Zwitterionic Energetic Materials: Synthesis, Structural Diversity and Energetic Properties

Abstract

Zwitterionic compounds are an emergent class of energetic materials and have gained synthetic interest of many in the recent years. Due to their better packing efficiencies and strong inter/intramolecular electrostatic interactions, they often ensue superior energetic properties than their salt analogues. A systematic review from the perspective of design, synthesis, and physicochemical properties evaluation of the zwitterionic energetic materials is presented. Depending on the parent ring(s) used for the synthesis and the type of moieties bearing positive and negative charges, different classes of energetic materials, such as primary explosives, secondary explosives, heat resistant explosives, oxidizers, etc., may result. The properties of some of the energetic zwitterionic compounds are also compared with analogous energetic salts. This review will encourage readers to explore the possibility of designing new zwitterionic energetic materials.

Insights into Structural and Energetic Features of 3,5-Dinitropyrazole-4-carboxylic Acid and Its Energetic Salts

“…Crystal engineering of energetic materials (EMs) involves understanding the correlation between molecular and crystal structures and utilizing this understanding to tailor EMs with the desired performance and suitable physical stability. − Since molecule and crystal structures are inherent properties of compounds, they remain unchanged under various temperature and pressure conditions. Therefore, improvement in the properties of energetic materials can be attained by targeting these intrinsic properties. − Numerous studies on crystal engineering of energetic materials have been carried out for traditional molecules, including single-component molecular and ionic crystals. These studies indicate that the energy-safety contradiction among energetic molecules can primarily be alleviated through three factors: high molecular stability, intermolecular interactions, and face-to-face π-stacking (layered stacking). − One such instance of a single-component molecular crystal is TATB (2,4,6-triamino-1,3,5-trinitrobenzene), characterized by its planar structure and stable alternating C–NO 2 and C–NH 2 bonds.…”