Triindenoolympicenyl Radical with High Reduction Potential

Area of Science:

• Organic Chemistry
• Materials Science
• Electrochemistry

Background:

• Spin-1/2 open-shell polycyclic aromatic hydrocarbons (PAHs) display significant redox amphotericity.
• Achieving high reduction potentials (>-0.5 V) in PAHs is synthetically challenging.
• Tuning redox properties is crucial for developing advanced organic electronic materials.

Purpose of the Study:

• To synthesize and characterize a novel stable open-shell polycyclic aromatic hydrocarbon radical.
• To investigate the effect of indeno annulation on the redox properties of olympicenyl radicals.
• To establish a new strategy for enhancing the reduction potentials of PAHs.

Main Methods:

• Synthesis and crystalline-state isolation of triindenoolympicenyl radical (TIOR).
• Density Functional Theory (DFT) calculations to predict electronic structure and redox potentials.
• Electrochemical analyses (e.g., cyclic voltammetry) to determine reduction potentials.

Main Results:

• A stable triindenoolympicenyl radical (TIOR) was successfully synthesized and isolated.
• Indeno annulation shifted the first reduction potential of TIOR by approximately 1.0 V to more positive values.
• Compared to the triisopropylsilylethynyl (TIPSE)-substituted olympicenyl radical (OR1), TIOR exhibits significantly enhanced reduction potential.

Conclusions:

• Indeno annulation is an effective strategy for fine-tuning the redox behavior of open-shell PAHs.
• The synthesized TIOR demonstrates potential for applications requiring high reduction potentials.
• This work provides a pathway for designing novel organic materials with tailored electrochemical properties.