbering-up strategy. Paramount in our work was the use of molds that were fabricated via 3D printing. This allowed us to rapidly produce many different prototypes and to optimize experimentally key design aspects in a time-efficient fashion. Reactors up to 32 parallel channels have been fabricated that display an excellent flow distribution using a bifurcated flow distributor (standard deviations below 10%). This excellent flow distribution was crucial to scale up a model reaction efficiently, displaying yields comparable to those obtained in a single-channel device. We also found that interchannel spacing is an important and unique design parameter for numbered-up LSC-PMs, which influences greatly the photon flux experienced within the reaction channels.

No abstract

Herein, we report the first fully automated continuous‐flow platform for fluorescence quenching studies and Stern–Volmer analysis. All the components of the platform were automated and controlled by a self‐written Python script. A user‐friendly software allows even inexperienced operators to perform automated screening of novel quenchers or Stern–Volmer analysis, thus accelerating and facilitating both reaction discovery and mechanistic studies. The operational simplicity of our system affords a time and labor reduction over batch methods while increasing the accuracy and reproducibility of the data produced. Finally, the applicability of our platform is elucidated through relevant case studies.

We report a visible light-induced trifluoromethylation and perfluoroalkylation for cysteine conjugation using Ru(bpy)3(2+) as photocatalyst and inexpensive RFI as coupling partner. The protocol allows the introduction of a variety of perfluoro alkyl groups (C1-C10) and a CF2COOEt moiety. The reaction is high yielding (56-94% yield) and fast (2 h in batch, 12 examples). Process intensification in a photomicroreactor accelerated the reaction (5 min reaction time) and increased the yields (8 examples). Quantum yield investigations support a radical chain mechanism.

Photocatalytic radical trifluoromethylation strategies have impacted the synthesis of trifluoromethyl-containing molecules. However, mechanistic aspects concerning such transformations remain poorly understood. Here, we describe in detail the mechanism of the visible-light photocatalytic trifluoromethylation of N-methylpyrrole with gaseous CF3 I in flow. The use of continuous-flow microreactor technology allowed for the determination of different important parameters with high precision (e.g., photon flux, quantum yield, reaction rate constants) and for the handling of CF3 I in a convenient manner. Our data indicates that the reaction occurs through a reductive quenching mechanism and that there is no radical chain process present.