Iterative Synthesis of Pyrene-Coronene Molecular Graphene Nanoribbons

Area of Science:

• Materials Science
• Organic Chemistry
• Nanotechnology

Background:

• Precise synthesis of molecular graphene nanoribbons (GNRs) is crucial for understanding structure-property relationships and enabling applications.
• Current methods for undoped GNRs face challenges in realizing diverse edge topologies and achieving significant lengths.
• Iterative synthetic strategies for undoped GNRs are underdeveloped, with a reliance on noniterative approaches.

Purpose of the Study:

• To report the iterative synthesis of a new family of undoped molecular GNRs.
• To introduce a novel edge topology and achieve unprecedented lengths in GNRs.
• To develop an effective two-step iterative synthesis for molecular GNRs.

Main Methods:

• Utilized a borylation/Suzuki/cyclodehydrogenation reaction sequence.
• Merged Suzuki coupling and cyclodehydrogenation into a single transformation step.
• Developed an effective two-step iteration sequence for GNR synthesis.

Main Results:

• Successfully synthesized a new family of undoped molecular GNRs with a novel edge topology and unprecedented length.
• Achieved strong absorption and high fluorescence efficiency in the pyrene-coronene GNRs.
• Reported molar absorptivity and fluorescence brightness values around 10^5 M^-1 cm^-1.
• Determined an intrinsic charge carrier mobility of 475 ± 32 cm^2 V^-1 s^-1.

Conclusions:

• The developed iterative method overcomes limitations in synthesizing long, undoped molecular GNRs.
• The novel GNRs exhibit excellent optical and electronic properties, paving the way for advanced applications.
• This work establishes a robust synthetic route for precisely engineered graphene nanoribbons.