Research on the thermal stability of nitroform compounds remains relatively scarce, while cutting-edge reports on nitroform-based energetic materials have been increasingly emerging in recent years. In particular, thermal stability research, as a crucial indicator for the safety of nitroform compounds, deserves significant attention. Hence, the thermal stability of three chain nitroform-based bis-(1,2,4-oxadiazole) derivatives with nonlinkage, methylene and azo linkages was systematically investigated via bond order analysis, thermal decomposition calculations, electrostatic potential (ESP) mapping and frontier molecular orbital (FMO) analysis. Our results indicate that in nitroform compounds, the azo linkage may contribute to enhanced thermal stability, which is tentatively supported by its higher calculated ring-opening energy barrier (61.28 kcal mol-1), uniform ESP distribution (ESP deviation = 0.241) and enlarged HOMO-LUMO gap (9.32 eV). In contrast, the methylene linkage appears to reduce thermal stability, likely due to its poor structural symmetry and the lower ring-opening energy barrier. These findings demonstrate that azo linkages offer a dual advantage:improving thermal stability while increasing nitrogen content, providing a valuable design principle for next-generation chain nitroform-based energetic materials.
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