Syntheses, Crystal Structures, and Properties of Two Novel CL‐20‐based Cocrystals

Liu, Yujia; Lv, Penghao; Sun, Chia‐Chung; Pang, Siping

doi:10.1002/zaac.201900017

Cited by 16 publications

(11 citation statements)

References 39 publications

(35 reference statements)

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“…In addition, an interesting phenomenon is that multiple conformers of CL-20 or HMX are found in EMCCs. The CL-20-based EMCCs possess the largest population among the observed EMCCs except for a large quantity of energetic solvates of HMX. ,,,− This can be attributed to the remarkable detonation performance, while the rather high sensitivity requires an improvement of CL-20 itself. With regard to the molecular structure of CL-20, its cage frame is rigid, while its nitro groups can be swung readily, giving it a certain flexibility to implement the conformational transformation. , With respect to the CL-20 molecules in CL-20-based EMCCs, five types of conformers are found, including β, γ, η, ε, and ζ forms (Figure ).…”

Section: Intermolecular Interactions In Emccsmentioning

confidence: 99%

Review of the Intermolecular Interactions in Energetic Molecular Cocrystals

Liu

Wei

Zhang

2020

Crystal Growth & Design

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Energetic cocrystallization is thriving now and presents a promising perspective to create new energetic materials (EMs). In comparison with the single-component EMs, the creation of energetic cocrystals exhibits a greater significance of crystal engineering, whose central scientific issue is intermolecular interaction. This article reviews the current progress in studying the intermolecular interactions of energetic molecular cocrystals (EMCCs), as well as the molecular stacking and the thermodynamics for EMCC formation. The intermolecular interactions include hydrogen bonding (HB), π interactions, and halogen bonding. The strength of these interactions is found to be generally weak, similar to that of single-component energetic molecular crystals. By means of cocrystallization, the molecular stacking can be improved to be prone to layered stacking, facilitating low impact sensitivity. This could be feasible for alleviating the energy−safety contradiction of EMs. The driving force of the EMCC formation is thought to be the increase in entropy, because the EMCCs are in nature the products of an increase in randomness, with a small variation of intermolecular interactions in comparison with original pure components. Finally, the dependence of the properties of EMCCs on the compositions and molecular structures of original pure components is proposed to attract increasing attention, as it is a base for creating new EMs with tunable compositions, structures, and properties by way of crystal engineering.

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Section: Intermolecular Interactions In Emccsmentioning

confidence: 99%

Review of the Intermolecular Interactions in Energetic Molecular Cocrystals

Liu

Wei

Zhang

2020

Crystal Growth & Design

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“…In other words, it is a promising strategy for in-depth tuning of properties of EMs. In addition, it is found that the CL-20/MMI cocrystals with good detonation properties are extremely insensitive to impact and friction . Some CL-20-based cocrystals with high energy and low sensitivity can meet any requirements for high-energy components in the propellant formulations.…”

Section: Sensitivity Thermal Decomposition and Detonation Propertiesmentioning

confidence: 99%

“…Based on the types of EMs that were used to make cocrystals with nitramine explosives, it is found that and the major coformers include three types, which are nitramine, nitrobenzene, and nitrated azoles . Moreover, except for the CL-20-based cocrystals with energetic coformers, mostly CL-20/nonenergetic cocrystals (e.g., CL-20/MMI cocrystal, CL-20/2,4-MDNI cocrystal) have been prepared. The energetic cocrystals form a new structure, which may effectively improve the physicochemical properties, safety, and detonation performance, where in particular the sensitivity could be significantly reduced. − …”

Section: Introductionmentioning

confidence: 99%

Nitramine-Based Energetic Cocrystals with Improved Stability and Controlled Reactivity

Xue

Huang

et al. 2020

Crystal Growth & Design

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The inherent contradiction between the energy density and safety of energetic materials (EMs) is very challenging. To solve this problem, cocrystallization technology has been usually used in the field of EMs to better balance the energy and safety. The preparation techniques of energetic cocrystals mainly include solvent evaporation, solvent/nonsolvent, and grinding methods. The cocrystals prepared by these methods have structures completely different from the starting crystals. The comprehensive performance of energetic cocrystals (ECCs), such as density, solubility, sensitivity, and thermal stability, is significantly improved. This review summaries the preparation methods of ECCs and their fundamental formation mechanisms, where the HMX-based and CL-20-based ECCs are selected as typical examples. Their structures, sensitivity, thermodynamic characteristics, and detonation parameters are summarized and compared in detail. Finally, future research directions and challenges of ECCs are proposed based on this literature survey.

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“…Researchers have already prepared many CL‐20‐based cocrystals in solution . The above molecular conformers of CL‐20 have all been observed in CL‐20‐based cocrystals in ambient conditions; the γ ‐form and the β ‐form were the most common conformers of the reported CL‐20 cocrystals. As CL‐20 is a polymorphic molecule, the mechanism of its conformational transformation in solvents is quite complicated, and the influence of solvents still requires further study.…”

Section: Introductionmentioning

confidence: 98%

Exploring the effects of solvents on an organic explosive: Insights from the electron structure, electrostatic potential, and conformational transformations of 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane

Zhu

Gan

Cheng

et al. 2020

Int J of Quantum Chemistry

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In order to attain comprehensive insights into the crystallization of 2,4,6,8,10,4,6,8,10, from solutions, the geometric and electronic structures and conformational transformations of its β-, γ-, ε-, ζand ηforms in six organic solvents (ethanol, ethyl acetate, methanol, acetone, acetonitrile, and 2-propanol) were evaluated using quantum chemistry calculations. Results showed that solvents have little effect on the geometric structures of molecules but greatly impact the energy and electronic structure of CL-20. The electron density, atomic charges, and electrostatic potential of CL-20 exhibit polarization due to the solvent effect, especially in alcohols. The polarity of CL-20 increased because of the change in electron density. The transformations of the five conformers of CL-20 were studied thoroughly, and the energy barriers were evaluated using the Gibbs energies. Importantly, the reason η-CL-20 is only found in CL-20-based cocrystals was suggested. These results indicate that solvents play a critical role in crystal growth. K E Y W O R D SCL-20, conformational transformation, electron structure, organic explosive, solvent effect

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Syntheses, Crystal Structures, and Properties of Two Novel CL‐20‐based Cocrystals

Cited by 16 publications

References 39 publications

Review of the Intermolecular Interactions in Energetic Molecular Cocrystals

Review of the Intermolecular Interactions in Energetic Molecular Cocrystals

Nitramine-Based Energetic Cocrystals with Improved Stability and Controlled Reactivity

Exploring the effects of solvents on an organic explosive: Insights from the electron structure, electrostatic potential, and conformational transformations of 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane

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