Molecular Dynamics Simulation of NTO/TNPyO Co-Crystals for Targeted Acidity Regulation of NTO.

3-Nitro-1,2,4-triazol-5-one (NTO) exhibits acid corrosion due to facile proton dissociation at the N4 site (pKa = 3.76), limiting practical applications. To mitigate this, we cocrystallized NTO with 2,4,6-trinitropyridine 1-oxide (TNPyO) using MATERIALS STUDIO 2023 software across stoichiometric ratios from 4:1 to 1:4. Supercell models for NTO/TNPyO were constructed. We employed the density functional theory and molecular dynamics methods to simulate the possibility of the existence of the cocrystal and analyze the intermolecular forces and variation in N4-H4 bond length in NTO. The stability, mechanical properties, and other characteristics of cocrystals were predicted. The study focused on reinforcing intermolecular hydrogen bonding to stabilize the N4-H4 group, raising the proton dissociation energy barrier, and inhibiting H+ release. This strategy resulted in a 2.8-unit pKa increase for the cocrystal compared to that of pure NTO, thereby attenuating NTO acidity. The detonation performance and products for pure NTO, TNPyO, and the cocrystal system were predicted with EXPLO-5 software. The results demonstrate interactions between NTO and TNPyO molecules, indicating cocrystal formation potential with an optimal 2:1 molar ratio, where the cocrystal shortens the N4-H4 bond length to enhance stability, prevents proton ionization, and suppresses acidity primarily through hydrogen bonding (validated statistically), electrostatic interactions, dispersion, and van der Waals forces; they have the potential to become novel noncorrosive, insensitive energetic materials that maintain low sensitivity and excellent mechanical and detonation properties.