New cage super insensitive high energy materials constructed by the Diels-Alder reaction based on nitroazoles: A DFT study

Abstract

In this work, seven series of new advanced cage insensitive high energy materials were constructed by one step of Diels-Alder reactions, using nitroazoles and aminoethylenes as dienes and dienophiles, respectively. The detailed reaction direction, reaction type and reaction barrier of Diels-Alder reactions were investigated by DFT computations, and found that most of dienes are most possibly to react with tetraaminoethylene though the inverse Diels-Alder reaction with low energy barrier, while this is the neutral one for the rest dienes. Then, based on selected dienes and dienophiles, seven series of new cage energetic compounds were constructed. Their structures, detonation properties and impact sensitivity were studied by DFT and ESP methods. The results showed that there are 8 optimal compounds (PA2, PB2, PC1, PC2, PD1, PD2, PE1, PF1) have both higher energy and lower sensitivity than one famous and widely used insensitive energetic compound trinitrotoluene, and may be used as potential advanced insensitive energetic compounds. In addition, the NO2 group was found to obviously reduce the reaction energy barrier and promote the Diels-Alder reaction. It increased the density and oxygen balance to improve the detonation properties significantly, but it also increased the impact sensitivity by increasing the positive ESP value and centralizing positive ESP in less regions. This study may be helpful for developing new advanced insensitive high energy materials from new design and synthesis perspectives.