Design and performance evaluation of nitrogen-rich bis-six-membered fused ring energetic materials via density functional theory.

CONTEXT: Density functional theory (DFT) calculations at the M06-2X/def2-TZVP level were employed to design bis-six-membered nitrogen-rich fused ring energetic materials. Six neutral derivatives (I-2-4, I-3-4, I-3-5, II-2-4, II-3-4, and II-3-5) achieved energy densities exceeding 2.0 g/cm3, with energetic salts reaching unprecedented values up to 3.3 g/cm3. Non-covalent interaction isosurfaces quantified van der Waals forces in crystal packing, while decomposition pathway simulations for II-3-2 identified a low O-NO2 BDE (20.24 kcal/mol) coexisting with high thermal stability ( T bp = 765.3 °C), governed by autocatalytic kinetics ( Δ G = 24.7 kcal/mol and Δ G = 8.44 kcal/mol). The DFT-derived performance matrix ( ρ > 2.02 g/cm3, T bp > 600 °C, HOFs > 3500 kJ/mol) provides a transferable protocol for balancing energy and safety in molecular modeling of advanced energetics.

METHOD: The DFT-based geometric optimization and frequency analyses of the designed molecules were determined using M06-2x/def2-TZVP method at Gaussian 09 package suite of programs. The heats of formation (HOF) for all molecules were obtained using an atomization reaction. The kinetic energy ( Δ E HOMO - LUMO ), electrostatic potential (ESP), and other related calculations were computed using Multiwfn_3.8_dev software. The visualization of the weak interaction between dimers was accomplished using VMD 1.9.3 program.