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The evolution of energetic materials science presents new challenging tasks associated with the creation of advanced technologies for sustainable development of the future. In this work, a set of new heat-resistant high-energy materials incorporating the polynitrophenyl-1,2,5-oxadiazole scaffold enriched with azo/azoxy moieties have been designed and synthesized. Due to a smart combination of explosophoric groups and 1,2,5-oxadiazole rings, the prepared high-energy substances have excellent thermal stability (up to 300 °C), good densities (up to 1.75 g cm -3 ), high enthalpies of formation (340-538 kJ mol -1 ), and high combined nitrogen-oxygen content (63-68%). In-depth structural analysis revealed the presence of strong intra- and intermolecular hydrogen bonds in aminodinitrophenyl derivatives, which in combination with the small deviation of electrostatic potential values explains the low mechanical sensitivity of these materials. At the same time, trinitrophenyl-1,2,5-oxadiazoles incorporating three adjacent non-coplanar nitro groups demonstrated higher sensitivity to impact, albeit retaining complete insensitivity to friction. The overall performance of the thus prepared high-energy substances exceeds that of the known heat-resistant explosive hexanitrostilbene. Therefore, the newly synthesized family of energetic polynitrophenyl-1,2,5-oxadiazoles provides a fruitful foundation for the creation of the advanced heat-resistant energetic materials of the future.

A majority of known and newly synthesized energetic materials comprise polynitrogen or nitrogen-oxygen heterocycles with various explosophores. However, available structural combinations of these organic scaffolds are finite and are about to reach their limits. Herein, we present the design and synthesis of a series of sulfur-containing polyazole structures comprising 1,3,4-thiadiazole and furazan rings linked by C-C bonds and enriched with energetic nitro and azo functionalities. In terms of detonation performance, all synthesized 1,3,4-thiadiazole-furazan assemblies ( D = 7.7-7.9 km s -1 ; P = 26-28 GPa) lie between the powerful explosive TATB ( D = 8.0 km s -1 ; P = 31 GPa) and melt-cast material TNT ( D = 6.9 km s -1 ; P = 23 GPa). In the synthesized series, azo-bridged derivative 5 seems to be most practically interesting, as it combines a relatively high energetic performance ( D = 7.9 km s -1 ; P = 28 GPa), a very high thermal stability (271 °C), and insensitivity to friction. By these functional properties, 5 outperforms the benchmark heat-resistant explosive hexanitrostilbene (HNS). To the best of our knowledge, this is the first example of an energetic alliance of furazan and 1,3,4-thiadiazole scaffolds and a rare case of sulfur-containing high-energy materials, which can certainly be considered as an evolutionary step in energetic materials science.

A straightforward synthesis of a series of previously unknown N -(1,2,5-oxadiazolyl)hydrazones through the diazotization/reduction/condensation cascade of amino-1,2,5-oxadiazoles was accomplished. The described protocol was suitable for a wide array of target hydrazones, which were prepared in good to high yields under smooth reaction conditions with very good functional group tolerance. Importantly, the presented approach unveils a direct route to in situ generation of previously inaccessible (1,2,5-oxadiazolyl)hydrazines. In addition, a first example of the ionic structure incorporating a protonated hydrazone motif linked to the 1,2,5-oxadiazole 2-oxide subunit was synthesized, indicating the stability of prepared compounds toward acid-promoted hydrolysis. Overall, this method provides a direct access to the isosteric analogues of drug candidates for treatment of various neglected diseases, thus enabling their potential application in medicinal chemistry and drug design.