Direct Edge Functionalization of Corannulene-Coronene Hybrid Nanographenes

Area of Science:

• Organic Chemistry
• Materials Science
• Nanotechnology

Background:

• Electrophilic aromatic substitution is crucial for organic synthesis.
• Large nanographenes often yield complex mixtures due to lack of selectivity.
• Selective functionalization of nanographenes remains a challenge.

Purpose of the Study:

• To demonstrate regioselective edge functionalization of a curved C48 nanographene.
• To enable modular synthesis of complex nanostructures.
• To explore the optical properties of the resulting functionalized nanographenes.

Main Methods:

• Synthesis of a corannulene-coronene hybrid nanographene (C48).
• Direct, regioselective edge functionalization via bromination, nitration, formylation, and Friedel-Crafts acylation.
• Post-synthetic modifications using Suzuki-Miyaura, Sonogashira-Hagihara, and Buchwald-Hartwig amination reactions.

Main Results:

• Achieved direct and regioselective edge functionalization of the C48 nanographene in good yields.
• Demonstrated sequential substitutions to create heterofunctional structures.
• Obtained nanostructures with strong visible and near-infrared fluorescence (475-900 nm) and large Stokes shifts (>300 nm).

Conclusions:

• The edge-functionalization strategy provides modular access to complex nanostructures.
• The C48 nanographene offers a pathway to advanced materials with desirable optical properties.
• This approach achieves high functionality with a minimal carbon footprint.