Isomerism-driven design of unsymmetric triazine-based energetic materials: Unlocking enhanced energetic performance, safety and stability

The triazine backbone serves as a crucial heterocyclic scaffold in the development of energetic materials due to its high nitrogen (52%) and energy content (223 kJ/mol). Additionally, it functions as an environmentally benign component, releasing a significant amount of gaseous products upon decomposition. In this study, three energetic compounds featuring -NH- bridged 1,2,4-ditriazine (unsymmetric triazine) backbone were computationally designed by introducing isomerism in the previously reported -NH- bridged 1,3,5-ditriazine backbone (symmetric triazine). Various explosophoric groups such as -NO2, -NH2, and -N3 were introduced into the backbones to improve performance and safety characteristics. All of the designed triazine derivatives were optimized and their energies were computed at the M06–2X/def2-TZVPP level of theory. The sensitivity of the designed triazine compounds was assessed through impact sensitivity (h50), balance parameter (ν) in molecular surface electrostatic potentials, free void space in the crystal lattice (∆V), and bond dissociation energy. The aromaticity and stability of the energetic compounds were evaluated using multicentre bond analysis, the AV1245 study, the molecular planarity parameter, span of deviation from plane, localised orbital locator, sphericity, variance in electrostatic surface potentials, and the skewness parameters. Among the designed triazine derivatives, nitro compound (B1) exhibits a high positive heat of formation (601.8 kJ/mol), dense packing (1.84 g/cm3), high detonation pressure (34.99 GPa), detonation velocity (8.91 km/s), and detonation temperature (4292 K), surpassing the energetic performance of RDX. Replacing the symmetric triazine with an unsymmetric unit results in an improvement in the heat of formation, detonation parameters, aromaticity, and sensitivity, representing a valuable approach for designing new energetic materials.