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Updated: Feb 16, 2026

Determination of the Photoisomerization Quantum Yield of a Hydrazone Photoswitch
Published on: February 7, 2022
Visible-light-driven two-way photoisomerization of 1-(1-pyrenyl)-2-(2-quinolyl)ethylene in neutral and protonated
Mikhail F Budyka1, Vitalii M Li
1Institute of Problems of Chemical Physics, Russian Academy of Sciences, pr. Akademika Semenova 1, Chernogolovka, Moscow region 142432, Russian Federation. budyka@icp.ac.ru.
Abstract:
Diarylethylenes with large π-systems often lose their photochemical activity (the size effect). 1-(1-Pyrenyl)-2-(2-quinolyl)ethylene (1P2QE), despite having a large conjugated π-system of 28 electrons, undergoes two-way reversible trans-cis photoisomerization both in the neutral and protonated forms with quantum yields as high as 0.13-0.83. For the neutral 1P2QE, experimental data and quantum-chemical calculations indicate a diabatic (nonadiabatic) reaction mechanism. Due to high photoisomerization quantum yields and the long-wavelength absorption band at 340-460 nm and 390-560 nm for the neutral and protonated compounds, respectively, 1P2QE can be used as a molecular photoswitch that is sensitive to visible light.
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