Ring closure of polynitroazoles via an N,N′-alkylene bridge: towards high thermally stable energetic compounds
High thermal stability is one of the important factors in the design of high-performance insensitive energetic compounds. A straightforward synthesis of tricyclic energetic molecules (2, 3, 5 and 6) has been developed through bridging ethylene-/propylene-moieties featuring two polynitroazoles. Remarkably, such ring closure reactions lead to higher thermal stability. In addition, the influence of 4,4′,5,5′-tetranitro-2H,2′H-3,3′-bipyrazole (1) and 5,5′-dinitro-2H,2′H-3,3′-bi-1,2,4-triazole (4) with or in the absence of an N,N′-alkylene bridge on the structural and electrostatic potentials (ESP) was established theoretically. The high thermal stability and good detonation properties may make these materials useful as replacements for trinitrotoluene (TNT).