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Pyrene-Fused Azahelicene Showing Circularly Polarized Luminescence.
Chihiro Maeda1, Yukino Daigen1, Sayaka Michishita1
1Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama 700-8530, Japan.
Organic Letters
|June 13, 2025
Summary
A new bispyrene-fused azahelicene exhibits bright circularly polarized luminescence (CPL). Its NH group enables CPL modulation upon binding with fluoride anions or TBD, showing potential for sensing applications.
Area of Science:
- Organic Chemistry
- Materials Science
- Photophysics
Background:
- Azahelicenes are a class of chiral aromatic compounds with unique photophysical properties.
- Carbazole and pyrene derivatives are widely explored for their luminescence characteristics.
Purpose of the Study:
- To synthesize a novel bispyrene-fused azahelicene.
- To investigate its circularly polarized luminescence (CPL) properties.
- To explore the potential of the azahelicene as a sensor for specific anions.
Main Methods:
- Scholl reaction for synthesis of the bispyrene-fused azahelicene.
- Spectroscopic analysis to characterize the compound and its luminescence.
- Titration studies to determine binding constants with anions.
Main Results:
- Successful synthesis of 3,6-bis{2-(pyren-2-yl)phenyl}carbazole via Scholl reaction.
- Observation of bright CPL in the visible region due to cross-stacked pyrene units (interplanar distance 3.34 Å).
- Modulation of CPL to the red region upon interaction with fluoride anions (F-) and TBD, with a high binding constant (Ka = 3 × 10^5 M^-1) for F-.
Conclusions:
- The synthesized bispyrene-fused azahelicene is a promising CPL-emitting material.
- The NH moiety provides a responsive site for anion sensing, enabling CPL-based detection.
- This study highlights the potential of tailored azahelicene structures for advanced optical materials and sensors.
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