Structure, Physicochemical Properties, and Density Functional Theory Calculation of High-Energy-Density Materials Constructed with Intermolecular Interaction: Nitro Group Charge Determines Sensitivity

Abstract

Four nitro-containing energetic compounds, cocrystal of AT·DNBA (1), salt of MA·DNSA (2), salt of AG·DNBA·H2O (3), and salt of DAT·DNSA H2O (4), are synthesized and structurally characterized based on supramolecular interactions (AT, 4-amino-1,2,4-triazole; DNBA, 3,5-dinitrobenzoic acid; MA, melamine; DNSA, 3,5-dinitrosalicylic acid; AG, amino guanidine; DAT, 3,5-diamino-1,2,4-triazole). The physicochemical properties of the compounds are theoretically and experimentally investigated in detail. The optimized structures, molecular total energies, frontier orbit energies, and charge densities of 1–4 are calculated by theoretical methods. The experimental results indicate that all compounds exhibit good thermostability and low sensitivity. It is worth noting that the values of impact sensitivity are measured to be 30, >40, 38, and >40 J for 1, 2, 3, and 4, respectively, which correspond well to the order of nitro group charge (QNitro) calculated by density functional theory. The detonation performances of 1–4 are discussed; in particular, 1 and 2 exhibit heats of detonation (2.191 kcal g–1 for 1 and 2.214 kcal g–1 for 2) superior to those of classical nitro-rich compounds. In addition, the nonisothermal thermokinetic parameters are obtained by Kissinger and Ozawa methods, and the standard molar enthalpies of formation are calculated from the determination of constant volume combustion energies.