Only Two Steps to Synthesize Complex Nanographenes

August 26, 2026

Fusing diverse aromatic rings to construct planar and negatively curved structures

A joint research team composed of the RIKEN Pioneering Research Institute, the RIKEN CSRS, and Nagoya University has successfully developed a new strategy to synthesize diverse and complex nanographenes from polycyclic aromatic hydrocarbons (PAHs) in a short process.

The research team has established a new strategy called two-step annulative π-extension (two-step APEX). This approach fuses unfunctionalized PAHs to structurally diverse naphthalene skeletons via a palladium catalyst, followed by oxidative ring closure. Conventional APEX constrains the structural variety of nanographenes that can be synthesized because applicable π-extending reagents are limited. The approach in this study enables the introduction of sterically congested polyaryl motifs, leading to the successful synthesis of planar and curved nanographenes with 8 to 10 fused rings. Particularly, the researchers successfully created largely curved nanographenes with negative curvatures, containing five-, six-, and seven-membered rings. They also elucidated their three-dimensional structures, aromaticity, and absorption and emission profiles.

The findings of this study have successfully expanded the chemical space of nanographenes, a feat that was difficult to achieve using existing techniques. These nanographenes will hopefully help establish a new synthetic basis for exploring unknown functions of light and electrons derived from their structures.

 

Original article

Angewandte Chemie International Edition　DOI: 10.1002/anie.2205198

H. Katsuragawa, Y. Toyama, S. Mikawa, K. P. Kawahara, H. Ito, K. Itami,

"Diversity-Oriented Two-step Annulative π-Extension Enables Access to Structurally Complex Nanographenes".

Contact

Kenichiro Itami
Team Director
Expanded Chemical Space Research Team