Design and Synthesis of a Series of Nitrogen-Rich Energetic Cocrystals of 5,5′-Dinitro‑2<i>H</i>,2<i>H</i>′‑3,3′-bi-1,2,4-triazole (DNBT)

A series of three energetic cocrystals containing 5,5′-dinitro-<i>2H</i>,2<i>H</i>′-3,3′-bi-1,2,4-triazole (DNBT) were obtained. These incorporate a class of energetic materials that has seen significant synthetic work, the azole family (tetrazoles, triazole, pyrazole, etc.), and yet have struggled to see broad application. A cocrystal was obtained with the triazole 5-amino-3-nitro-1<i>H</i>-1,2,4-triazole (ANTA) in a stoichiometry of 2:1 (ANTA:DNBT). Two cocrystals were obtained with the pyrazoles 1<i>H</i>,4<i>H</i>-3,6-dinitropyrazolo­[4,3-<i>c</i>]­pyrazole (DNPP) and 3,4-dinitropyrazole (3,4-DNP) in ratios of 1:1 (DNPP:DNBT) and 2:1 (3,4-DNP:DNBT). All three cocrystals, 2:1 ANTA/DNBT (<b>1</b>), 1:1 DNPP/DNBT (<b>2</b>), and 2:1 3,4-DNP/DNBT (<b>3</b>), have high densities (>1.800 g/cm³) and high predicted detonation velocities (>8000 m/s). In small-scale impact drop tests, cocrystals <b>1</b> and <b>2</b> were both found to be insensitive, whereas cocrystal <b>3</b> possesses sensitivity between that of its two pure components 3,4-DNP and DNBT. The hydrogen bonding motif of the three components with DNBT is preserved among all three cocrystals, and this observation suggests a generally useful motif to be employed in the development of other energetic–energetic cocrystals. These cocrystals represent an area of energetic materials that has yet to be explored for cocrystalline materials

Design and Synthesis of a Series of Nitrogen-Rich Energetic Cocrystals of 5,5′-Dinitro‑2<i>H</i>,2<i>H</i>′‑3,3′-bi-1,2,4-triazole (DNBT)

A series of three energetic cocrystals containing 5,5′-dinitro-<i>2H</i>,2<i>H</i>′-3,3′-bi-1,2,4-triazole (DNBT) were obtained. These incorporate a class of energetic materials that has seen significant synthetic work, the azole family (tetrazoles, triazole, pyrazole, etc.), and yet have struggled to see broad application. A cocrystal was obtained with the triazole 5-amino-3-nitro-1<i>H</i>-1,2,4-triazole (ANTA) in a stoichiometry of 2:1 (ANTA:DNBT). Two cocrystals were obtained with the pyrazoles 1<i>H</i>,4<i>H</i>-3,6-dinitropyrazolo­[4,3-<i>c</i>]­pyrazole (DNPP) and 3,4-dinitropyrazole (3,4-DNP) in ratios of 1:1 (DNPP:DNBT) and 2:1 (3,4-DNP:DNBT). All three cocrystals, 2:1 ANTA/DNBT (<b>1</b>), 1:1 DNPP/DNBT (<b>2</b>), and 2:1 3,4-DNP/DNBT (<b>3</b>), have high densities (>1.800 g/cm³) and high predicted detonation velocities (>8000 m/s). In small-scale impact drop tests, cocrystals <b>1</b> and <b>2</b> were both found to be insensitive, whereas cocrystal <b>3</b> possesses sensitivity between that of its two pure components 3,4-DNP and DNBT. The hydrogen bonding motif of the three components with DNBT is preserved among all three cocrystals, and this observation suggests a generally useful motif to be employed in the development of other energetic–energetic cocrystals. These cocrystals represent an area of energetic materials that has yet to be explored for cocrystalline materials

Design and Synthesis of a Series of Nitrogen-Rich Energetic Cocrystals of 5,5′-Dinitro‑2<i>H</i>,2<i>H</i>′‑3,3′-bi-1,2,4-triazole (DNBT)

A series of three energetic cocrystals containing 5,5′-dinitro-<i>2H</i>,2<i>H</i>′-3,3′-bi-1,2,4-triazole (DNBT) were obtained. These incorporate a class of energetic materials that has seen significant synthetic work, the azole family (tetrazoles, triazole, pyrazole, etc.), and yet have struggled to see broad application. A cocrystal was obtained with the triazole 5-amino-3-nitro-1<i>H</i>-1,2,4-triazole (ANTA) in a stoichiometry of 2:1 (ANTA:DNBT). Two cocrystals were obtained with the pyrazoles 1<i>H</i>,4<i>H</i>-3,6-dinitropyrazolo­[4,3-<i>c</i>]­pyrazole (DNPP) and 3,4-dinitropyrazole (3,4-DNP) in ratios of 1:1 (DNPP:DNBT) and 2:1 (3,4-DNP:DNBT). All three cocrystals, 2:1 ANTA/DNBT (<b>1</b>), 1:1 DNPP/DNBT (<b>2</b>), and 2:1 3,4-DNP/DNBT (<b>3</b>), have high densities (>1.800 g/cm³) and high predicted detonation velocities (>8000 m/s). In small-scale impact drop tests, cocrystals <b>1</b> and <b>2</b> were both found to be insensitive, whereas cocrystal <b>3</b> possesses sensitivity between that of its two pure components 3,4-DNP and DNBT. The hydrogen bonding motif of the three components with DNBT is preserved among all three cocrystals, and this observation suggests a generally useful motif to be employed in the development of other energetic–energetic cocrystals. These cocrystals represent an area of energetic materials that has yet to be explored for cocrystalline materials

Media 1: High-repetition-rate three-dimensional OH imaging using scanned planar laser-induced fluorescence system for multiphase combustion

Originally published in Applied Optics on 20 January 2014 (ao-53-3-316

Media 2: High-repetition-rate three-dimensional OH imaging using scanned planar laser-induced fluorescence system for multiphase combustion

Originally published in Applied Optics on 20 January 2014 (ao-53-3-316

Performance and Aging of Mn/MnO₂ as an Environmentally Friendly Energetic Time Delay Composition

The Mn/MnO₂ reactive system was investigated as a suitable replacement for the traditional W/BaCrO₄/KClO₄/diatomaceous earth delay composition. The delay performance, ignition sensitivity, and aging characteristics were examined in aluminum microchannels similar in diameter to common delay housings (4.7 mm). Stoichiometries with measured combustion temperatures between 1358 and 2113 K were self-sustaining with combustion velocities ranging from 2.4 to 7.3 mm s^–1. The Mn/MnO₂ system produced less gas than W/BaCrO₄/KClO₄/diatomaceous earth compositions allowing consideration for use in sealed delay housings. Accelerated aging at 70 °C and 30% relative humidity for 8 weeks resulted in no measurable loss of performance. Safety characterization showed that this composition is not sensitive to ignition by friction or electrostatic stimuli. The combustion products (as determined by X-ray diffraction) appear to be benign based on current regulations. Therefore, the Mn/MnO₂ system appears to be a suitable low gas-producing, nonsensitive, less toxic delay composition with good longevity

Fate and Toxicity of CuO Nanospheres and Nanorods used in Al/CuO Nanothermites Before and After Combustion

Although nanotechnology advancements should be fostered, the environmental health and safety (EHS) of nanoparticles used in technologies must be quantified simultaneously. However, most EHS studies assess the potential implications of the free nanoparticles which may not be directly applicable to the EHS of particles incorporated into in-use technologies. This investigation assessed the aquatic toxicological implications of copper oxide (CuO) nanospheres relative to CuO nanorods used in nanoenergetic applications to improve combustion. Particles were tested in both the as-received form and following combustion of a CuO/aluminum nanothermite. Results indicated nanospheres were more stable in water and slowly released ions, while higher surface area nanorods initially released more ions and were more toxic but generally less stable. After combustion, particles sintered into larger, micrometer-scale aggregates, which may lower toxicity potential to pelagic organisms due to deposition from water to sediment and reduced bioavailability after complexation with sediment organic matter. Whereas the larger nanothermite residues settled rapidly, implying lower persistence in water, their potential to release dissolved Cu was higher which led to greater toxicity to <i>Ceriodaphnia dubia</i> relative to parent CuO material (nanosphere or rod). This study illustrates the importance of considering the fate and toxicology of nanoparticles in context with their relevant in-use applications