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A Chiral Saddle-Shaped Nanographene With Two Heptagon-Embedded [4]Helicenes
Felix Trautner1,2, Boris Borrisov2, Philipp Royla3
1Max Planck Institute of Microstructure Physics, Halle, Germany.
Angewandte Chemie (International Ed. in English)
|June 3, 2026
Summary
Researchers developed a new method to synthesize chiral non-benzenoid nanographenes (NGs) with stable chirality and unique saddle shapes. These nanographenes exhibit strong host-guest interactions with fullerenes, paving the way for advanced materials.
Area of Science:
- Organic Chemistry
- Materials Science
- Supramolecular Chemistry
Background:
- Chiral non-benzenoid nanographenes (NGs) are attractive but difficult to synthesize due to challenges in creating non-hexagonal rings and stable chirality.
- Existing synthetic strategies often fail to achieve both non-hexagonal ring formation and inherent chirality simultaneously.
Purpose of the Study:
- To develop a novel synthetic strategy for constructing chiral saddle-shaped nanographenes (cSNGs).
- To investigate the chiroptical properties and host-guest interactions of the synthesized cSNGs.
Main Methods:
- Stepwise oxidation of an anthracene-containing oligophenylene precursor.
- Scholl-type oxidation to form sp3-defect heptagons.
- Oxidative dehydrogenation to yield the target cSNG with heptagon-embedded [4]helicenes.
- Single-crystal X-ray diffraction for structural confirmation.
- Chiral resolution and chiroptical response measurements.
- Host-guest interaction studies with fullerenes (C60 and C70).
Main Results:
- Successfully synthesized a novel chiral saddle-shaped nanographene (cSNG) incorporating two heptagon-embedded [4]helicenes.
- Structural confirmation via single-crystal analysis revealed a saddle geometry with intrinsic chirality.
- The cSNG exists as configurationally stable enantiomers, enabling chiral resolution and exhibiting enhanced chiroptical responses.
- Demonstrated strong host-guest interactions with C60 and C70 fullerenes, with high association constants.
- Crystallographic analysis of cocrystals revealed a unique 1:3 binding mode for supramolecular complexation.
Conclusions:
- The developed stepwise oxidation strategy provides a feasible route to chiral non-benzenoid nanographenes with stable chirality and unique saddle shapes.
- The synthesized cSNGs possess significant potential for applications in chiral recognition and supramolecular chemistry due to their pronounced chiroptical properties and strong fullerene binding capabilities.
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