cAAC-Stabilized 9,10-diboraanthracenes-Acenes with Open-Shell Singlet Biradical Ground States

Area of Science:

• Organic Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Larger acenes offer high charge-carrier mobility and narrow highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gaps, crucial for organic electronics.
• Acene performance scales with fused benzene rings, but bulk synthesis is limited to heptacene.
• Theoretical models predict open-shell biradical or polyradical ground states in larger acenes, yet experimental validation remains limited.

Purpose of the Study:

• To develop novel acene derivatives with reduced HOMO-LUMO gaps without increasing molecular size.
• To investigate the electronic properties and ground state characteristics of boron-substituted acenes.
• To explore the potential of these new materials in organic electronic applications.

Main Methods:

• Incorporation of two boron atoms into the anthracene skeleton.
• Stabilization of boron centers using cyclic (alkyl)(amino)carbene ligands.
• Characterization of the electronic structure and ground state properties of the resulting 9,10-diboraanthracenes.

Main Results:

• Successfully synthesized neutral 9,10-diboraanthracenes with significantly lowered HOMO-LUMO gaps.
• Demonstrated that these diboraanthracenes possess disjointed, open-shell singlet biradical ground states.
• Achieved reduced HOMO-LUMO gaps without the need for extending the conjugated π-system.

Conclusions:

• Boron incorporation offers a viable strategy to tune the electronic properties of acenes.
• The synthesized diboraanthracenes exhibit unique biradical character, confirming theoretical predictions for related systems.
• These findings open new avenues for designing high-performance organic electronic materials.