Oxidative photocyclization of 4,5-diphenylimidazoles: A commentary to the paper "Invisible photochromism and on–off switch based on thiophene-imidazole fused derivatives: Synthesis, properties and applications".

[Display omitted] • Oxidative photocyclization of 4,5-diphenyl-substituted imidazoles led to 9,10-phenanthroimidazoles. • The intermediate 4a,4b-dihydrophenanthrene derivatives are very unstable species. • The revised structures of photoproducts, reported in [ J. Photochem. Photobiolog. A 2024 , 454 , 115750]. In the recent paper of S. Pu and coworkers (J. Photochem. Photobiolog. A 2024 , 454 , 115750), three novel 4,5-diphenylimidazole derivatives were studied. The fluorescent properties of these compounds changed drastically upon UV irradiation, as a result of irreversible phototransformation. As products of this reaction, the authors proposed questionable 7a,7b-dihydrophenanthro[9,10-d]imidazoles with completely non-aromatic core. Based on the literature data as well as author's results, we suggest more believable structures of photoproducts, formed via well-known oxidative photocyclization (Mallory reaction) or photocyclization / H-migration. [ABSTRACT FROM AUTHOR]