Negatively Curved Heptagon-Containing Carbon π-Scaffolds Part 2

• Applicant: Professor Dr. Frank Würthner
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 551034153

After having demonstrated the formation of a variety of heptagon-containing sp2-hybridized polycyclic aromatic hydrocarbon (PAH) frameworks by a novel borylation-mediated π-extension protocol in part 1 of this project, now in part 2 more extended pi-conjugated molecules bearing several heptagon units either in linear-helically extended structures or in a macrocyclic nanobelt are addressed. Further, making use of the negative curvature of heptagon-containing saddle-shaped PAHs, their supramolecular interaction with C60 and C70 fullerenes will be investigated by means of titration studies. Toward this goal both heptagon-containing PAHs and fullerene derivatives will be equipped with solubilizing groups. Furthermore, bis-fullerenes with their fullerene units being separated by various spacer groups and equipped with solubilizing alkyl chains will be explored. We expect that multiple PAH guest molecules will enwrap the fullerenes and bis-fullerenes, leading to supramolecular complexes of various stoichiometry that are of fundamental interest as substructures of “schwarzite” carbon allotropes. Beyond the creation of complexes of bis-fullerenes with curved PAHs in solution we also aim for co-crystals that can be characterized by single crystal X-ray crystallography. Such solid state structures may exhibit interesting (photo-)conducting properties that will be addressed in our future research. We expect this project to provide new fundamental insights into negatively curved PAHs as well as to lay a foundation for the bottom-up synthesis of schwarzite carbon allotropes.

• DFG Programme: Research Grants