Heterocyclic [9]Helicenes Exhibiting Bright Circularly Polarized Luminescence

Area of Science:

• Organic Chemistry
• Materials Science
• Spectroscopy

Background:

• Helicenes are chiral aromatic hydrocarbons with unique photophysical properties.
• Developing efficient synthetic routes and understanding their chiroptical behavior is crucial for advanced applications.

Purpose of the Study:

• To establish a concise synthetic strategy for heterocyclic [9]helicenes.
• To develop a preparative-scale protocol for enantiomeric resolution.
• To characterize the photophysical and chiroptical properties of these novel helicenes.

Main Methods:

• Concise synthesis of heterocyclic [9]helicenes.
• Preparative-scale optical resolution of enantiomers.
• Characterization using single-crystal X-ray diffraction, spectroscopy, and computational methods.

Main Results:

• Achieved high fluorescence quantum yield (up to 65%).
• Observed large dissymmetry factors in chiroptical properties.
• Demonstrated record circularly polarized luminescence (CPL) brightness (17,000 M⁻¹ cm⁻¹) for heterocyclic helicenes.
• Correlated experimental CPL with quantum chemical calculations.

Conclusions:

• The developed synthetic strategy is effective for preparing enantiomerically pure heterocyclic [9]helicenes.
• The study provides a high CPL brightness benchmark for this class of compounds.
• Quantum chemical calculations can accurately predict chiroptical properties, aiding future molecular design.