Hexapole [9]Helicene

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Helicenes are polycyclic aromatic hydrocarbons with a helical structure, presenting unique stereochemical and photophysical properties.
• The synthesis of larger helicenes, particularly beyond the [6]helicene level, remains a significant challenge in organic chemistry.
• Previous methods for synthesizing [9]helicenes are complex and often yield limited quantities.

Purpose of the Study:

• To report the first synthesis of a hexapole [9]helicene (H9H).
• To investigate the structural, optical, and electronic properties of this novel H9H molecule.
• To explore a new synthetic strategy for constructing complex, highly distorted polycyclic aromatic systems.

Main Methods:

• Co-catalyzed [2+2+2] cyclotrimerization of a dinaphthopyrene (DNP) functionalized alkyne to form a hexaaryl benzene precursor.
• Dehydrocyclization of the precursor to yield the target hexapole [9]helicene (H9H).
• Single-crystal X-ray diffraction analysis, chiral resolution, and characterization of optical and electronic properties.

Main Results:

• Successful synthesis of the first hexapole [9]helicene (H9H) via a multi-step sequence.
• X-ray crystallography revealed highly distorted and sterically hindered structural features of both the precursor and H9H.
• Characterization provided insights into the chiral, optical, and electronic behavior of the newly synthesized H9H.

Conclusions:

• The developed synthetic route provides access to a novel class of highly complex helicene architectures.
• The unique structural features of H9H are confirmed and contribute to its distinct properties.
• This work expands the scope of accessible helicene structures and their potential applications.