A comparative study of bridged 1,2,4-oxazolones and their derivatives

For energetic compounds, a slight difference in their molecular structures can result in a tremendous difference in their properties. Compounds with similar structures but exhibiting big difference in their physicochemical properties (such as density and detonation properties) are of interest to the researchers. The understanding of the reason causes the difference in their properties is important for designing new energetic compounds with improved performances. In this study, the structural and physicochemical properties of 3,3′-bis-1,2,4-oxadiazole-5,5′-dione (1) and 3,3′-azo-1,2,4-oxadiazole-5,5′-dione (2) and their derivatives were presented. All of the synthesized compounds were fully characterized, the comparative studies showed that 1 and its ionic derivatives were found to exhibit higher detonation velocities and pressures as well as higher densities than their corresponding azo linkage analogs. The crystal structures for the two neutral compounds were compared by Hirshfeld surface and non-covalent interaction analyses. The results indicate that a high packing coefficient and extensive π-π stacking interactions are two major reasons for 1 exhibiting better physicochemical and energetic properties.