Secondary Amine Boosting Intermolecular Interactions: Nitratoethyl and Azidoethyl Functional Bistetrazolylamine Scaffold with Low Sensitivity

Energetic materials based on the tetrazole scaffold have attracted significant attention because of their high heat of formation and high nitrogen content. Incorporating a functional group in the tetrazole ring is an efficient strategy to enhance performance and meet the requirements for practical use. In this work, a versatile and rare secondary amine group (−NH−) was employed to connnect bistetrazoles and form intermolecular interactions, aimed at reinforcing the thermal stability and decreasing sensitivity. Novel bis(2-(2-nitratoethyl)-tetrazol-5-yl)amine and bis(2-(2-azidoethyl)-tetrazol-5-yl)amine were designed and synthesized. Benefiting from the unique intermolecular interactions originating from secondary amine moiety, they possess excellent thermal stability ( 2, T d = 205.6 °C; 3, T d = 238.0 °C) and low sensitivity ( 2, IS = 5.0 J; 3, IS = 6.0 J), which are better than other energetic compounds with nitratoethyl and azidoethyl group-based tetrazole backbones. Moreover, the crystal structure analysis and thermal behavior results indicate that they are not hygroscopic, exhibiting great potential for practical use.