Substituent-directed tuning of energetic performance and sensitivity in tetrazolo[1,2,4]triazine-based high-energy materials: a computational investigation.

CONTEXT: A nitrogen-rich fused tetrazolo[1,2,4]triazine framework was employed as a rigid and highly conjugated energetic backbone to design six energetic derivatives (A1-A6) bearing amino (-NH2), nitramino (-NHNO2), nitro (-NO2), and mixed substituents. All tailored tetrazolo[1,2,4]triazine compounds exhibit high positive solid-phase heats of formation (459.19-652.40 kJ/mol), substantially exceeding those of TNT and RDX. Incorporation of oxygen-rich explosophoric groups progressively improves oxygen balance, density, and detonation performance, with compound A5 containing two -NO2 groups exhibiting the highest detonation velocity (9.18 km/s) and detonation pressure (38.3 GPa). Bond dissociation energy, electron localization, interaction region indicator, and quantum theory of atoms in molecules analyses reveal that substitution of -NH2, -NO2, and -NHNO2 groups strongly modulates bond strength, charge distribution, and intermolecular interactions. The fused tetrazolo[1,2,4]triazine framework retains aromaticity and π-electron delocalization despite functional group modification. Overall, the results demonstrate that mixed -NH2 and -NHNO2/-NO2 substitution on tetrazolo[1,2,4]triazine backbone provides an effective strategy for tuning the energy-performance-sensitivity balance, with amino groups favoring reduced sensitivity and nitro/nitramino groups enhancing energetic performance.

METHODS

The optimization and energy calculations of designed tetrazolo[1,2,4]triazine derivatives were performed at the B3LYP/6-311 + G(d,p) and M06-2X/def2-TZVPP levels of theory, utilizing the Gaussian 09 software package. The molecular surface properties were analyzed by employing Multiwfn software. The EXPLO5 (V7.01.01) thermochemical code was used to predict the detonation properties.