Crystal engineering of high explosives through lone pair-pi interactions: Insights for improving thermal safety

In this high-risk/high-reward study, we prepared complexes of a high explosive anion (picrate) with potentially explosive s-tetrazine-based ligands with the sole purpose of advancing the understanding of one of the weakest supramolecular forces: the lone pair-pi interaction. This is a proof-of-concept study showing how lone pair-pi contacts can be effectively used in crystal engineering, even of high explosives, and how the supramolecular architecture of the resulting crystalline phases influences their experimental thermokinetic properties. Herein we present XRD structures of 4 novel detonating compounds, all showcasing lone pair-pi interactions, their thermal characterization (DSC, TGA), including the correlation of experimental thermokinetic parameters with crystal packing, and in silico explosion properties. This last aspect is relevant for improving the safety of high-energy materials.

Automated summary

In this study, we prepared complexes of a high explosive anion (picrate) with potentially explosive s-tetrazine-based ligands to advance the understanding of the lone pair-pi interaction. By presenting XRD structures of 4 novel detonating compounds and studying their thermal and explosive properties, this research demonstrates the effectiveness of using lone pair-pi contacts in crystal engineering, even for high explosives, and highlights the importance of supramolecular architecture in determining their properties. The in silico explosion properties studied in this research also contribute to improving the safety of high-energy materials.