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Updated: Jan 21, 2026

Determination of the Photoisomerization Quantum Yield of a Hydrazone Photoswitch
Published on: February 7, 2022
ON/OFF Photostimulation of Isatin Bipyridyl Hydrazones: Photochemical and Spectral Study
Róbert Šandrik1, Pavol Tisovský2, Klaudia Csicsai1
1Faculty of Natural Sciences, Institute of Chemistry, Comenius University, Ilkovičova 6, Mlynská dolina CH-2, SK-842 15 Bratislava, Slovakia.
Abstract:
Four novel isatin hydrazones containing bipyridyl fragments were synthesized as potential ON/OFF switches. Hydrazone Z-isomers exhibit high thermal stability. The characteristic photochemical reaction for all studied hydrazones is the Z-E isomerization in CHCl3. After irradiation of hydrazones 1 and 2 in dimethylformamide (DMF), the photoreaction products are tautomers. When using light with the appropriate wavelength, the photo-tautomerization reaction is reversible. In these conditions, studied hydrazones have ON/OFF switch properties. In the case of hydrazones 1 and 2, by alternating heat and light stimulation it is possible to control the isomerization process reversibly. In the presence of fluoride ions, NH hydrogen from the studied hydrazones is cleaved, and the corresponding anions are formed. The resulting anions of Z-isomers are changed to the corresponding E-isomer at room temperature.
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