Utilizing Selective Chlorination to Synthesize New Triangulenium Dyes

Jesper Dahl Jensen, Niels Bisballe, Laura Kacenauskaite, Maria Storm Thomsen, Junsheng Chen, Ole Hammerich, Bo W. Laursen*

*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

6 Citationer (Scopus)
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Abstract

Functionalization of new sites on the triangulenium structure has been achieved by early-stage chlorination with N-chlorosuccinimide (NCS), giving rise to two new triangulenium dyes (1 and 3). By introducing the chlorine functionalities in the acridinium precursor, positions complementary to those previously obtained by electrophilic aromatic substitution on the final dyes are accessed. The chlorination is selective, giving only one regioisomer for both mono- and dichlorination products. For the monochlorinated acridinium compound, a highly selective ring-closing reaction was discovered, generating a single regioisomer of the cationic [4]helicene product. Further investigations into the mechanism of the [4]helicene formation lead to the first isolation of the previously proposed intermediate of the two-step SNAr reaction, key to all aza-bridged triangulenium and helicenium systems. Late-stage functionalization of DAOTA+ with NCS gave rise to a different dichlorinated compound (2). The fully ring closed chlorinated triangulenium dyes 1, 2, and 3 show a redshift in absorption and emission, while maintaining relatively high fluorescence quantum yields of 36%, 26%, and 41% and long fluorescence lifetimes of 15, 12.5, and 16 ns, respectively. Cyclic voltammetry shows that chlorination of the triangulenium dyes significantly lowers reduction potentials and thus allows for efficient tuning of redox and photoredox properties.

OriginalsprogEngelsk
TidsskriftJournal of Organic Chemistry
Vol/bind86
Udgave nummer23
Sider (fra-til)17002–17010
Antal sider9
ISSN0022-3263
DOI
StatusUdgivet - 2021

Bibliografisk note

Funding Information:
The work was supported by the Danish Council of Independent Research (DFF-6111-00483).

Publisher Copyright:
© 2021 American Chemical Society.

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