A pyridine-fused triazapentalene shows weak fluorescence in solution and is readily accessible via nitrene-mediated cyclization. In this study, a modified Cadogan reaction was used to synthesize HetATAP 1. Palladium-catalyzed reactions have been used as post-functionalization methods. Interestingly, modified Suzuki cross-couplings with various boronic acids resulted in poor to moderate yields of HetATAPs 2–5 which were arylated at the azole moiety. Direct CH arylation of HetATAP 1 gave the products with the same regiochemistry in satisfactory yields. The structures of HetATAPs 2–5 were confirmed using NMR analysis. In addition, the photophysical properties of HetATAPs 1–5 were studied under various conditions. Particularly, the emission of HetATAPs 2–5 is enhanced in the solid and aggregate state.

A pyridine-fused triazapentalene shows weak fluorescence in solution, and is readily accessible via nitrene-mediated cyclization. In this research, a modified Cadogan reaction was used to synthesize HetATAP1. Palladium-catalyzed reactions have been demonstrated as post-functionalization methods. Interestingly, Suzuki cross-coupling with various boronic acids resulted in poor to moderate yields of the products HetATAP2-5 arylated on the azole moiety. Direct CH arylation of HetATAP1 gave the products with the same regiochemistry in satisfactory yields. The structures of HetATAP2-5 were confirmed using NMR analysis. In addition, the fluorescence properties of HetATAP2-5 were studied in the solid-state and solution at room temperature, and the photophysical properties of HetATAP3 and 4 in the aggregated state were both measured in ACN/water and THF/water mixtures, respectively.