Design of New Bridge-Ring Energetic Compounds Obtained by Diels–Alder Reactions of Tetranitroethylene Dienophile

The density functional theory method was employed to calculate three-dimensional structures for a series of novel explosophores. The design of new molecules (DA1-DA12) was based on the bridge-ring structures that could be formed via Diels-Alder (DA) reaction of selected nitrogen-rich dienes and tetranitroethylene dienophile. The feasibility of the proposed DA reactions was predicted on the basis of the molecular orbital theory. The strong interactions between the HOMO of dienes, with electron-donating groups (Diene2, Diene6, and Diene8), and the LUMO of tetranitroethylene dienophile suggested thermodynamically favorable formation of the desired DA reaction products. In addition to molecular structures of the explored DA compounds, their physicochemical and energetic properties were also calculated in detail. Due to compact bridge-ring structures, new energetic molecules have highly positive heats of formation (up to 1124.90 kJ·mol-1) and high densities (up to 2.04 g·cm-3). Also, as a result of all-right ratios of nitrogen and oxygen, most of the new compounds possess high detonation velocities (8.28-10.02 km·s-1) and high detonation pressures (30.87-47.83 GPa). Energetic compounds DA1, DA4, and DA12 exhibit a superior detonation performance over widely used HMX explosive, and DA5, DA7, and DA10 could be comparable to the state-of-the-art CL-20 and ONC explosives. Our proposed designs and synthetic methodology should provide a platform for the development of novel energetic materials with superior performance.