Density functional theory study on the structure and energy properties of high-energy-density materials based on trinitrophenyl azacyclic compounds.

CONTEXT: The synergistic enhancement of both energy and safety in energetic materials is importance. Conventional polynitroaromatics like (e.g., HNS, TATB) offer high thermal stability but limited energy density, while nitrogen‑rich heterocycles (e.g., diazoles, triazoles) possess high energy density yet suffer from high sensitivity and poor thermal stability. In this research, five polycyclic energetic structures were designed by combining thermally stable polynitrophenyl units with high‑energy five‑membered nitrogen‑rich heterocycles via imine bridges. Density functional theory (DFT) calculations systematically correlated their electronic/molecular microstructures (e.g., electron density distribution, geometry) with macroscopic properties including detonation velocity and density. All designed compounds exhibited outstanding explosive performance, with detonation velocities (Dv) of 7892-8618 m·s⁻1, detonation pressures (P) of 27.9-34.4 GPa, and high enthalpies of formation (380.82-719.52 kJ·mol⁻1). Compounds 2 and 3 performed particularly well, surpassing HNS (7612 m·s⁻1) and TATB (8144 m·s⁻1) in detonation velocity. Moreover, all compounds showed excellent impact resistance (h50, 26-37 cm), comparable to HMX and RDX. Overall, this work provides theoretical guidance and candidate structures for developing high‑energy, low‑sensitivity energetic materials with promising application potential.

METHOD: Theoretical calculations were performed using the Gaussian 09 software package. Structural geometric optimization and frequency analysis were all calculated using the DFT-B3LYP3 method with a 6-31G(d,p) basis set. Subsequently, the single-point energy of the pre-optimized structures was evaluated at DFT/B3LYP3/6-31G(d,p) levels. Electrostatic potential energy and other related calculations were performed using the spectrum analysis software Multiwfn_3.8_dev. Regional visualization was achieved through the VMD 1.9.3 program.