Dipole–Dipole Interactions for Reducing Sensitivity: Synthesis and Characterization of Thermally Stable, Fluorescent Energetic Materials Based on Benzopyridotetraazapentalene

To meet the requirements of extreme environments, desensitivity, and the development of high-temperature-resistant energetic materials are urgently needed. Herein, two high-temperature-resistant fluorescent energetic materials, 9,10-dichloro-2,4,8-trinitrobenzo[4′,5′][1,2,3]triazolo[2′,1′:2,3][1,2,3]triazolo[4,5-b]pyridin-6-ium-5-ide (5a) and 3,9,10-trichloro-2,4,8-trinitrobenzo[4′,5′][1,2,3]triazolo[2′,1′:2,3][1,2,3]triazolo[4,5-b]pyridin-6-ium-5-ide (5b), were synthesized. The thermal decomposition temperatures were determined to be 339 °C for 5a and 272 °C for 5b. Both meet the requirements for heat-resistant explosive materials. By the BAM method test, 5b (IS = 20 J, FS > 360 N) displayed similar friction sensitivity (FS) but better impact sensitivity (IS) than 5a (IS = 18 J, FS > 360 N). The optimized geometries and electrostatic potential (ESP) surface analysis proved the dipole–dipole interactions of Cl with the O atoms in adjacent –NO2 groups in 5b, and from the perspective of compound structures, the main reason for the better impact sensitivity of 5b may be due to Cl···O dipole–dipole interactions. Besides, 5a exhibited an emission peak at 551 nm, 5b displayed a red-shift emission peak at 562 nm, manifesting their potential in the use of energetic compound detection. This work could offer guidelines for designing and synthesizing new insensitive heat-resistant fluorescent energetic materials and evidence the effectiveness of dipole–dipole interactions in reducing sensitivity of energetic explosives.