Merging a Negatively Curved Nanographene and a Carbon Nanoring

Area of Science:

• Organic Chemistry
• Materials Science
• Nanotechnology

Background:

• Molecular nanocarbons are advanced carbon materials with unique electronic and structural properties.
• Carbon schwarzites are a class of carbon allotropes with potential applications in catalysis and gas storage.
• Bottom-up synthesis offers precise control over the structure and properties of novel carbon materials.

Purpose of the Study:

• To synthesize two constitutional isomers of molecular nanocarbons by combining nanographene and carbon nanorings.
• To explore the synthesis of complex carbon structures using a bottom-up approach.
• To investigate the structural characteristics and potential for further development towards carbon schwarzites.

Main Methods:

• Attachment of C-shaped paraphenylene precursors to 2,11,18,27-tetrabromooctabenzo[8]-circulene.
• Intramolecular Yamamoto coupling reactions to form the nanocarbon framework.
• Reductive aromatization reactions to achieve the final molecular nanocarbons.
• X-ray crystallography and chiral High-Performance Liquid Chromatography (HPLC) for structural characterization.

Main Results:

• Successful synthesis of two constitutional isomers (D2 and C2v symmetry) of molecular nanocarbons.
• The D2 isomer adopted a figure-eight shape, confirmed by X-ray crystallography.
• The D2 isomer was resolved into its enantiomers using chiral HPLC.
• The C2v isomer represents a significant step towards the precision synthesis of carbon schwarzites.

Conclusions:

• The flexible octabenzo[8]-circulene scaffold allows for controlled synthesis of different isomers.
• This study demonstrates a viable bottom-up strategy for constructing complex molecular nanocarbons.
• The synthesized C2v isomer is a promising precursor for developing novel carbon schwarzites.