Polymorphism of Energetic Materials: A Comprehensive Study of Molecular Conformers, Crystal Packing, and the Dominance of Their Energetics in Governing the Most Stable Polymorph

Crystal Growth & Design, Journal Year: 2018, Volume and Issue: 18(7), P. 4174 - 4186

Published: June 5, 2018

Polymorphism is universal in energetic crystals and brings much complexity revealing the underlying mechanism for materials against external stimuli. This work comprehensively studies molecular conformers (MCs), stacking, related MC energy (MCE) lattice (LE) of polymorphs six common (EMs), including 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX), 1,3,5-trinitro-1,3,5-triazinane (RDX), 2,2-dinitroethylene-1,1-diamine (FOX-7), 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN). We find dominance MCE or LE determining most stable polymorph at conditions variable; i.e., dominates CL-20, RDX, PETN, FOX-7, while governs HMX, two TNT below −150 °C, they have almost same stability without a difference either LE. The variability responsible current difficulty crystal structure predictions. Moreover, temperature elevation reduces volume (Vm) β-FOX PETN-II by weakening intermolecular interactions field effects to relax molecules be smaller ones. Besides, high pressure several GPa mainly shortens distances, rather than compresses Vm. Finally, heat-induced polymorphic transformation FOX-7 from α- β- γ-forms allows it more closely face-to-face π–π stacked serves as reason its low impact sensitivity. All these findings are expected deepen insight into response EMs

Language: Английский

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Packing Structures of CL-20-Based Cocrystals

Crystal Growth & Design, Journal Year: 2018, Volume and Issue: 18(11), P. 7065 - 7078

Published: Oct. 2, 2018

The CL-20-based cocrystals (CCCs) are now the most active in field of energetic cocrystals, due to an advantage high energy density while a disadvantage low stability CL-20, which may be tuned with desired structures and properties by cocrystallization. This work presents comprehensive insight into packing 27 CCCs observed since 2017. First, it shows multiplicity coformer molecules various shapes sizes. Regarding conformers, β-, γ-, η-, ε-, ζ-forms appear CCCs, total above that CL-20 polymorphs; two forms can exist same CCC highlights difference conformers between single component crystals cocrystals; γ- β-forms govern population 87%. conformational diversity serves as reason for abundance CCCs. Meanwhile, stoichiometric ratios from 1:1 1:6 except 1:5 observed, lower ones predominate populations 48 40% 1:2, respectively. Moreover, exhibits wavelike, sandwich, channel, caged molecular stacking Among these stacking, O···H, O···N, O···O contacts dominate weak intermolecular interactions, feature hydrogen bonding H atoms acyl/ether O molecules, p (of on NO2 CL-20)−π big π-bonds molecules) interactions. interactions contribute small volume variations after cocrystallization, maximum relative error ∼3%. Besides, each mediates those related pure components; no outperforms ε-CL-20 density. Finally, we find contents N facilitate increase coefficients densities. All findings expected enrich knowledge both materials enhance rationalization crystal design.

Language: Английский

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Polymorphic Transition in Traditional Energetic Materials: Influencing Factors and Effects on Structure, Property, and Performance

Crystal Growth & Design, Journal Year: 2020, Volume and Issue: 20(5), P. 3561 - 3576

Published: March 24, 2020

Polymorphism is universal in energetic materials, and polymorphic transformation (PT) causes variations the structure, properties, performance. This article reviews polymorphs of six traditional compounds (ECs), including 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), 1,3,5-trinitro-1,3,5-triazinane (RDX), 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX), 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), 2,2-dinitroethylene-1,1-diamine (FOX-7), PT-induced molecular packing structures energies, crystal morphology, sensitivity detonation performance, defects, as well factors influencing PT strategies for controlling PT. In all determined experimentally, there a small difference volume, whereas large can appear conformation, intermolecular distance, pattern, density, sensitivity, Moreover, addition to temperature pressure, quality additive seriously affect addition, recrystallization, coatings, additives are available control Finally, some issues raised, such determination new at high clarifying boundary mechanism, considering extremes understanding an EC, paying attention newly thriving cocrystals ionic salts.

Language: Английский

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Applying machine learning to balance performance and stability of high energy density materials

iScience, Journal Year: 2021, Volume and Issue: 24(3), P. 102240 - 102240

Published: Feb. 26, 2021

The long-standing performance-stability contradiction issue of high energy density materials (HEDMs) is extremely complex and multi-parameter nature. Herein, machine learning was employed to handle 28 feature descriptors 5 properties detonation stability 153 HEDMs, wherein all 21,648 data used were obtained through high-throughput crystal-level quantum mechanics calculations on supercomputers. Among five models, namely, extreme gradient boosting regression tree (XGBoost), adaptive boosting, random forest, multi-layer perceptron, kernel ridge regression, respectively trained evaluated by stratified sampling 5-fold cross-validation method. them, XGBoost model produced the best scoring metrics in predicting velocity, pressure, heat explosion, decomposition temperature, lattice predictions agreed with 1,383 experimental collected from massive literatures. Feature importance analysis conducted obtain data-driven insight into causality delivered optimal range key features for more efficient rational design advanced HEDMs.

Language: Английский

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Energetic Cocrystallization as the Most Significant Crystal Engineering Way to Create New Energetic Materials

Crystal Growth & Design, Journal Year: 2022, Volume and Issue: 22(2), P. 954 - 970

Published: Jan. 13, 2022

Crystal engineering is a highly efficient way to create new materials with the desired properties. Energetic cocrystallization has been thriving for ∼10 years since appearance of series TNT-based energetic cocrystals (ECCs). ECCs serve as one important aspect crystal (EMs). This article presents brief overview regarding component, intermolecular interaction, packing structure, main properties, and preparation, well theoretical treatment some issues raised future development. In most cases, properties an ECC are each moderated between those pure components, setting basis tuning by existing molecules, instead synthesizing molecules; meanwhile, there also exceptions, such higher density, detonation or lower impact sensitivity in comparison both components. These exceptions mutated will expand EMs. Generally, currently staying at primary stage, much effort being required solve urgent issues, property evaluation, large-scale fabrication, applications. Still, promising alternative EMs after all, it huge challenge synthesize satisfactory molecule.

Language: Английский

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1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB): Enlightening the way to create new Low-Sensitivity and High-Energy materials from a viewpoint of multiscale

Chemical Engineering Journal, Journal Year: 2024, Volume and Issue: 490, P. 151737 - 151737

Published: April 27, 2024

Language: Английский

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Insights into Structural and Energetic Features of 3,5-Dinitropyrazole-4-carboxylic Acid and Its Energetic Salts

Crystal Growth & Design, Journal Year: 2024, Volume and Issue: 24(16), P. 6790 - 6799

Published: July 31, 2024

The dominance of nitro pyrazole-based explosives in the recently reported high-performing energetic materials motivated us to comprehensively investigate energy–stability correlation among different compounds based on 3,5-dinitro pyrazoles employing various computational methods. We also explored and physicochemical properties overlooked compound 3,5-dinitropyrazole-4-carboxylic acid (CDNP). This study revealed that CDNP exhibits highest thermal stability 4-substituted-3,5-dinitropyrazoles, combined with an acceptable performance. These characteristics are attributed its layered packing, strong intermolecular interactions, carbonyl bonds. Furthermore, dicationic salt formation further allowed fine-tune overall performance stability. dihydroxylammonium (5) shows best performance, comparable well-known traditional explosive TATB, good low sensitivity toward impact friction.

Language: Английский

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Early Events When Heating 1,1-Diamino-2,2-dinitroethylene: Self-Consistent Charge Density-Functional Tight-Binding Molecular Dynamics Simulations

The Journal of Physical Chemistry C, Journal Year: 2018, Volume and Issue: 122(27), P. 15125 - 15132

Published: June 21, 2018

A self-consistent charge density-functional tight-binding method combined with molecular dynamics (MD) simulations and static density functional theory (DFT) calculations is employed to reveal the initial steps responsible for thermal decay of low sensitive high energetic material (EM) 1,1-diamino-2,2-dinitroethylene (FOX-7). Constant temperature heating temperature-programmed are accounted in our MD resemble practice. We find that style has an impact on decomposition mechanism FOX-7. The N–O bond rupture produce O radical observed first time simulation from 300 3000 K, together C–NO2 cleavage. also capture intra- intermolecular hydrogen transferred structures constant at this case, NO2 partition serves as another kind primary step thermally decaying FOX-7 too. Static DFT show transfers most energetically favored breaking a or requires energy above 60 kcal/mol. Still, scission bonds can dominate reactions because serious distortion reduces required enhanced entropy effect temperatures. These findings expected deepen insight into EMs.

Language: Английский

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Molecular-Shape-Dominated Crystal Packing Features of Energetic Materials

Crystal Growth & Design, Journal Year: 2021, Volume and Issue: 21(3), P. 1540 - 1547

Published: Feb. 16, 2021

Molecular shape is observed to greatly determine the properties of energetic materials (EMs); that is, spherical molecules generally have high energy while planar low sensitivity in common. Nevertheless, how molecular shapes along with their packing modes affect crystal features, such as density and coefficient (PC), are crucial factors describing EMs, still unclear. Herein, this issue was addressed via a statistical analysis more than 103 available crystals. Despite having an overall increasing trend PC, PC dominated by molecules, respectively. Intra- intermolecular hydrogen bonds important features Hopefully, results reported here can deepen understanding structure–property relationship rationally design novel EMs outstanding properties. Moreover, present study provides route quantitatively identify based on simple structural parameters, which be further applied detailed identification crystals specific modes.

Language: Английский

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A review of quantum chemical methods for treating energetic molecules

Energetic Materials Frontiers, Journal Year: 2021, Volume and Issue: 2(4), P. 292 - 305

Published: Nov. 30, 2021

As a necessary tool for understanding, prediction, and design (especially on microscopic scale), Quantum chemical (QC) methods have profound impact the field of energetic materials (EMs). This study focuses upon QC applicable to molecules their related applications. They generally include Hartree-Fock method, semi-empirical methods, density functional theory (DFT), high-accuracy ab initio methods. includes detailed discussion about application scope accuracy descriptions geometric structure, electronic thermodynamic property, reactivity molecules. Additionally, this stresses machine learning combined with DFT calculations that becomes increasingly popular as an important way establish models accurate property predictions. work is expected be instructive constructive use in EM study.

Language: Английский

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