Development of a Tunable Photoreactor for High-Throughput Experimentation

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 HTE plates lack the flexibility to independently tune light parameters across parallel reactions. These constraints hinder the discovery and optimization of light-dependent reactivity, which is critical for identifying new photocatalysts and novel reactivity. The control of light in high-throughput screening is particularly challenging yet it is essential for visible light-induced homolysis (VLIH) chemistry, whereby the photocatalyst is generated in situ and the optimal wavelength of irradiation may not be reported. Herein, 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. In benchmarking studies of Fe VLIH chemistry, the tunable platform demonstrated excellent reproducibility across wells (standard deviation: 3% yield), providing reliable comparison of parallel reaction outcomes. Moreover, the yield obtained in each well was comparable to the commercially available single-wavelength platforms. The plate successfully maintained room temperature even after a day of continuous irradiation and no significant light penetration was observed between wells. Additionally, the versatility of the photoreactor was demonstrated by screening a range of VLIH-mediated transformations, employing Fe, Ce, and Cu salts, each requiring distinct irradiation wavelength and time within the same plate. These results underscore the utility of this platform in efficiently screening photochemical reactions, where incorporation of wavelength as a tunable variable provides the opportunity to expand the dimensions of screening and high-throughput reaction discovery.