Revisiting Kekulene: Synthesis and Single-Molecule Imaging.

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Kekulene, an emblematic cycloarene, was first synthesized decades ago, with no subsequent reports until now.
• Understanding the structure and properties of complex polycyclic aromatic hydrocarbons is crucial in materials science.

Purpose of the Study:

• To achieve a new synthesis of kekulene.
• To investigate the molecular structure and bonding of kekulene using advanced techniques.

Main Methods:

• Improved synthetic route involving a double Diels-Alder reaction.
• Ultra-high-resolution Atomic Force Microscopy (AFM) imaging.
• Computational chemistry calculations.

Main Results:

• Successful re-synthesis of kekulene via an improved pathway.
• AFM imaging revealed detailed single-molecule structures.
• Computational analysis supported significant bond localization, aligning with the Clar model.

Conclusions:

• The improved synthesis provides a viable route to kekulene.
• Experimental and computational data confirm kekulene's structure with localized bonds.
• This work advances the understanding of cycloarene chemistry and molecular structure.