ArticleCommunications chemistry2024
A cautionary tale of basic azo photoswitching in dichloromethane finally explained.
Article in Communications chemistry, 2024. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
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Who cites it
4 citing papers in PubMed.
- Greener Solvents for the Photoisomerization and Catalytic Heat Release of a Norbornadiene-Based Molecular Solar Thermal Energy Storage System.Advanced science (Weinheim, Baden-Wurttemberg, Germany) · 2026Article
- Real-Time Vibrational Spectroscopy Reveals an Inversion Transition State in the Photoisomerization of Phenylazoimidazole.The journal of physical chemistry letters · 2026Article
- On the unexpected mechanism of isomerization in tautomerizable azo photoswitches.Communications chemistry · 2026Article
- Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications.Beilstein journal of organic chemistry · 2025Review
Corrections and comments
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Authors and funding
5 authors.
Funding
Abstract
Many studies of azobenzene photoswitches are carried out in polar aprotic solvents as a first principles characterization of thermal isomerization. Among the most convenient polar aprotic solvents are chlorinated hydrocarbons, such as DCM. However, studies of azobenzene thermal isomerization in such solvents have led to spurious, inconclusive, and irreproducible results, even when scrupulously cleaned and dried, a phenomenon not well understood. We present the results of a comprehensive investigation into the root cause of this problem. We explain how irradiation of an azopyridine photoswitch with UV in DCM acts not just as a trigger for photoisomerization, but protonation of the pyridine moiety through photodecomposition of the solvent. Protonation markedly accelerates the thermal isomerization rate, and DFT calculations demonstrate that the singlet-triplet rotation mechanism assumed for many azo photoswitches is surprisingly abolished. This study implies exploitative advantages of photolytically-generated protons and finally explains the warning against using chlorinated solvent with UV irradiation in isomerization experiments.
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Registered trials
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