Mixed-Valence BN-Doped Corannulene Trimer Radical Cations

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Mixed-valence (MV) dimers are well-studied, but organic MV trimers based on open-shell polycyclic aromatic hydrocarbons are largely unexplored.
• Understanding the structure-property relationships of novel organic radical cations is crucial for developing advanced materials.

Purpose of the Study:

• To synthesize and characterize unprecedented mixed-valence boron-nitrogen (BN)-doped corannulene radical cation trimers.
• To investigate the structural, electronic, and magnetic properties of these novel organic trimers.

Main Methods:

• Chemical oxidation for synthesis of BN-doped corannulene radical cations.
• Single-crystal X-ray diffraction for unambiguous structural determination.
• Electron paramagnetic resonance (EPR) spectroscopy and variable-temperature EPR for electronic and magnetic characterization.
• Conductivity measurements to assess material properties.

Main Results:

• Successful synthesis of two types of MV BN-doped corannulene radical cation trimers, [BN-Cor1]3··2+ and [BN-Cor2]3··2+.
• X-ray diffraction confirmed trimer structures with slipped π-stacking configurations and infinite layered self-assembly of corannulene cores.
• EPR spectroscopy detected a forbidden transition (Δms=±2), confirming two unpaired electrons and MV characteristics.
• Variable-temperature EPR and conductivity measurements revealed antiferromagnetic coupling and conductivity properties in the BN-doped π-trimers.

Conclusions:

• The study presents the first purely organic mixed-valence trimers based on BN-doped corannulene radical cations.
• These trimers possess unique slipped π-stacking and layered self-assembly, indicating potential as building blocks for molecular conductors.
• The observed antiferromagnetic coupling and conductivity highlight the promising electronic and magnetic properties of these novel organic materials.