Construction of New Insensitive Explosives: Fused N₅-Chain N¹,N³,N⁵-(1,2,3,4-Tetrazole -5-Nitro)-1,3,5-Triamino-2,4,6-Trinitrobenzene Derivatives

<p>A series of N¹,N³,N⁵-(1,2,3,4-tetrazole-5-nitro)-1,3,5-triamino-2,4,6-trinitrobenzene derivatives containing fused N₅-chain were investigated theoretically. Density functional theory has been employed to calculate their geometric, electronic structures, band gaps, and heats of formation at the B3LYP/6-31G** level. The detonation performance was evaluated by using Kamlet-Jacobs equations based on the calculated densities and HOFs. The thermal stability of these compounds was investigated by bond dissociation energies, energy gaps and molecular electrostatic potentials. Results show that there are good linear relationships between detonation velocity, detonation pressure and the number of nitro groups. Most of the designed derivatives have higher detonation velocity (<i>D</i>), detonation pressure (<i>P</i>), and specific impulse (<i>I</i>_sp) than those of RDX. <i>D</i> and <i>I</i>_sp of molecule L even outperform those of CL-20. Some of the title molecules have higher <i>h</i>₅₀ (impact sensitivity) than RDX (except for D, H, L). According to the quantitative standard of energy and stability as insensitive high energetic materials (IHEMs), molecules I and J essentially satisfy this requirement. These results provide basic information for molecules design of novel IHEMs.</p

Bicyclic High-Energy and Low-Sensitivity Regioisomeric Energetic Compounds Based on Polynitrobenzene and Pyrazoles

With the development of synthetic methodology and crystallography of energetic materials, regiochemistry is becoming popular and vital in the design of versatile energetic compounds as well as in the thorough research on the relationship between structure and property. In this study, two regioisomeric bicyclic energetic compounds based on pyrazole and polynitrobenzene were synthesized simultaneously by a simple synthetic route, and the regioisomers could be purified by a facile approach. It is interesting to note that the ratio of the two compounds changed with temperature. From 80 to 110 °C, the proportion of compound 2 gradually enhanced with the increase in temperature. In addition, the nitramine product of compound 1 was also synthesized. The structural data of compounds 1, 2, and 3 were confirmed by X-ray single-crystal diffraction. The detonation velocities of the new compounds are in the range of 8436–8788 m s–1 and impact sensitivities are between 15 and 27.5 J, of which compounds 2 and 3 not only present superior sensitivities to those of the classical high-energy explosive RDX (7.5 J) but also exhibit comparable detonation velocities to the measured RDX powder (VD = 8796 m s–1), calculated by EXPLO5 as 8788 and 8526 m s–1, respectively. Moreover, compounds 1 and 2 show good thermal stability with decomposition temperatures up to 263 and 287 °C, which is higher than that of RDX (Tdec: 204 °C). All of the above information indicates that these compounds are high-energy, low-sensitivity energetic materials featuring prospective applications

Constructing Heat-Resistant and Insensitive Energetic Compounds with the Introduction of Cyano Group into Fused Pyrazolotriazine Skeleton

Fused pyrazolotriazine frameworks have been used to develop novel heat-resistant energetic compounds. Diazotization of 3,4-diamino-4-nitropyrazole (1) and 3-anmio-4,5-dinitropyrazole (ADNP) followed by treatment with malononitrile afford compounds 2 and 3, including fused pyrazolotriazine ring surrounded by amino and cyano groups, respectively. Compounds 2 and 3 were thoroughly characterized by multinuclear NMR spectroscopy, infrared spectroscopy, and elemental analysis. The molecular structures of 2 and 3 were further confirmed by single crystal X-ray diffraction with the densities of 1.794 and 1.817 g·cm–3 (298 K), respectively. Moreover, compounds 2 and 3 have low impact and friction sensitivities (IS > 50 J, FS > 324 N). In particularly, compound 2 possesses the crossing stacking mode and high onset decomposition temperature of 370 °C, whose comprehensive performances are better than those of (2,2′,4,4′,6,6′-hexanitrostilbene) HNS and (2,6-bis­(picrylamino)-3,5-dinitropyridine) PYX. The efficient method of malononitrile cyclization provides a new idea for the development of novel heat-resistant energetic compounds

Antioxidant-Based Lead Discovery for Cancer Chemoprevention: The Case of Resveratrol

Resveratrol is a well-known natural antioxidant and cancer chemopreventive agent that has attracted much interest in the past decade. Resveratrol-directed compounds were synthesized, and their antioxidant effects against reactive oxygen species (ROS)-induced DNA damage, their prooxidant effects on DNA damage in the presence cupric ions, and their cytotoxic and apoptosis-inducing effects on human promyelocytic leukemia (HL-60) cells were investigated in vitro. It was found that the compounds bearing o-diphenoxyl groups exhibited remarkably higher activities in inhibiting ROS-induced DNA damage, accelerating DNA damage in the presence cupric ions, and inducing apoptosis of HL-60 cells compared with the ones bearing no such groups. The detail mechanism of the structure−activity relationship was also studied by the oxidative product analysis of resveratrol and its analogues with galvinoxyl radical or cupric ions and UV−visible spectra change in the presence cupric ions. This study reveals a good and interesting correlation between antioxidant and prooxidant activity, as well as cytotoxicity and apoptosis-inducing activity against HL-60 cells, and provides an idea for designing antioxidant-based cancer chemoprevention agents