Electroactive Explosives: Nitrate Ester‐Functionalized 1,2,4,5‐Tetrazines

Chávez, David E.; Hanson, Susan K.; Veauthier, Jacqueline M.; Parrish, Damon A.

doi:10.1002/ange.201302128

Cited by 33 publications

(18 citation statements)

References 23 publications

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“…30−34 This lack of a systematic theoretical analysis is in sharp contrast with the need for understanding the electronic structure for many technological and medical applications. Interest in nitro-esters is growing due to recently synthesized nitrate ester-functionalized electroactive tetrazines, 35 which promise to be capable of on/off fluorescence switching through reversible oxidation/reduction chemistry.…”

Section: Introductionmentioning

confidence: 99%

Energies of Electronic Transitions of Pentaerythritol Tetranitrate Molecules and Crystals

2014

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Despite significant effort in research on energetic nitrocompounds coupled with a great interest in these materials for a range of technological and medical applications, the electronic structure of condensed energetic materials is barely studied. In this research aimed at a better understanding of the low energy absorption in the optical spectrum of nitro-compounds, the electronic structure and vertical electronic transitions of a gas-phase pentaerythritol tetranitrate (PETN) molecule and an ideal PETN crystal were explored by means of density functional theory based calculations. In accordance with most experimental observations, the optical absorption spectrum of PETN has a well-resolved intense band above 6 eV that is accompanied by a few low intensity broad bands at lower energies. Our modeling suggests that the high intensity band corresponds to a series of strong singlet−singlet transitions, while the lower energy bands are attributed to the formation of tightly bound singlet and triplet excitons. All transitions are well-localized on O−NO 2 groups of PETN. We also systematically analyze low energy excitations in other nitro-compounds, which exhibit similar patterns in the spectra even though the experimental data are incomplete at the moment. We predict that tightly bound excitons and charge transfer excitons should exist in PETN and both would trigger the nitrate decomposition, which allows for precise control of the initiation process.

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Section: Introductionmentioning

confidence: 99%

Energies of Electronic Transitions of Pentaerythritol Tetranitrate Molecules and Crystals

2014

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“…Explosophores such as nitro (NO 2 ) and azide (N 3 ) functional groups are generally needed to sensitize energetic materials. X‐NO 2 (X = N,C,O) bonds substituted on energetic materials have been proposed to form “trigger bonds,” activated (i.e., more readily cleaved) bonds that break to initiate an explosive reaction .…”

Section: Introductionmentioning

confidence: 99%

“…[7] Thus, much effort to understand decomposition has relied upon information from molecular dynamics and density functional theory (DFT) to predict performance and sensitivity from measures of bond strength and mechanisms. [2,7,8] Explosophores [9] such as nitro (ANO 2 ) [10][11][12][13][14] and azide (AN 3 ) [15] functional groups are generally needed to sensitize energetic materials. X-NO 2 (X 5 N,C,O) bonds substituted on energetic materials have been proposed to form "trigger bonds," activated (i.e., more readily cleaved) bonds that break to initiate an explosive reaction.…”

Section: Introductionmentioning

confidence: 99%

Trigger bond analysis of nitroaromatic energetic materials using wiberg bond indices

Shoaf

Bayse

2018

J Comput Chem

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The identification of trigger bonds, bonds that break to initiate explosive decomposition, using computational methods could help direct the development of novel, "green" and efficient high energy density materials (HEDMs). Comparing bond densities in energetic materials to reference molecules using Wiberg bond indices (WBIs) provides a relative scale for bond activation (%ΔWBIs) to assign trigger bonds in a set of 63 nitroaromatic conventional energetic molecules. Intramolecular hydrogen bonding interactions enhance contributions of resonance structures that strengthen, or deactivate, the CNO trigger bonds and reduce the sensitivity of nitroaniline-based HEDMs. In contrast, unidirectional hydrogen bonding in nitrophenols strengthens the bond to the hydrogen bond acceptor, but the phenol lone pairs repel and activate an adjacent nitro group. Steric effects, electron withdrawing groups and greater nitro dihedral angles also activate the CNO trigger bonds. %ΔWBIs indicate that nitro groups within an energetic molecule are not all necessarily equally activated to contribute to initiation. %ΔWBIs generally correlate well with impact sensitivity, especially for HEDMs with intramolecular hydrogen bonding, and are a better measure of trigger bond strength than bond dissociation energies (BDEs). However, the method is less effective for HEDMs with significant secondary effects in the solid state. Assignment of trigger bonds using %ΔWBIs could contribute to understanding the effect of intramolecular interactions on energetic properties. © 2018 Wiley Periodicals, Inc.

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“…The use of WBIs to characterize trigger bonds could be applied to explain the variable explosive properties of novel nitrogen‐rich energetic materials based on nitro (−NO 2 ), nitramine ( − NNO 2 ), and nitrate ester (−ONO 2 ) functional groups. For example, Fischer et al .…”

Section: Introductionmentioning

confidence: 99%

Predicting Trigger Bonds in Explosive Materials through Wiberg Bond Index Analysis

2015

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Understanding the explosive decomposition pathways of high-energy-density materials (HEDMs) is important for developing compounds with improved properties. Rapid reaction rates make the detonation mechanisms of HEDMs difficult to understand, so computational tools are used to predict trigger bonds-weak bonds that break, leading to detonation. Wiberg bond indices (WBIs) have been used to compare bond densities in HEDMs to reference molecules to provide a relative scale for the bond strength to predict the activated bonds most likely to break to trigger an explosion. This analysis confirms that X-NO2 (X=N,C,O) bonds are trigger linkages in common HEDMs such as TNT, RDX and PETN, consistent with previous experimental and theoretical studies. Calculations on a small test set of substituted tetrazoles show that the assignment of the trigger bond depends upon the functionality of the material and that the relative weakening of the bond correlates with experimental impact sensitivities.

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Electroactive Explosives: Nitrate Ester‐Functionalized 1,2,4,5‐Tetrazines

Cited by 33 publications

References 23 publications

Energies of Electronic Transitions of Pentaerythritol Tetranitrate Molecules and Crystals

Energies of Electronic Transitions of Pentaerythritol Tetranitrate Molecules and Crystals

Trigger bond analysis of nitroaromatic energetic materials using wiberg bond indices

Predicting Trigger Bonds in Explosive Materials through Wiberg Bond Index Analysis

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