π-Extended Rubrenes via Dearomative Annulative π-Extension Reaction

Area of Science:

• Organic electronics
• Materials science
• Synthetic organic chemistry

Background:

• Rubrene is a prominent organic semiconductor known for high carrier mobility.
• Late-stage functionalization of rubrene is underdeveloped, limiting material diversity.
• Expanding the π-system of organic semiconductors can tune their electronic properties.

Purpose of the Study:

• To develop a method for late-stage π-extension of rubrene.
• To synthesize and characterize novel rubrene derivatives with extended acene cores.
• To evaluate the electronic properties and potential applications of these new materials.

Main Methods:

• Dearomative annulative π-extension (DAPEX) strategy.
• Diels-Alder reaction of rubrene with 4-methyl-1,2,4-triazoline-3,5-dione.
• Iron-catalyzed annulative diarylation, radical-mediated oxidation, and thermal cycloreversion.

Main Results:

• Successfully synthesized one-side and two-side π-extended rubrenes.
• Observed red shifts in absorption and emission spectra, indicating electronic π-system extension.
• Two-side π-extended rubrene exhibited brick-wall packing with significant π-π interactions.
• Fabricated organic field-effect transistors (OFETs) demonstrating a maximum hole mobility of 1.49 × 10^-3 cm²V^-1 s^-1.

Conclusions:

• The DAPEX method enables efficient late-stage π-extension of rubrene.
• π-extended rubrenes possess tunable electronic and optical properties.
• Two-side π-extended rubrene shows promise for applications in organic electronics due to its charge transport capabilities.