A highly fluorescent bora[6]helicene exhibiting circularly polarized light emission

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Helicenes are chiral aromatic hydrocarbons with unique photophysical properties.
• Heteroatom-doped helicenes offer tunable electronic and optical characteristics.
• Configurationally stable helicenes are crucial for advanced applications.

Purpose of the Study:

• To synthesize the longest and first configurationally stable pristine borahelicene.
• To investigate the photophysical properties of the novel borahelicene.
• To explore the self-assembly and complexation behavior of helicenes.

Main Methods:

• Organic synthesis of 19c-boratribenzo[gh,jk,mn][6]helicene.
• X-ray single crystal diffraction analysis.
• Photophysical measurements including fluorescence and CPL emission.
• Complexation studies with azahelicenes.

Main Results:

• Successful synthesis of the longest pristine borahelicene (19c-boratribenzo[gh,jk,mn][6]helicene).
• Observed intense orange fluorescence and high quantum yield (up to 84%) CPL emission.
• X-ray analysis confirmed a twisted helical structure and intermolecular stacking.
• Formation of a hetero-chiral π-π-stacked helicene dimer through complexation.

Conclusions:

• The novel borahelicene is a promising candidate for chiroptical applications.
• The study expands the scope of stable, configurationally defined helicenes.
• Helicene complexation offers new pathways for designing supramolecular architectures.