Tuning the thermal decomposition pathways and sensitivity of 1,2,3-triazole-based energetic regioisomers via external...

Regioisomerism and external electric fields (EEFs) play important roles in regulating the stability and decomposition behavior of energetic materials, yet their synergistic effects remain poorly understood. Herein, density functional theory was employed to investigate two triazole-based energetic regioisomers, 4-nitro-1-(1H-tetrazol-5-yl)-1H-1,2,3-triazol-5-amine (C1) and 5-nitro-2-(2H-tetrazol-5-yl)-2H-1,2,3-triazol-4-amine (C2). The results reveal that regioisomerism significantly modifies electron delocalization and molecular polarization. Compared with C1, C2 exhibits a smaller HOMO-LUMO gap (4.023 vs. 4.892 eV), higher softness, and stronger electrostatic polarization, indicating greater electronic activity and EEF responsiveness. Moreover, positive EEFs reduce the initial decomposition barriers of both isomers and promote hydrogen transfer as the dominant decomposition pathway, with the barrier decreasing by 13.3 kcal/mol for C1 and 14.7 kcal/mol for C2 under + 0.01 a.u. These findings clarify the synergistic role of regioisomerism and EEFs in regulating the stability and decomposition mechanisms of triazole-based energetic materials, providing theoretical guidance for the molecular design of low-sensitivity energetic compounds.

All calculations were performed using Gaussian 16. Geometry optimizations and frequency analyses were carried out at the B3LYP/6-311G** level, while thermal decomposition pathways were investigated at the M06-2X/def2-TZVPP level. All transition states were confirmed by a single imaginary frequency and verified by IRC calculations. Gibbs free energies were calculated using Shermo. External electric fields of 0.00, ± 0.005, and ± 0.01 a.u. were applied along the X direction. Wavefunction analyses were performed using Multiwfn, and molecular visualizations were generated with VMD.