Optimizing the molecular structure and packing style of a crystal by intramolecular cyclization from picrylhydrazone to indazole

AbstractHigh explosives, blasting agents, propellants, and pyrotechnics are all metastable relative to reaction products and are termed energetic materials. They are thermodynamically unstable but the kinetics of decomposition at ambient conditions are sufficiently slow that they can be handled safely under controlled conditions. The ease with which an energetic material can be caused to undergo a violent reaction or detonation is called its sensitivity. Sensitivity tests for energetic materials are aimed at defining the response of the material to a specific situation, usually prompt shock initiation or a delayed reaction in an accident. The observed response is always due to a combination of the physical state and the molecular structure of the material. Modeling of any initiation process must consider both factors. The physical state of the material determines how and where the energy is deposited in the material. The molecular structure in the solid state determines the mechanism of decomposition of the material and the rate of energy release. Slower inherent reaction chemistry leads to longer reaction zones in detonation and inherently safer materials. Slower chemistry also requires hot spots involved in initiation to be hotter and to survive for longer periods of time. High thermal conductivity also leads to quenching of small hot spots and makes a material more difficult to initiate. Early endothermic decomposition chemistry also delays initiation by delaying heat release to support hot spot growth. The growth to violent reaction or detonation also depends on the nature of the early reaction products. If chemical intermediates are produced that drive further accelerating autocatalytic decomposition the initiation will grow rapidly to a violent reaction.

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Thermal decomposition of energetic materials. Part 9. A relationship of molecular structure and vibrations to decomposition: polynitro-3,3,7,7-tetrakis(trifluoromethyl)-2,4,6,8-tetraazabicyclo[3.3.0]octanes

The Journal of Physical Chemistry ◽

10.1021/j100403a024 ◽

1986 ◽

Vol 90 (12) ◽

pp. 2679-2682 ◽

Cited By ~ 40

Author(s):

T. B. Brill ◽

Y. Oyumi

Keyword(s):

Molecular Structure ◽

Thermal Decomposition ◽

Energetic Materials ◽

Relationship Of

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Isostructural rubidium and caesium 4-(3,5-dinitropyrazol-4-yl)-3,5-dinitropyrazolates: crystal engineering with polynitro energetic species

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989021010227 ◽

2021 ◽

Vol 77 (11) ◽

Author(s):

Kostiantyn V. Domasevitch ◽

Vira V. Ponomarova

Keyword(s):

Crystal Engineering ◽

Self Assembly ◽

Energetic Materials ◽

Lone Pair ◽

The Self ◽

Two Dimensional ◽

Modular Construction ◽

Dipole Interactions ◽

Hirshfeld Surfaces ◽

Counter Ions

In the structures of the title salts, poly[[μ4-4-(3,5-dinitropyrazol-4-yl)-3,5-dinitropyrazol-1-ido]rubidium], [Rb(C6HN8O8)] n , (1), and its isostructural caesium analogue [Cs(C6HN8O8) n , (2), two independent cations M1 and M2 (M = Rb, Cs) are situated on a crystallographic twofold axis and on a center of inversion, respectively. Mutual intermolecular hydrogen bonding between the conjugate 3,5-dinitopyrazole NH-donor and 3,5-dinitropyrazole N-acceptor sites of the anions [N...N = 2.785 (2) Å for (1) and 2.832 (3) Å for (2)] governs the self-assembly of the translation-related anions in a predictable fashion. Such one-component modular construction of the organic subtopology supports the utility of the crystal-engineering approach towards designing the structures of polynitro energetic materials. The anionic chains are further linked by multiple ion–dipole interactions involving the 12-coordinate cations bonded to two pyrazole N-atoms [Rb—N = 3.1285 (16), 3.2261 (16) Å; Cs—N = 3.369 (2), 3.401 (2) Å] and all of the eight nitro O-atoms [Rb—O = 2.8543 (15)–3.6985 (16) Å; Cs—O = 3.071 (2)–3.811 (2) Å]. The resulting ionic networks follow the CsCl topological archetype, with either metal or organic ions residing in an environment of eight counter-ions. Weak lone pair–π-hole interactions [pyrazole-N atoms to NO2 groups; N...N = 2.990 (3)–3.198 (3) Å] are also relevant to the packing. The Hirshfeld surfaces and percentage two-dimensional fingerprint plots for (1) and (2) are described.

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Sensitivity of Energetic Materials: Theoretical Relationships to Detonation Performance and Molecular Structure

Industrial & Engineering Chemistry Research ◽

10.1021/acs.iecr.7b02021 ◽

2017 ◽

Vol 56 (29) ◽

pp. 8191-8201 ◽

Cited By ~ 32

Author(s):

Didier Mathieu

Keyword(s):

Molecular Structure ◽

Energetic Materials ◽

Detonation Performance

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Probing impact of molecular structure on mechanical property and sensitivity of energetic materials by machine learning methods

Chemometrics and Intelligent Laboratory Systems ◽

10.1016/j.chemolab.2021.104331 ◽

2021 ◽

pp. 104331

Author(s):

Qianqian Deng ◽

Jing Hu ◽

Liying Wang ◽

Yijing Liu ◽

Yanzhi Guo ◽

...

Keyword(s):

Molecular Structure ◽

Machine Learning ◽

Mechanical Property ◽

Energetic Materials ◽

Learning Methods ◽

Machine Learning Methods

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Crystal Engineering: Strategies and Architectures

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768197008446 ◽

1997 ◽

Vol 53 (4) ◽

pp. 569-586 ◽

Cited By ~ 373

Author(s):

C. B. Aakeröy

Keyword(s):

Molecular Structure ◽

Crystal Engineering ◽

Crystal Packing ◽

Three Dimensional ◽

Structural Data ◽

Building Blocks ◽

Intermolecular Forces ◽

Design Strategies ◽

Playing Field ◽

Molecular Building Blocks

The area broadly described as crystal engineering is currently expanding at a brisk pace. Imaginative schemes for supramolecular synthesis, and correlations between molecular structure, crystal packing and physical properties are presented in the literature with increasing regularity. In practice, crystal engineering can be many different things; synthesis, statistical analysis of structural data, ab initio calculations etc. Consequently, we have been provided with a new playing field where chemists from traditionally unconnected parts of the spectrum have exchanged ideas, defined goals and made creative contributions to further progress not only in crystal engineering, but also in other disciplines of chemistry. Crystal engineering is delineated by the nature and structural consequences of intermolecular forces, and the way in which such interactions are utilized for controlling the assembly of molecular building blocks into infinite architectures. Although it is important to acknowledge that a crystal structure is the result of a subtle balance between a multitude of non-covalent forces, this article will focus on design strategies based upon the hydrogen bond and will present a range of approaches that have relied on the directionality and selectivity of such interactions in the synthesis of predictable one-, two- and three-dimensional motifs.

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