Computational Design and Theoretical Evaluation of Novel Heterocyclic Energetic Materials Based on 5-H-Imidazo-[4,5-c]-Pyridazine and 1,2,4-Triazolo-[4,3-a]-Pyrazine Scaffolds.

Novel energetic materials based on 5-H-imidazo-[4,5-c]-pyridazine and 1,2,4-triazolo-[4,3-a]-pyrazine scaffolds, modified with explosophore groups (NO2, NHNO2, N3, and ONO2), were theoretically designed and evaluated by DFT at the B3LYP/def2-TZVPP // B3LYP/6-311G(d,p) level. Nitramino derivatives exhibited the highest chemical stability based on HOMO-LUMO gap analysis. Heat of formation followed the trend N3 > NO2 > NHNO2 > ONO2. Most imidazopyridazine derivatives exceeded RDX density, while all surpassed TNT. All derivatives showed superior detonation parameters over TNT, with 18 exceeding RDX performance. Impact sensitivity analysis revealed favorable safety profiles, with all di- and tri-substituted nitramines less sensitive than RDX. Mayer bond order analysis of all 88 compounds identified the trigger bonds for each compound and class, revealing distinct lability ranges for each explosophore:ONO2 (0.490-0.728), CNO2 (0.737-0.789), HNNO2 (0.784-0.892), CNHNO2 (0.917-0.944), and CN3 (1.018-1.102). Aromaticity analysis ( NICS 1 zz ) showed that explosophore substitution systematically reduces aromatic character relative to the unsubstituted scaffolds, a trend correlated with molecular electrostatic potential (MEP) redistribution and associated with higher density, heat of detonation, detonation velocity, and detonation pressure. After a combined analysis of detonation performance, impact sensitivity profiles, trigger bond lability, and bond dissociation enthalpies, three compounds (IA345, IA356, and TA356) emerged as the most promising candidates, exhibiting heat of formation > 303.7 kJ mol-1, oxygen balance > -28.2%, density > 1.85 g cm-3, detonation velocity > 8.76 km s-1, and detonation pressure > 33.17 GPa.