In situ observation of a stepwise [2 + 2] photocycloaddition process using fluorescence spectroscopy

• Published in: Nature communications Vol. 14; no. 1; p. 7766
• Main Authors: Wang, Meng-Fan, Deng, Yun-Hu, Hong, Yu-Xuan, Gu, Jia-Hui, Cao, Yong-Yong, Liu, Qi, Braunstein, Pierre, Lang, Jian-Ping
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 27.11.2023; Nature Publishing Group UK; Nature Portfolio
• Subjects: Blue shift; Coordination polymers; Crystals; Evolution; Fluorescence; Fluorescence spectroscopy; Inhomogeneity; Intermediates; Irradiation; Light irradiation; Luminous intensity; Polymers; Reaction mechanisms; Single crystals; Solid state; Spectroscopy; Spectrum analysis; Ultraviolet radiation
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-42604-9

Abstract Using highly sensitive and selective in situ techniques to investigate the dynamics of intermediates formation is key to better understand reaction mechanisms. However, investigating the early stages of solid-state reactions/transformations is still challenging. Here we introduce in situ fluorescence spectroscopy to observe the evolution of intermediates during a two-step [2 + 2] photocycloaddition process in a coordination polymer platform. The structural changes and kinetics of each step under ultraviolet light irradiation versus time are accompanied by the gradual increase-decrease of intensity and blue-shift of the fluorescence spectra from the crystals. Monitoring the fluorescence behavior using a laser scanning confocal microscope can directly visualize the inhomogeneity of the photocycloaddition reaction in a single crystal. Theoretical calculations allow us to rationalize the fluorescence behavior of these compounds. We provide a convenient strategy for visualizing the solid-state photocycloaddition dynamics using fluorescence spectroscopy and open an avenue for kinetic studies of a variety of fast reactions.