Energetic azo compounds based on 2,2′, 4,4′, 6,6′- hexanitroazobenzene: Structures, detonation performance, and sensitivity.

We present density functional theory (DFT) calculations and analysis of some substituted 2,2′, 4,4′, 6,6′- hexanitroazobenzene (HNAB). Geometries of all compounds have been optimized employing by B3LYP method in conjunction with 6-31G** basis set. The heat of formation (Δ f H) is evaluated using isodesmic reaction paths. Density and detonation characteristics including detonation velocity D , detonation pressure P , and detonation energy Q were researched by Kamlet-Jacob equation. We also include study and discuss the relation between sensitivity and molecular/electronic structures. The trigger bonds in the pyrolysis process for HNAB derivatives were calculated and explored. The predicted results indicate that some designed azo bridging (–N N–) compounds outperform traditional energetic materials and may be potential candidates for high-energy materials. [Display omitted] • Substituent effects on the properties related to detonation performance and sensitivity for 2,2′,4,4′,6,6′-hexanitroazobenzene (HNAB) derivatives is proposed. • The sensitivity of HNAB derivatives is explored with molecular/electronic properties. • Several interrelationships of HNAB derivatives is supposed that relate the detonation performance with measured or predicted molecular/electronic properties. Density functional theory (DFT) has been applied to explore the general rules for structure design of azo compounds through energetic properties and stability. Structures of 2,2′, 4,4′, 6,6′- hexanitroazobenzene (HNAB) derivatives were designed and optimized using B3LYP /6-31G(d,p) level, and the heat of formation (Δ f H) were evaluated by constructing isodesmic reactions. Results reveal that the azo bridging (–N N–) is useful for increasing the heat of formation. Kamlet–Jacobs equations were employed to evaluate detonation performance, while the sensitivity was explored by correlating with the bond dissociation energy (BDE), electronic structural parameters (E HOMO , E LUMO , and Δ E LUMO-HOMO), oxygen balance (OB), and charges on nitro group (Q NO2). According to our calculations, some designed HNAB derivatives possess interesting properties, such as good detonation performance and high stability, even beyond RDX and HMX, revealing that the presence of azo bridging (–N N–) backbone together with the introduction of various energetic groups is a promising choice in the design of high energy density materials (HEDMs). [ABSTRACT FROM AUTHOR]