Unveiling the potential of high-energy heat-resistant pyrazine, pyrimidine and pyridazine substituted tetranitrodibenzo-tetraazapentalene (TACOT) derivatives.

CONTEXT: Nitrogen-enriched aromatic fused heterocycles are a cornerstone of next-generation energetic materials, which are highly sought after for their high density and heat of formation. In this work, we present a computational design of six hydrogen-free energetic compounds based on heat-resistant, highly stable isomeric tetranitro-1,3a,6,6a-dibenzotetraazapentalene (y-TACOT) and tetranitro-1,3a,4,6a-dibenzotetraazapentalene (z-TACOT) frameworks, aiming to balance performance and sensitivity. To enhance the performance and energy content of the y-TACOT and z-TACOT frameworks while preserving their thermal stability and sensitivity, the two fused benzene rings in their structures were replaced with pyrazine, pyrimidine, and pyridazine. All the designed tetranitrodibenzo-tetraazapentalene (TACOT) derivatives are predicted to possess high enthalpies of formation (> 774 kJ/mol), high density (> 1.86 g/cm3), superior detonation pressure (> 33.15 GPa), velocity (> 8818 m/s), heat of detonation (> 1432 cal/g), and high strength of C-NO2 bonds (> 200 kJ/mol). Analysis of aromaticity, molecular planarity, and sphericity of the designed compounds yielded results comparable to those of parent y-TACOT and z-TACOT compounds, suggesting they will likely preserve key structural properties. With their collective profile of high-energy density, thermal stability, and low sensitivity, particularly evident in the pyridazine-based analogues, these compounds are promising candidates for next-generation heat-resistant applications with balanced performance and stability.

METHODS: The optimization and energy calculations of designed tetracyclic compounds were carried out at the B3LYP/6-311G(d,p) level of theory, utilizing the Gaussian 09 software package. The molecular surface properties were analyzed using Multiwfn. The EXPLO5 (V7.01.01) thermochemical code was used to predict the detonation properties.