Thermal stability of azole-rich energetic compounds: their structure, density, enthalpy of formation and energetic properties

Physical Chemistry Chemical Physics, Journal Year: 2023, Volume and Issue: 25(28), P. 18523 - 18544

Published: Jan. 1, 2023

Increasing the strength and number of hydrogen bonds azoles expanding π–π stacking area are key factors to improve thermal stability, which provides a valuable way for developing energetic materials with higher energy stability.

Language: Английский

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Collective Variables for Conformational Polymorphism in Molecular Crystals

The Journal of Physical Chemistry Letters, Journal Year: 2023, Volume and Issue: 14(4), P. 971 - 976

Published: Jan. 23, 2023

Controlling polymorphism in molecular crystals is crucial the pharmaceutical, dye, and pesticide industries. However, its theoretical description extremely challenging, due to associated long timescales ($ > 1 \, \mu s$). We present an efficient procedure for identifying collective variables that promote transitions between conformational polymorphs dynamics simulations. It involves applying a simple dimensionality reduction algorithm data from short ($\sim ps$) simulations of isolated conformers correspond each polymorph. demonstrate utility our method challenging case important energetic material, CL-20, which has three anhydrous at ambient pressure. Using these Metadynamics simulations, we observe all solid biased trajectories. reconstruct free energy surface identify previously unknown defect intermediate forms transition one known polymorph another. Our provides insights into complex polymorphic flexible crystals.

Language: Английский

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Unfolding the chemistry of FOX-7: Unique energetic material and precursor with numerous possibilities

Chemical Engineering Journal, Journal Year: 2021, Volume and Issue: 431, P. 133378 - 133378

Published: Nov. 6, 2021

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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n−π Stacking in Energetic Crystals

Crystal Growth & Design, Journal Year: 2022, Volume and Issue: 22(3), P. 1991 - 2000

Published: Feb. 18, 2022

n−π stacking refers to the molecular through lone-pair electron (n)-π-structure interaction. As an important mode supplementary hydrogen bonding (HB) and π–π stacking, which are usually dominant in intermolecular interaction, it has generally been ignored energetic crystals. This work extracts typical stacked single-component crystals cocrystals from CSD categorizes them into three forms, including contacts of NO2 benzene ring, heterocycle, furazan ring–furazan ring. The nature weak electrostatic attraction because each couple always possesses a weakly positively charged π negatively n. ranges 6.3 20.0 kJ/mol energy is weaker than HB stacking. exhibits T-shape can hardly occur alone for planar molecules with strong acceptors donors. Hopefully, this expected enrich perfect knowledge interactions pave way comprehensive understanding therein.

Language: Английский

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Color Packing Polymorphism in an Organic Chromophore

Crystal Growth & Design, Journal Year: 2024, Volume and Issue: 24(2), P. 646 - 656

Published: Jan. 2, 2024

Optical materials represent a class of exotic in optics, lenses, lasers, optic fiber communication, and optical storage devices, etc. Organic are excellent alternatives to conventional inorganic because their flexibility, low costs, environmentally friendly nature, Here, we report color trimorphism (three polymorphic forms: orange, light-orange, yellow, abbreviated as OLY) an organic chromophore via systematic physicochemical characterizations. We focused on N,N-dimethyl bromo substituted thienyl chalcone─a push–pull chromophore. performed characterizations using UV–vis, solid-state photoluminescence, powder single-crystal X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, hot-stage microscopy highlight the similarities differences OLY forms title compound. also calculated lattice interaction energies compared them understand energetic stabilities polymorphs. Further, based electron densities for selected dimers extracted from crystal structure, quantified intermolecular interactions highlighted density distributions across three The detailed analysis structures suggests that this is case packing polymorphism. colors these polymorphs correlate well with results obtained spectroscopic computational studies.

Language: Английский

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Review of Phase Transformations in Energetic Materials as a Function of Pressure and Temperature

The Journal of Physical Chemistry C, Journal Year: 2019, Volume and Issue: 123(48), P. 29067 - 29085

Published: Oct. 14, 2019

Under ambient conditions, energetic materials may exist in one or more than metastable crystal structure. compression when heated, the material transform into a different structure decompose. Mapping phase diagram of explosive at high pressures and temperatures is an important component to evaluate their performance safety aspects. In particular, detailed knowledge polymorphism structural chemical stabilities various phases necessary understand reactive behavior high-pressure high-temperature range that relevant shock-wave initiation. Phase transformations could be rate-dependent; is, fast rapid heating result transformation pressures, temperatures, even structures compared with static slow because shock accompanied by sudden extreme effects. Nevertheless, methods are expected give fair idea under P–T conditions and, from structure, characteristics. Also, physics chemistry explosives so complex experiments it has not been possible identify intermediate molecules during decomposition. Hence pressure temperature gain insight these processes. Additionally, computational modeling simulations have extensively used effects on explosives. There considerable literature aspects accumulated over years. We will review current status experimental results, primarily using X-ray diffraction, Raman, infrared spectroscopies, as probes exploring secondary ammonium nitrate, TNT, TATB, PETN, RDX, HMX, CL-20, TEX, FOX-7, TKX-50.

Language: Английский

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Difference in the Thermal Stability of Polymorphic Organic Crystals: A Comparative Study of the Early Events of the Thermal Decay of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) Polymorphs under the Volume Constraint Condition

The Journal of Physical Chemistry C, Journal Year: 2019, Volume and Issue: 123(27), P. 16565 - 16576

Published: June 19, 2019

Polymorphism is universal in organic crystals like conventional energetic materials (EMs), and it may cause a difference thermal stability, one of the most important properties EMs. Nevertheless, deep insights into differences polymorphic EMs are lacking. 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) powerful EM commercialized already possesses three polymorphs stabilized at common condition, which exhibit many performances. However, underlying mechanism responsible for these remains unclear. In this work, self-consistent charge density functional tight binding scheme molecular dynamics simulations combined to reveal decay CL-20, with considerations an extreme volume constraint two heating types. The lower activity ε-CL-20 distinguished from β- γ-CL-20 relatively low temperature 1000 K, as only does not decompose time scale simulation 20 ps. partly its impact sensitivity. Two high temperatures 1500 2000 K cannot differentiate their activities. Moreover, unimolecular N–N breakage governs first steps all polymorphs. Five types bond cleavages, including NO2 partitions 5- 6-membered rings, cleavage C–N bonds C–C breakage, observed decay. Interestingly, five ignitions be any case. Besides, we find that disfavors formation stable products N2 CO2. These results expected give complicated sensitivity

Language: Английский

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Polymorphism in a Nonsensitive-High-Energy Material: Discovery of a New Polymorph and Crystal Structure of 4,4′,5,5′-Tetranitro-1H,1′H-[2,2′-biimidazole]-1,1′-diamine

Crystal Growth & Design, Journal Year: 2020, Volume and Issue: 20(12), P. 8005 - 8014

Published: Oct. 28, 2020

Polymorphism has attracted significant attention in the area of pharmaceutical chemistry and materials chemistry. For energetic materials, polymorphism may affect their physical performances such as energy, sensitivity, thermal stability, etc. 4,4′,5,5′-Tetranitro-1H,1′H-[2,2′-biimidazole]-1,1′-diamine (DATNBI) exhibits high density (d: 1.93 g cm–3), superior detonation performance (D: 9063 m s–1) comprehensive sensitivity (IS: 15 J), suggesting it is a nonsensitive-high-energy material (NSHEM) compared with HMX sensitive-high-energy (SHEM). In this work, new polymorph DATNBI was discovered for first time. To elucidate its phase transformation behavior morphology-performance relationship, single X-ray diffraction (SXRD), variable temperature powder (VT-PXRD), Raman spectroscopy, differential scanning calorimetry-thermal gravity (DSC-TG), electron microscopy (SEM) were characterized thoroughly. Solvation effects on formation also investigated.

Language: Английский

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Molecular Packing Density Coefficient Contradiction of High-Density Energetic Compounds and a Strategy to Achieve High Packing Density

Crystal Growth & Design, Journal Year: 2022, Volume and Issue: 22(5), P. 3252 - 3263

Published: April 21, 2022

High packing density (dc) is of great importance in the field energetic materials, as it positively correlated with energy performances, which refer to power, detonation property, or specific kinetic a cylinder. This makes high dc focus for designing new molecules. article systematically analyzes composition, molecular topology, intermolecular interaction, molecule (dm), and coefficient (PC) top 36 highest (≥1.90 g/cm3) CHNO compounds extracted from CSD. For these compounds, dm–PC contradiction exists. dm increases, PC decreases. The absence planar structure strong hydrogen bonding acceptor donor high-dm molecules responsible low contradiction. Two strategies are summarized achieving dc: first, design caged oxygen balance because they generally possess extraordinarily remedy shortcoming rather PC, other dense acceptors donors obtain PCs further based on moderate dm. introduction NH2 needs be emphasized second strategy. work expected guide high-density compounds.

Language: Английский

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