Naslov
Photochemical deuteration of phenyl-substituted pyrroles and indoles in CD3CN-D2O and CH3CN-D2O

Autori
Basarić, Nikola ; Franco-Cea, Alfredo ; Alešković, Marija ; Mlinarić-Majerski, Kata ; Wan, Peter

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
XXIII IUPAC Symposium on Photochemistry : abstracts / - Ferrara, 2010, 148-148

Skup
IUPAC Symposium on Photochemistry )23 ; 2010)

Mjesto i datum
Ferrara, Italija, 11.07.2010. - 16.07.2010

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
pyrroles; indoles; photochemistry; deuteration; radical cations

Sažetak
Excited state intramolecular proton transfer (ESIPT) is a fundamental photochemical process of significant importance in biology and chemistry. The most common acidic site in ESIPT is phenolic OH whereas the basic site is pyridine or imidazole nitrogen. Furthermore, Wan et al reported a new ESIPT process taking place on 2-phenylphenol wherein in the singlet excited state the phenolic OH becomes sufficiently acidic to protonate the carbon atom of the adjacent aromatic ring which becomes more basic [1]. In addition to the proton transfer reactions wherein the phenol OH is the acidic site, ESIPT can take place from the NH of pyrrole or indole. For example, Waluk et al reported ESIPT for 2-(2’-pyridyl)pyrrole, 2-(2’-pyridyl)indole and 7-(2’-pyridyl)indole [2]. Prompted by the finding of the ESIPT in o-hydroxybiphenyls, pyridylindoles and pyridylpyrrole, and by the isotope effects in the photophysics of indoles, we investigated the possibility of a formal H-transfer from the solvent or the nitrogen atom of aza-heterocycles to a carbon atom of the adjacent phenyl ring in a series of heterocycles 1-6. Irradiation of 2, 3, and 6 in CH3CN-D2O gives rise to deuterium exchange at C-atoms of the heterocycle and the adjacent phenyl ring. Photolysis of 1, 2, 3, 4 and 6 in CD3CN-D2O also leads to deuteration at C-atoms with significantly higher yield. The reaction mechanism was investigated by performing product study, fluorescence and laser flash photolysis. The mechanism most probably involves ejection of an electron on excitation and formation of radical cations that abstract D-atoms from CD3CN or undergo bimolecular D-abstraction. The other possible mechanism of deuterium exchange may take place via a homolytic N-D cleavage and recombination of the radical pair [3].

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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