Photochemistry and Transmission Pump–Probe Spectroscopy of 2‑Azidobiphenyls in Aqueous Nanocrystalline Suspensions: Simplified Kinetics in Crystalline Solids

• Published in: The journal of physical chemistry letters Vol. 8; no. 8; pp. 1845 - 1850
• Main Authors: Chung, Tim S, Ayitou, Anoklase J.-L, Park, Jin H, Breslin, Vanessa M, Garcia-Garibay, Miguel A
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 20.04.2017
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.7b00499

Aqueous nanocrystalline suspensions provide a simple and efficient medium for performing transmission spectroscopy measurements in the solid state. In this Letter we describe the use of laser flash photolysis methods to analyze the photochemistry of 2-azidobiphenyl and several aryl-substituted derivatives. We show that all the crystalline compounds analyzed in this study transform quantitatively into carbazole products via a crystal-to-crystal reconstructive phase transition. While the initial steps of the reaction cannot be followed within the time resolution of our instrument (ca. 8 ns), we detected the primary isocarbazole photoproducts and analyzed the kinetics of their formal 1,5-H shift reactions, which take place in time scales that range from a few nanoseconds to several microseconds. It is worth noting that the high reaction selectivity observed in the crystalline state translates into a clean and simple kinetic process compared to that in solution.