Scalable Solvent-Free Synthesis of a Linear Heteroaromatic Trimer with Crystallization-Induced Phosphorescence

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Synthesis

Background:

• The thermal condensation of benzoguanamine (BG) and its oligomer intermediates are not well understood.
• Selective synthesis of specific oligomers, like the trimer (BG)3, is challenging.

Purpose of the Study:

• To elucidate the polymerization mechanism of benzoguanamine.
• To develop a novel strategy for the selective synthesis of the benzoguanamine trimer (BG)3.
• To characterize the structure and photophysical properties of (BG)3.

Main Methods:

• A mixed thermal condensation strategy using BG and a pre-synthesized dimer.
• Comprehensive characterization techniques (e.g., spectroscopy, crystallography) to confirm structure and properties.

Main Results:

• Successfully synthesized the benzoguanamine trimer (BG)3 with significantly enhanced yield.
• Confirmed a linear molecular structure for (BG)3.
• Observed a high molar absorption coefficient for (BG)3, double that of the dimer and four times that of the monomer.
• Demonstrated crystallization-induced phosphorescence (CIP) in crystalline (BG)3 at room temperature with a lifetime of 514.9 μs.

Conclusions:

• The novel mixed thermal condensation strategy enables selective and high-yield synthesis of (BG)3.
• (BG)3 possesses unique photophysical properties, including strong light absorption and room-temperature phosphorescence.
• This work provides insights into benzoguanamine polymerization and highlights the potential of (BG)3 in materials applications.