Heterocyclic [9]helicenes exhibiting bright circular polarized luminescence

We describe a concise synthetic strategy for the preparation of heterocyclic [9]helicenes and a simple preparative-scale protocol for the optical resolution of the resulting M- and P-enantiomers. The helicenes were characterized by single-crystal X-ray diffraction along with a range of spectroscopic...

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Bibliographic Details
Published in:Chemistry : a European journal 2023-07, p.e202301815
Main Authors: Warthegau, Stefan S, Hillers-Bendtsen, Andreas E, Pedersen, Stephan K, Rindom, Cecilie, Braestrup, Christoffer, Jensen, Jeppe S, Hammerich, Ole, Thomsen, Maria S, Kamounah, Fadhil S, Norman, Patrick, Mikkelsen, Kurt V, Brock-Nannestad, Theis, Pittelkow, Michael
Format: Article
Language:English
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Summary:We describe a concise synthetic strategy for the preparation of heterocyclic [9]helicenes and a simple preparative-scale protocol for the optical resolution of the resulting M- and P-enantiomers. The helicenes were characterized by single-crystal X-ray diffraction along with a range of spectroscopic and computational techniques. A fluorescence quantum yield of up to 65% was observed, and the chiroptical properties of both M- and P-helicenes revealed large dissymmetry factors. The CPL brightness reaches up to 17 M-1 cm-1, as measured experimentally and verified computationally, which makes this the highest CPL brightness among heterocyclic helicenes. We describe how chiroptical properties (both CD and CPL) can be described and predicted using DFT calculations. The synthetic approach also reveals by-products that originate from internal oxidation reactions, presumably mediated by the close proximity of the π-surfaces in the helicene structure.
ISSN:1521-3765
DOI:10.1002/chem.202301815