FOX-7 derivatives with enhanced detonation performance: a theoretical screening from molecular design to electronic...

Balancing high detonation performance with low mechanical sensitivity remains a key challenge in energetic materials. FOX-7, featuring low sensitivity and moderate energy, serves as an ideal molecular platform. In this study, a series of FOX-7 derivatives bearing nitrogen-rich heterocycles and energetic substituents were designed and evaluated by DFT calculations to enhance detonation performance while preserving acceptable safety. Most designed compounds show positive solid-phase heats of formation, with C6 (729.37 kJ/mol) and G1 (590.10 kJ/mol) being the highest. Nitramino (-NHNO2) and azido (-N3) groups significantly boost detonation performance. H6 exhibits the best theoretical detonation parameters: D = 8.95 km/s and P = 37.35 GPa, 1.36% and 7.66% higher than RDX, respectively. G6, and F5 also show excellent performance. IRI analysis reveals that nitramino strengthens intramolecular H-bonding, enhancing stability. Azido enlarges positive ESP regions, correlating with higher impact sensitivity, while hydrazino (-NHNH2) promotes H-bond networks and lowers sensitivity (e.g., G1, H50 = 56.36 cm). Combining tetrazine/tetrazole rings with nitramino, azido, or hydrazino groups offers a promising strategy to achieve high detonation performance with acceptable sensitivity. F6, H6, G6, F5, and G1 are identified as the most promising candidates for future synthesis and validation.

All calculations were performed with Gaussian 16 using density functional theory. Initial geometry optimizations were carried out at the M062x/6-311g(d,p) level, followed by single-point energy calculations at the M062x/def2TZVPP level.