Development of a Tunable Photoreactor for High-Throughput Experimentation

Abstract Photochemistry has revolutionized modern chemical synthesis, offering new modes of bond activation and construction under mild conditions. Yet, the systematic study of light as a tunable reaction variable remains underdeveloped, as commercial high-throughput experimentation (HTE) platforms lack the flexibility to independently tune light parameters. These constraints hinder the discovery, optimization, and understanding of light-dependent reactivity, which is critical for identifying novel photocatalysts and transformations. To meet this need in photochemistry, we disclose the development of a tunable 24-well photoreactor that enables independent control of wavelength, light intensity, and irradiation time per well to efficiently screen light-driven reactions. Herein we showcase benchmarking studies with Fe, Ce, and Cu visible light-induced homolysis (VLIH) chemistry, demonstrating that the photoreactor can facilitate excellent reproducibility across wells, attain comparable yields to commercial Kessil lamps or CFLs, and enable parallel time course studies at different wavelengths and intensities. To showcase the significance of exploring light parameters in HTE, the tunable platform was leveraged to identify multivariable correlations when selecting ideal catalyst conditions. The decarboxylative coupling between gemfibrozil and benzyl acrylate to access a quaternary center was examined with FeCl3 and various ligands under UV (λmax = 395 nm), blue (λmax = 454 nm), and broad-spectrum white light. This study revealed wavelength- and catalyst-dependent reactivity patterns, whereby the use of different ligands required varied wavelengths for optimal yields, underscoring the importance of using multidimensional light screening for reaction discovery.