γ‐FOX‐7: Structure of a High Energy Density Material Immediately Prior to Decomposition

Crawford, Margaret-Jane; Evers, Jürgen; Göbel, Michael; Klapötke, Thomas M.; Mayer, Péter; Oehlinger, Gilbert; Welch, Jan M.

doi:10.1002/prep.200700240

Cited by 110 publications

(101 citation statements)

References 15 publications

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“…1) by Mittapalli et al, reported in this issue of IUCrJ, revealed four polymorphs, three of which exhibit mechanical responses such as jumping (forms I and III) and exploding (form II) during phase transition at high temperature (Mittapalli et al, 2017). This is a rare example of a combination of mechanophysical responses in polymorphs of the same compound (Steiner et al, 1993;Crawford et al, 2007;Sahoo et al, 2013). The crystal structures showed that the N-salicylideneaniline molecules interact via amide N-HÁ Á ÁO dimersynthon and C-ClÁ Á ÁO halogen-bond motifs in all polymorphic modifications.…”

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confidence: 87%

Regulating thermosalient behaviour in three polymorphs

Werny

Vittal

2017

Int Union Crystallogr J

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Dynamic molecular crystals can be defined as crystalline materials that respond to external stimuli with mechanical responses on a macro-, micro-or nanoscopic scale (Naumov et al., 2015). The motility of dynamic crystals is usually triggered by a phase transition or chemical reaction without gaseous products, subsequently creating local stresses in the densely packed crystal lattice of the respective material (Commins et al., 2016). The amplification of such strain via cooperative processes can lead to reversible or irreversible phase deformation, instantaneous propulsion and even disintegration. Crystalline materials, which are classically defined as rigid and brittle entities, thus display a reversible mechanical response in the form of shape change (curling, bending, twisting) or locomotion (jumping, flipping, rotation, etc.) (Nath et al., 2014). A class of dynamic single crystals, known as thermosalient crystals, can propel themselves over distances hundreds of times larger than their own size when they are exposed to heat. The earliest known thermosalient crystal, (phenylazophenyl)palladium hexafluoroacetylacetone, was reported more than 30 years ago (Etter & Siedle, 1983). Only in recent years, however, have researchers begun to fully investigate thermosalient phase transitions on a structural, kinematic and mechanistic basis. The observed conversion of heat energy into mechanical motion by a densely packed crystal lattice represents a phenomenon that could be integrated into a host of new applications, e.g. actuators, sensors and pressure-sensitive applications (Commins et al., 2016). In general, a limited yet distinct anisotropic expansion of the crystal unit cell is accompanied by the nucleation and propagation of a new phase within the bulk crystal (phase transition) (Nath et al., 2014). The resulting build-up of strain at the phase interface, if larger than the cohesive interactions present within the crystal lattice, instigates a mechanical force (self-actuation). Phenomena such as molecular dimerization, intermolecular charge transfer and intermolecular proton transfer depend on the way the molecules are assembled in a crystal. Similarly, the dynamic properties of crystals, which occur in response to external stimuli, are also controlled by the intermolecular interactions. Theinteractions, hydrogen bonds, halogen bonds and coordination bonds contribute decisively to the cooperative behaviour of the dynamic switching process. In the case of thermoresponsive materials, the dissipation of thermal energy is influenced by the crystal packing (Naumov et al., 2015). The study of a dichloro derivative of N-salicylideneaniline (see Fig. 1) by Mittapalli et al., reported in this issue of IUCrJ, revealed four polymorphs, three of which exhibit mechanical responses such as jumping (forms I and III) and exploding (form II) during phase transition at high temperature (Mittapalli et al., 2017). This is a rare example of a combination of mechanophysical responses in polymorphs of the same compound (Steiner et al., 1...

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confidence: 87%

Regulating thermosalient behaviour in three polymorphs

Werny

Vittal

2017

Int Union Crystallogr J

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“…The distance between layers is ~ 3 Å. The results of more detailed studies of the crystal structure of α-, β-and γ-FOX-7 by X-ray single crystal and powder investigations are reported in [29] and [30].…”

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confidence: 99%

1,1-Diamino-2,2-dinitroethene (DADNE, FOX-7) – Properties and Formulations (a Review)

Trzciński

Belaada

2016

Cent. Eur. J. Energ. Mater.

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A review of the available literature on the properties of 1,1-diamino-2,2-dinitroethene (DADNE, FOX-7) and formulations containing FOX-7 is presented in this paper. The structural, thermal and spectroscopic properties as well as the sensitivity and explosive properties of FOX-7 are described. Compositions containing FOX-7 are characterized in details and their sensitivity and explosive properties are presented. Potential areas of application for such formulations have been identified.

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“…The calculated lattice parameters are shown in Table 1 together with their experimental values. 4,5 It is found that the errors in the LDA (CA-PZ) results are smaller than those in the GGA (PW91) results in comparison with the experimental values for α-, β-, and γ-phase. This indicates that the accuracy of the LDA function is better than that of the GGA.…”

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confidence: 90%

“…Only slight changes in both crystal axes and positional parameters are required to transform from the monoclinic α-phase. The crystal structure of the γ-phase has been determined by Crawford et al 5 γ-FOX-7 consists of four planar layers, each containing two crystallographically independent molecules, and the waveshaped layers of FOX-7 molecules formed in head-to-tail arrangements in α-and β-FOX-7 are flattened in γ-FOX-7 forming planar layers.…”

Section: -5mentioning

confidence: 99%

First-Principles Study of the Three Polymorphs of Crystalline 1,1-Diamino-2,2-dinitrotheylene

Wu¹,

Zhu²,

Xiao³

2013

Bulletin of the Korean Chemical Society

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The electronic structure, optical spectra, and thermodynamic properties of the three FOX-7 polymorphs (α, β, and γ) have been studied systematically using density functional theory. The LDA (CA-PZ) and generalized gradient approximation (GGA) (PW91) functions were used to relax the three FOX-7 phases without any constraint. Their density of states and partial density of states were calculated and analyzed. The band gaps for the three phases were calculated and the sequence of their sensitivity was presented. Their absorption coefficients were computed and compared. The thermodynamic functions including enthalpy (H), entropy (S), free energy (G), and heat capacity (C p ) for the three phases were evaluated.

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γ‐FOX‐7: Structure of a High Energy Density Material Immediately Prior to Decomposition

Cited by 110 publications

References 15 publications

Regulating thermosalient behaviour in three polymorphs

Regulating thermosalient behaviour in three polymorphs

1,1-Diamino-2,2-dinitroethene (DADNE, FOX-7) – Properties and Formulations (a Review)

First-Principles Study of the Three Polymorphs of Crystalline 1,1-Diamino-2,2-dinitrotheylene

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