Photochemical transformation of dichloromethane to chloroform: insights into the mechanism of aza[5]helicene photoprotonation

Photochemical transformation of dichloromethane to chloroform: insights into the mechanism of aza[5]helicene photoprotonation Full article

Journal

Journal of Photochemistry and Photobiology A-chemistry
ISSN: 1010-6030 , E-ISSN: 1873-2666

Output data

Year: 2026, Volume: 472, Article number : 116767, Pages count : DOI: 10.1016/j.jphotochem.2025.116767

Authors

Tamozhnikova Veronica S. ¹ , Tsentalovich Yuri P. ² , Eltsov Ilia V. ³ , Buravlev Alexander A. ^3,4 , Balakhonov Roman Yu. ⁵ , Mekeda Igor S. ⁵ , Shirinian Valerii Z. ⁵ , Wang Lei ⁶ , Glebov Evgeni M. ^1,3

Affiliations

1	V.V. Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, 3 Institutskaya Str., 630090 Novosibirsk, Russian Federation
2	International Tomography Center, Siberian Branch of the Russian Academy of Sciences, 3a Institutskaya Str., 630090 Novosibirsk, Russian Federation
3	Novosibirsk State University, 2 Pirogova Str., 630090 Novosibirsk, Russian Federation
4	N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 9 Lavrentiev Prosp., 630090 Novosibirsk, Russian Federation
5	N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Prosp., Moscow 119991, Russian Federation
6	Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 100085 Beijing, China

Aza[5]helicenes of the furoquinoline series have two important features: (a) possibility to modulate photophysical properties by protonation, and (b) they are good fluorophores that exhibit exceptional photostability in chlorine-free organic solvents. Light irradiation in chlorine-containing solvents was known to result in photoprotonation. In this work photophysics and photochemistry of a typical aza[5]helicene, namely 3-methoxy-6-(4-methoxyphenyl)naphtho[1′,2′:4,5]furo[2,3-c]quinoline (compound Hel) in dichloromethane (DCM) was studied using stationary photolysis with UV–Vis and NMR registration, time-resolved fluorescence and nanosecond laser flash photolysis. The free base aza[5]helicene was found for the first time to promote the transformation of dichloromethane to chloroform upon irradiation with UV light (308 nm). Studies of the quantitative characteristics of Hel and HelH+ (fluorescence quantum yields, spectra and kinetic properties of the triplet states –showed that photoprotonation occurs in two ways. The first pathway is started by an electron transfer from an excited Hel molecule to a solvent molecule, followed by an H atom transfer from a solvent molecule to the Helradical dot+ radical cation. The second pathway of HelH+ formation is the reaction between Hel and HCl formed at the first stage. A quantitative mechanism of photoprotonation is proposed that explains all the observed experimental data.

Tamozhnikova V.S. , Tsentalovich Y.P. , Eltsov I.V. , Buravlev A.A. , Balakhonov R.Y. , Mekeda I.S. , Shirinian V.Z. , Wang L. , Glebov E.M.
Photochemical transformation of dichloromethane to chloroform: insights into the mechanism of aza[5]helicene photoprotonation
Journal of Photochemistry and Photobiology A-chemistry. 2026. V.472. 116767 . DOI: 10.1016/j.jphotochem.2025.116767 WOS OpenAlex

Web of science:	WOS:001569448700001
OpenAlex:	W4414061953

Пока нет цитирований