Azulene-Based π-Functional Materials: Design, Synthesis, and Applications.

Area of Science:

• Organic Chemistry
• Materials Science
• Organic Electronics

Background:

• Azulene, an isomer of naphthalene, possesses unique photophysical properties and electronic structure, making it a promising building block for advanced materials.
• Previous research on azulene-based materials faced challenges in molecular design and synthesis, particularly in creating novel building blocks and utilizing its donor-acceptor structure.
• The incorporation of azulene units and the intelligent design of azulene derivatives for constructing polycyclic aromatic hydrocarbons (PAHs) and heteroaromatics remained underexplored.

Purpose of the Study:

• To summarize efforts on the design, synthesis, and applications of novel azulene-based π-functional materials.
• To explore new azulene-based building blocks for optoelectronics and conjugated polymers.
• To investigate azulene-fused heteroaromatics and azulene-capped organic conjugated molecules.

Main Methods:

• Design and synthesis of azulene-based aromatic diimides, including 2,2 -biazulene-1,1 ,3,3 -tetracarboxylic diimide (BAzDI) and its derivatives.
• Development of 2,6-azulene-based conjugated polymers and azulene-fused isoindigo analogues.
• Synthesis of azulene-based heteroaromatics (BN-heteroaromatics, azulene-pyridine-fused systems) and azulene-capped molecules.

Main Results:

• Creation of novel π-conjugated structures, including BAzDI derivatives exhibiting antiparallel stacking and azulenoisoindigo with reversible redox and proton responsiveness.
• Development of 2,6-azulene-based conjugated polymers with high organic field-effect transistor (OFET) performance and proton responsiveness.
• Synthesis of azulene-fused BN-heteroaromatics with selective fluoride ion response and azulene-pyridine-fused heteroaromatics with promising OFET performance.

Conclusions:

• Azulene is a versatile building block for designing advanced π-functional materials with unique electronic and stimuli-responsive properties.
• The developed materials, including conjugated polymers and heteroaromatics, show significant potential for applications in organic electronics and sensing.
• This work expands the scope of azulene chemistry, offering new strategies for molecular design and synthesis of functional organic materials.