Functionalization of Pentacene: A Facile and Versatile Approach to Contorted Polycyclic Aromatic Hydrocarbons

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Polycyclic Aromatic Hydrocarbons (PAHs) are crucial in organic electronics.
• Developing novel PAHs with unique structures and properties remains a challenge.
• Pentacene derivatives offer a promising platform for constructing complex PAHs.

Purpose of the Study:

• To establish a facile and versatile synthesis strategy for contorted polycyclic aromatic hydrocarbons (PAHs).
• To explore the structural, photophysical, and electrochemical properties of newly synthesized PAHs.
• To investigate the potential of these contorted PAHs as organic laser dyes.

Main Methods:

• Synthesis of functionalized pentacene aldehydes.
• Intramolecular reductive Friedel-Crafts cyclization for PAH formation.
• Characterization using single-crystal X-ray diffraction, photophysical, and electrochemical studies.
• Optical resolution and characterization of enantiomers using chiral-phase HPLC, circular dichroism, and circularly polarized luminescence spectroscopy.
• Fabrication and testing of a microlaser device.

Main Results:

• A series of novel contorted PAHs (1-4) with helical chirality were successfully synthesized.
• The synthesized PAHs exhibited moderate-to-good fluorescence quantum yields.
• Optical resolution of a specific PAH (2) was achieved, and its enantiomers were characterized.
• A bottle microlaser based on PAH 3a demonstrated efficient lasing at 567.8 nm with a low threshold (0.3 mJ/cm²).

Conclusions:

• The study presents a versatile strategy for creating complex, contorted PAHs from pentacene.
• The synthesized contorted PAHs possess unique structural and optical properties, including helical chirality.
• These novel materials show significant potential for applications in organic electronics, particularly as high-quality organic laser dyes.