Characterization and properties of a novel energetic Co-crystal formed between 2,4,6-Trinitrophenol and 9-Bromoanthracene

Abstract

A 1:1 co-crystal of Picric acid and 9-Bromoanthracene were prepared by a solvent evaporation method. The structure of the co-crystal (PIC: BRA) was determined via single crystal and powder X-ray diffraction techniques. The diffraction data analysis revealed that the co-crystal is primarily formed through donor-acceptor π … π and face-to-face π-stacking interactions. The PIC: BRA co-crystal shows significantly reduced impact sensitivity relative to pure Picric acid. We find that PIC: BRA co-crystal arranges in layered motifs, while the pure Picric acid structure is composed of irregular, herringbone packing. The results showed that π-stacked structures in explosives, especially planar layers, are very helpful to not only to decrease their impact sensitivities but also to enhance their molecular stabilities. The physicochemical properties of the compounds are theoretically and experimentally examined in detail. The theoretical calculations confirm that the PIC-BRA co-crystal has equivalent energetic properties to Picric acid. This exhaustive study of co-crystallization has resulted in the alteration of vital properties including density, oxygen balance, melting point, decomposition temperature, crystal packing, HOMO-LUMO gaps and detonation performance (sensitivity, velocity, pressure). The acquired results highlight that co-crystallization provides the newly discovered energetic material with attractive properties, and is an effective way to modify existing energetic materials.