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

The polymerization mechanism and the identification of key oligomer intermediates during the thermal condensation of benzoguanamine (BG) remain unclear. Herein, we report a novel mixed thermal condensation strategy using BG and a pre-synthesized dimer to selectively synthesize the trimer (BG)₃ with a significantly enhanced yield. Comprehensive characterization techniques confirm the formation of a linear molecular structure for (BG)₃. Notably, (BG)₃ exhibits a high molar absorption coefficient, approximately double the dimer and 4-fold greater than the monomer. Notably, (BG)₃ demonstrates crystallization-induced phosphorescence (CIP) with a lifetime of 514.9 μs in the crystalline state at room temperature.