LED-Illuminated NMR Spectroscopy: A Practical Tool for Mechanistic Studies of Photochemical Reactions

This Concept article highlights the development of a novel analytical tool, LED-NMR (a combination of in situ light illumination using a light-emitting diode and NMR spectroscopy) and its variant UVNMR (LED-NMR coupled with UV/Vis absorption spectroscopy), as well as their applications in the mechanistic investigation of light-induced transformations. The utility of these new tools has been demonstrated by providing rich kinetic and structural data of reaction species offering mechanistic insights into photochemical and photocatalytic reactions. Furthermore, NMR actinometry has been recently developed as a practical and simple method for quantum yield measurements. Quantum yield is an important parameter in photo-induced processes, but is rarely measured in practice because of the barriers associated with traditional actinometry. These new tools and techniques streamline measurements of the quantum efficiency while affording informative mechanistic insights into photochemical reactions. We anticipate these techniques will enable chemists to further advance the rapidly emerging photochemistry field.