Chemists at the University of Basel have successfully synthesized helicenes, a group of substances used in organic light-emitting diodes (OLEDs) with a three-dimensional structure that allows them to emit circularly polarized light. This breakthrough marks a significant step forward in producing more efficient OLEDs, which are cheaper than traditional LEDs but have so far lagged in light output and lifespan. Helicenes are benzene rings joined in a helical structure and are crucial to developing OLEDs. It has been challenging to control the direction in which the molecules twist or their chirality.

The researchers created the helicenes using a C-H activation reaction, which splits a carbon-hydrogen and carbon-bromine bond and creates a carbon-carbon bond. The method allows chemists to create helicenes with the desired chirality and is suitable for longer chains of benzene rings. Researchers at Université Paris-Saclay in France confirmed that the products synthesized by the Basel team strongly absorb and emit circularly polarized light, an essential characteristic for developing new materials that rely on twisted molecules, such as OLEDs.

According to Prof. Olivier Baudoin, who led the team, the results show the great potential of this synthesis strategy for creating complex functional molecules. The team intends to synthesize more complex helicenes with improved characteristics in their next step. This new concept in synthesizing these molecules has paved the way for new and better light sources in various devices, including smartphones, tablets, and monitors. It could have significant implications for the lighting industry as a whole.

LEDs have become ubiquitous in our daily lives, but OLEDs have not yet achieved the same level of popularity. With this breakthrough in the synthesis of helicenes, developing more efficient OLEDs may become a reality. The research shows that the future of lighting may lie in twisted molecules, and the team’s synthesis method could potentially significantly impact the industry.

The novel research has been published in Nature Chemistry.

References

• Guo, S.-M., Huh, S., Coehlo, M., Shen, L., Pieters, G., & Baudoin, O. (2023). A C–H activation-based enantioselective synthesis of lower carbo[n]helicenes. Nature Chemistry. https://doi.org/10.1038/s41557-023-01174-5
• Jacobs, A. (2023, April 12). Luminous Molecules. University of Basel; University of Basel. https://www.unibas.ch/en/News-Events/News/Uni-Research/Luminous-Molecules.html