A unique approach to alter the properties of existing energetic materials through cocrystallization is presented. The structure and properties of 17 new cocrystals of the benchmark energetic material 2,4,6-trinitrotoluene (TNT) are elucidated. The donor−acceptor π−π interaction represents a reliable supramolecular synthon for the formation of cocrystals with this aromatic energetic material. When present, amine−nitro interactions direct secondary packing in these crystals. A detailed study of the cocrystals formed reveals an alteration of key properties including density, packing coefficient, melting point, and decomposition temperature. Cocrystallization provides the opportunity to tune properties of existing energetics to create superior materials and provides a complementary alternative to traditional methods that focus primarily on the synthesis of new compounds and/or the discovery of polymorphs with the most attractive properties.

Cocrystal Engineering of a Prototype Energetic Material: Supramolecular Chemistry of 2,4,6-Trinitrotoluene

Co-crystallisation is proposed as an effective method to adapt the physico-chemical properties of energetic materials, thus presenting the opportunity to fine-tune performance characteristics at the molecular level. This is illustrated by the characterisation of four co-crystals of the high explosive CL-20.

https://www.pure.ed.ac.uk/ws/files/11803311/Crystal_engineering_of_energetic_materials_Co_crystals_of_CL_20.pdf

Crystal engineering of energetic materials: Co-crystals of CL-20

Energetic materials (energetics), including explosives, propellants, and pyrotechnics, are an important class of materials for which performance depends critically on solid-state properties such as density and stability. Cocrystallization is emerging as a strategy to enhance materials properties of new and existing energetics; however, few examples exist where the principles to enable the successful engineering of such cocrystals have been delineated. To address this need, the cocrystallization of 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX), a powerful and widely used explosive, was investigated. Seven cocrystals of HMX were structurally elucidated using single crystal X-ray diffraction. These cocrystal structures, in addition to three previously reported structures, reveal at least three distinct structural motifs by which HMX cocrystals form, each dictated by the electronic character and size of the cocrystal former. From these structures, general trends emerge having direct implications for coc...

Cocrystals of 1,3,5,7-Tetranitro-1,3,5,7-tetrazacyclooctane (HMX)

Potentiometric Titrations Based on Ion-Pair Formation

A novel 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX)/pyridine-N-oxide (PNO) cocrystal at 1:1 molar ratio was synthesized by a solvent evaporation method, and its crystal structure was determined using X-ray diffraction (XRD). It crystallizes in the orthorhombic system with the Pbcn space group and cell parameters a = 12.712(3)A, b = 9.315(3)A, c = 12.909(3)A. In addition, detonation performance of this cocrystal was estimated. The predicted detonation velocity and detonation pressure of this cocrystal are 7.47 km/s and 23.20 GPa, respectively, suggesting that it is less powerful than β-HMX. Finally, density functional theory, involving binding energy, atoms in molecule (AIM) theory, natural bond orbital (NBO) analysis, band structure, and density of states, was adopted to characterize the driving forces for the formation of this cocrystal. The results show that driving forces are dominated by the interactions between O atoms of PNO and methylene groups of HMX. It is expected that this research pro...

Synthesis, Characterization, Detonation Performance, and DFT Calculation of HMX/PNO Cocrystal Explosive

A new series of relatively stable adducts of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) with derivatives of pyridine-N-oxide were prepared. In addition, relative stable new adducts of HMX were prepared with 5-membered, 6-membered, and condensed-ring heterocyclic compounds. Most of the adduct-forming compounds (AFC's) contain an oxygen and/or nitrogen heteroatom, while several contain a sulfur heteroatom. Most of the adducts are equimolar with HMX; however, several contain 2 moles of AFC per mole of HMX and other ratios of AFC:HMX. Some properties of the new adducts are presented.

New adducts of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX)

Relatively stable equimolar adducts of 1,3,5-trinitro-1,3,5-triazacyclohexane were prepared with 2,6-lutidine-N-oxide, 4-hydroxy-1-butanesulfonic acid δ-sultone (1,4-butane sultone), and 2,2,6,6-tetramethyl-4-piperidone-1-oxyl. Only the last adduct is selective for RDX; the others also form adducts with 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane. A very labile RDX adduct is formed with tetrahydrothiophene-1-oxide. Some properties of the new adducts are presented.

New adducts of 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX)

A new unstable equimolar adduct of hexahydro-1,3,5-trinitro-1,3,5-triazine was formed with 6-hexanolactone (ϵ-caprolactone). Some properties of the adduct are presented.



Eine neue Additionsverbindung von Hexahydro-1,3,5-trinitro-1,3,5-triazin (RDX) mit ϵ-Caprolacton



Eine neue, nichtstabile, aquimolare Additionsverbindung von RDX wurde erhalten mit 6-Hexanolacton (ϵ-Caprolacton). Einige Eigenschaften der Additionsverbindung werden vorgestellt.



Un nouveau compose par addition de l'hexogene et de l'ϵ-caprolactone



On a trouve un nouveau compose equimolaire, instable resultant d'une reaction d'addition entre l'hexogene et la 6-hexanolactone (ϵ-caprolactone). On presente quelques proprietes de ce compose par addition.

A hexahydro‐1,3,5‐trinitro‐l,3,5‐triazine (RDX): ϵ‐caprolactone adduct

Ammonium dinitrotriazole has been assayed by nonaqueous titration as an acid in dimethylsulfoxide versus tetrabutylammonium hydroxide. It can also be assayed by nonaqueous titration as a base in glacial acetic acid versus perchloric acid in glacial acetic acid. In mixtures with ammonium nitrate, ammonium dinitrotriazole can be determined by potentiometric titration in aqueous solution versus cetylpyridinium chloride.

The Assay of 1‐Ammonium‐3,5‐Dinitro‐1,2,4‐Triazole and its determination in mixtures with ammonium nitrate

Ammonium nitrate and ethylenediamine dinitrate in a composite have been determined by potentiometric titration with standard base after reaction with formaldehyde Ethylenediamine dinitrate yields two breaks, while ammonium nitrate exhibits only a single potentiometric break Both components can therefore be resolved The first potentiometric break is a measure of the ethylenediamine dinitrate content, while the second break is a measure of the sum of the components

W. Selig

Papers

New adducts of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX)

New adducts of 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX)

A hexahydro‐1,3,5‐trinitro‐l,3,5‐triazine (RDX): ϵ‐caprolactone adduct

The Assay of 1‐Ammonium‐3,5‐Dinitro‐1,2,4‐Triazole and its determination in mixtures with ammonium nitrate

The assay of ammonium nitrate and ethylenediamine dinitrate