Recently, Wang Xiaoye's team from the College of Chemistry, Nankai University has made important progress in the field of chiral organic optoelectronic materials. A new BN-embedded double helicene molecules of excellent chiral optical properties have been developed, with absorption asymmetry factor in the visible region up to 0.033, creating a new record of asymmetry factor for helicene molecules in the visible region. The research results were published in the Journal of the American Chemical Society (JACS), an international top chemical journal. Researcher Wang Xiaoye is the only corresponding author of this paper, and doctoral student Li Jikun is the first author of this paper.
In recent years, organic circularly polarized light luminescent devices and detectors have come under the scientists' spotlights due to the potential applications of circularly polarized light in 3D display, information processing, quantum communication, disease diagnosis and other fields. In these devices, chiral organic optoelectronic materials are the core and basis, and one of the most important indicators to evaluate the performance of these materials is the asymmetry factor, which represents the capacity of material to distinguish left-handed and right-handed circularly polarized light. In the field of chiral organic optoelectronic materials, helicene, as a kind of polycyclic aromatic hydrocarbons with unique helical chiral properties fused by aromatic ring at the ortho position, has attracted considerable concern due to its high asymmetry factors. It is a key problem and challenge for the development of chiral organic photoelectric materials that how to develop novel helicene molecules with high asymmetry factors in the visible region.
A new BN-embedded bis-helicene molecule and its excellent chiral optical property
To solve the above problems, Wang Xiaoye's team has designed and synthesized a new BN-embedded bis-helicene  molecule. On the one hand, thanks to the intramolecular push-pull electronic effect brought by boron-nitrogen atom, the absorption spectrum of helicene molecular skeleton extends to the red light area. What's more, with the further red shift for the introduction of electron-donating group outside the skeleton, such helicene molecular shows strong chiral optical response in the ultraviolet-visible region (300-700 nm); On the other hand, the orbital separation due to multiple resonance effect caused by non-bonding boron and nitrogen atoms, and x-type dual helicene configuration contribute to improving the absorption asymmetry factor (GABS) of helicene molecules, resulting in a maximum GABS of helicene molecules up to 0.033 at 502 nm, which is the maximum GABS of the known helicene molecules in the visible region. In addition, the BN-embedded bis-helicene  molecule shows a spectrally tunable circular polarization luminescence (CPL) property in the red-near-infrared region and a quantum photoluminescence efficiency of up to 100%, with circularly polarized luminescence (BCPL) up to 40 M-1 cm-1. It’s a circularly polarized luminescent material with excellent property in the red-near-infrared region. These results indicate that the BN-embedded bis-helicene molecules have excellent chiral optical properties, which will provide new opportunities and new ideas for the development of chiral optoelectronic materials and devices in the future.
Link to the paper: https://pubs.acs.org/doi/10.1021/jacs.1c09058
(Reported by Jiao Jian, edited and translated by Nankai News Team.)