Design of functionalized bridged 1,2,4-triazole N -oxides as high energy density materials and their comprehensive correlations

The demand for high energy density materials (HEDMs) remains a major challenge. Density functional theory (DFT) methods were employed to design a new family of bridged 1,2,4-triazole N-oxides by the manipulation of the linkage and oxygen-containing groups. The optimized geometry, electronic properties, energetic properties and sensitivities of new 40 molecules in this study were extensively evaluated. These designed compounds exhibit high densities (1.87-1.98 g cm-3), condensed-phase heat of formation values (457.31-986.40 kJ mol-1), impressive values for detonation velocity (9.28-9.49 km s-1) and detonation pressure (21.22-41.31 GPa). Their sensitivities (impact, electrostatic, and shock) were calculated and compared with 1,3,5-triamino-2,4,6-trinitrobenzene (TABT) and 4,6-dinitrobenzofuroxan (DNBF). Some new compounds 4,4′-trinitro-5,5′-bridged-bis-1,2,4-triazole-2,2′-diol (TN1-TN8) and 4,4′-dinitro-5,5′-ammonia-bis-1,2,4-triazole-2,2′-diol (DN3) were distinguished from this system, making them promising candidates for HEDMs. In addition, we found that the gas-relative parameters (detonation heat, oxygen balance, φ) were as important as the density, which were highly correlated to the detonation properties (P, D). Their comprehensive correlations should also be considered in the design of new energetic molecules.