C₂-Symmetric Perylene-Embedded Double [5]Helicenes

Area of Science:

• Organic Chemistry
• Materials Science
• Photochemistry

Background:

• Chiroptical properties of polycyclic aromatic hydrocarbons (PAHs) are crucial for developing advanced circularly polarized materials.
• Enhancing quantum yields and dissymmetry factors is essential for improving material performance.

Purpose of the Study:

• To synthesize a novel [n]helicene-functionalized PAH with enhanced chiroptical properties.
• To investigate the potential of perylene-embedded double [5]helicene for circularly polarized materials.

Main Methods:

• A two-step synthesis involving Suzuki-Miyaura cross-coupling and base-catalyzed condensation.
• Separation of enantiomers using chiral High-Performance Liquid Chromatography (HPLC).
• Characterization of chiroptical properties, including quantum yield and dissymmetry factors (g_abs, g_lum).

Main Results:

• Successful synthesis of a C2-symmetric perylene-embedded double [5]helicene with a configurational stability of 23 kcal mol⁻¹.
• Separation of short-lived enantiomers was achieved.
• The synthesized compound demonstrated significantly enhanced chiroptical properties compared to pristine [5]helicene, with a quantum yield of 0.7 and g_abs up to 8.8 × 10⁻³.

Conclusions:

• The novel perylene-embedded double [5]helicene exhibits superior chiroptical performance.
• This compound holds promise for the development of advanced circularly polarized materials.
• The synthetic strategy provides a pathway for designing new helical PAHs with tailored optical properties.