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The standard state enthalpy of formation and the enthalpy of sublimation are essential thermochemical parameters determining the performance and application prospects of energetic materials. Direct experimental measurements of these properties...

Several energy-rich bifuroxans incorporating nitro and azido functionalities have been synthesized and thoroughly characterized by IR and multinuclear NMR spectroscopy, elemental analyses, single-crystal X-ray diffraction, and differential scanning calorimetry. N-oxide regiochemistry was employed to design the tunable azido(nitro)bifuroxans with different physicochemical and energetic properties. All synthesized compounds have high enthalpies of formation (449−777 kJ mol −1 ) and attractive performances, as evidenced by the high detonation velocities (8.95−9.75 km s −1 ) and Champan−Jouguet pressures (35−45 GPa). The most powerful energetic material in this series is 4,4′-dinitro-3,3′-bifuroxan. This hydrogen-free molecule (C 4 N 6 O 8 ) exhibits an outstanding heat of explosion value of 15.3 kJ cm −1 , far exceeding the top energetic material hexanitrohexaazaisowurtzitane CL-20. At the same time, the impact and friction sensitivities of 4,4′-dinitro-3,3′-bifuroxan were deemed acceptable for practical use. Overall, 4,4′-dinitro-3,3′-bifuroxan breaks a general trend called the "energy-sensitivity rule", which describes a linear increase of the mechanical sensitivity with a growth of the energetic content of the molecule, and, thus, offers great promise for future applications.

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A reliable kinetic description of the thermal stability of energetic materials (EM) is very important for safety and storage-related problems. Among other related issues, autocatalysis very often complicates the decomposition...

Cocrystal design is an important and well-developed approach in the pharmaceutical industry. Energetic materials can be thought of as unique and challenging objects for cocrystal engineering since abundant explosophoric functionalities prevent exploiting common supramolecular synthons. Screening of cocrystal formation using thermal analysis methods is investigated. A few approaches from the literature are combined in a single procedure that allows for automation, high-throughput screening, and the usage of milligrams of material. To estimate the accuracy of the screening procedure, we compiled available literature data on 213 cocrystals with energetic or very similar to energetic materials. The recommended procedure can detect cocrystal formation in 75% cases (with no false positives), according to a smaller sample data set of 28 cocrystal-forming systems. The procedure was then used to screen for novel cocrystals among several acidic energetic materials, ammonium and hydroxylammonium energetic salts, 3-nitro-1,2,4-triazole as a coformers, and 13 cocrystals were discovered. Then, using the traditional solution procedure, eight novel cocrystals were prepared, and their X-ray structures were reported. One of the cocrystals discovered, a complex of promising energetic material, dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (also known as TKX-50) with 18-crown-6, is the first cocrystal of TKX-50 with a reported X-ray structure so far. Overall, we present a unified procedure of thermal screening for cocrystals and salts; benchmarking on challenging objects for cocrystal design (energetic materials) shows its high performance.

In the present work, we studied in detail the thermochemistry, thermal stability, mechanical sensitivity, and detonation performance for 20 nitro-, cyano-, and methyl derivatives of 1,2,5-oxadiazole-2-oxide (furoxan), along with their bis-derivatives. For all species studied, we also determined the reliable values of the gas-phase formation enthalpies using highly accurate multilevel procedures W2-F12 and/or W1-F12 in conjunction with the atomization energy approach and isodesmic reactions with the domain-based local pair natural orbital (DLPNO) modifications of the coupled-cluster techniques. Apart from this, we proposed reliable benchmark values of the formation enthalpies of furoxan and a number of its (azo)bis-derivatives. Additionally, we reported the previously unknown crystal structure of 3-cyano-4-nitrofuroxan. Among the monocyclic compounds, 3-nitro-4-cyclopropyl and dicyano derivatives of furoxan outperformed trinitrotoluene, a benchmark melt-cast explosive, exhibited decent thermal stability (decomposition temperature >200 °C) and insensitivity to mechanical stimuli while having notable volatility and low melting points. In turn, 4,4′-azobis-dicarbamoyl furoxan is proposed as a substitute of pentaerythritol tetranitrate, a benchmark brisant high explosive. Finally, the application prospects of 3,3′-azobis-dinitro furoxan, one of the most powerful energetic materials synthesized up to date, are limited due to the tremendously high mechanical sensitivity of this compound. Overall, the investigated derivatives of furoxan comprise multipurpose green energetic materials, including primary, secondary, melt-cast, low-sensitive explosives, and an energetic liquid.