A Simple Synthesis of Luminescent π-Conjugated Materials having fDTBT Derivatives

We developed a simple and rapid process for synthesizing dithieno[3',2':3,4; 2'',3'':5,6]benzo[1,2-c][1,2,5]thiadiazole (fDTBT) derivatives using crystalline sulfur and internal alkynes, wherein thiophene is cyclized to benzothiadiazole. Cyclized derivatives were synthesized in three or five steps using this reaction, whereas the conventional synthesis methods involved seven steps and hazardous reactions with explosive properties. The absorption spectra of the synthesized fDTBT derivatives in chloroform solution revealed a new absorption band owing to the cyclization. All three compounds exhibited orange-to-red luminescence, and the maximum absolute quantum yield was determined to be 67%, demonstrating excellent luminescence.