scholarly journals Towards Computational Screening for New Energetic Molecules: Calculation of Heat of Formation and Determination of Bond Strengths by Local Mode Analysis

2021 ◽  
Vol 9 ◽  
Author(s):  
Imogen L. Christopher ◽  
Adam A. L. Michalchuk ◽  
Colin R. Pulham ◽  
Carole A. Morrison
Keyword(s):  
Solid State ◽  
Gas Phase ◽  
Energetic Materials ◽  
Inorganic Compounds ◽  
Heats Of Formation ◽  
Mode Analysis ◽  
Local Mode ◽  
Reliable Determination ◽  
Computational Screening

The reliable determination of gas-phase and solid-state heats of formation are important considerations in energetic materials research. Herein, the ability of PM7 to calculate the gas-phase heats of formation for CNHO-only and inorganic compounds has been critically evaluated, and for the former, comparisons drawn with isodesmic equations and atom equivalence methods. Routes to obtain solid-state heats of formation for a range of single-component molecular solids, salts, and co-crystals were also evaluated. Finally, local vibrational mode analysis has been used to calculate bond length/force constant curves for seven different chemical bonds occurring in CHNO-containing molecules, which allow for rapid identification of the weakest bond, opening up great potential to rationalise decomposition pathways. Both metrics are important tools in rationalising the design of new energetic materials through computational screening processes.

Computational Determination of Heats of Formation of Energetic Compounds

1995 ◽  
Vol 418 ◽  
Author(s):  
Peter Politzer ◽  
Jane S. Murray ◽  
M. Edward Grice
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Functional Group ◽  
Solid Phase ◽  
Heats Of Formation ◽  
Energetic Compounds ◽  
Phase Data ◽  
Heats Of Vaporization ◽  
Group Effects

AbstractA recently-developed density functional procedure for computing gas phase heats of formation is briefly described and results for several categories of energetic compounds are summarized and discussed. Liquid and solid phase values can be obtained by combining the gas phase data with heats of vaporization and sublimation estimated by means of other relationships. Some observed functional group effects upon heats of formation are noted.

scholarly journals Vibrational Analysis of Benziodoxoles and Benziodazolotetrazoles

Physchem ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 45-68
Author(s):  
Seth Yannacone ◽  
Kapil Dev Sayala ◽  
Marek Freindorf ◽  
Nicolay V. Tsarevsky ◽  
Elfi Kraka
Keyword(s):  
Energetic Materials ◽  
Substituent Effects ◽  
Vibrational Analysis ◽  
Mode Analysis ◽  
Hypervalent Iodine ◽  
Local Mode ◽  
Explosive Decomposition ◽  
Local Vibrational Mode ◽  
Bond Strengths ◽  
The Stability

Tetrazoles are well known for their high positive enthalpy of formation which makes them attractive as propellants, explosives, and energetic materials. As a step towards a deeper understanding of the stability of benziodazolotetrazole (BIAT)-based materials compared to their benziodoxole (BIO) counterparts, we investigated in this work electronic structure features and bonding properties of two monovalent iodine precursors: 2-iodobenzoic acid and 5-(2-iodophenyl)tetrazole and eight hypervalent iodine (III) compounds: I-hydroxybenzidoxolone, I-methoxybenziodoxolone, I-ethoxybenziodoxolone, I-iso-propoxybenziodoxolone and the corresponding I-hydroxyben ziodazolotetrazole, I-methoxybenziodazolotetrazole, I-ethoxybenziodazolotetrazole and I-iso- propoxybenziodazolotetrazole. As an efficient tool for the interpretation of the experimental IR spectra and for the quantitative assessment of the I−C, I−N, and I−O bond strengths in these compounds reflecting substituent effects, we used the local vibrational mode analysis, originally introduced by Konkoli and Cremer, complemented by electron density and natural bond orbital analyses. Based on the hypothesis that stronger bonds correlate with increased stability, we predict that, for both series, i.e., substituted benziodoxoles and benziodazolotetrazoles, the stability increases as follows: I-iso-propoxy < I-ethoxy < I-methoxy < I-hydroxy. In particular, the I−N bonds in the benziodazolotetrazoles could be identified as the so-called trigger bonds being responsible for the initiation of explosive decomposition in benziodazolotetrazoles. The new insight gained by this work will allow for the design of new benziodazolotetrazole materials with controlled performance or stability based on the modulation of the iodine bonds with its three ligands. The local mode analysis can serve as an effective tool to monitor the bond strengths, in particular to identify potential trigger bonds. We hope that this article will foster future collaboration between the experimental and computational community being engaged in vibrational spectroscopy.

Synthesis and Crystal Structure Determination of (R,S)-Diphenyl 1-CyclohexyI-1-(4-nitroanilino)methanephosphonate

1997 ◽  
Vol 52 (12) ◽  
pp. 1544-1548
Author(s):  
Adel Amer ◽  
Ho Hans ◽  
Hans Zimmer
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Solid State ◽  
Gas Phase ◽  
Structure Determination ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Fab Mass Spectrometry ◽  
Long Time

Though diphenyl 1,1-diarylsubstituted phosphonates are known for a long time, FAB-mass spectrometry and X-ray crystal analysis revealed that these species occur as dimers in the solid state and in the gas phase.

Prediction of the Strength of Energetic Materials Using the Condensed and Gas Phase Heats of Formation

2014 ◽  
Vol 40 (4) ◽  
pp. 551-557 ◽  
Author(s):  
Mohammad Kamalvand ◽  
Mohammad Hossein Keshavarz ◽  
Mohammad Jafari
Keyword(s):  
Gas Phase ◽  
Energetic Materials ◽  
Heats Of Formation

Structure, Thermochemistry and Reactivity of Protonated Glycolaldehyde

2001 ◽  
Vol 7 (4-5) ◽  
pp. 351-357 ◽  
Author(s):  
Guy Bouchoux ◽  
Florence Penaud-Berruyer ◽  
William Bertrand
Keyword(s):  
Gas Phase ◽  
Kinetic Method ◽  
Critical Energy ◽  
Protonated Form ◽  
Heats Of Formation ◽  
Molecular Orbital Calculations ◽  
Perfect Agreement ◽  
Stable Conformation ◽  
Water Complex

Structures and relative energies of various conformers of the simplest sugar, glycolaldehyde, 1, and its protonated form, [1H]+, were investigated by ab initio molecular orbital calculations. The 298 K heats of formation of the most stable conformers, deduced from the atomization energies at the G2 level, are equal to Δ fH°(1) = −324.8 kJ mol−1 and Δ fH°[1H]+ = 426.0 kJ mol−1. The corresponding proton affinity value is PA(1) = 779.8 kJ mol−1, in perfect agreement with the experimental determination of 783.3 ± 3.8 kJ mol−1 obtained by the kinetic method. A gas-phase basicity value, GB(1), of 745–748 kJ mol−1 is also deduced from theory and experiment. The exclusive dissociation channel of protonated glycolaldehyde, [1H]+, is water loss which leads essentially to the acylium ion [CH3CO]+. The corresponding potential energy profile, investigated at the MP2/6–31G* level, reveals a route via a [CH3CO]+ / water complex after an energy determining step involving a simultaneous 1,2-hydrogen migration and C–O bond elongation. The critical energy of the reaction, evaluated at the G2(MP2,SVP)level, is 170 kJ mol −1 above the most stable conformation of the [1H]+ ion. The 298 K heats of formation of the three most stable [C2H3O]+ ions have been calculated at the G2 level: Δ fH°[CH3CO]+ = 655.0 kJ mol−1, Δ fH°[CH2COH]+ = 833.0 kJ mol−1, Δ fH°[c-CH2CHO]+ = 886.2 kJ mol−1.

A panel of mono- and dinucleotide microsatellite markers is required for reliable determination of the MSI status in colorectal cancer

2001 ◽  
Vol 120 (5) ◽  
pp. A599-A599
Author(s):  
C ARNOLD ◽  
A GOEL ◽  
J CARETHERS ◽  
L WASSERMAN ◽  
C COMPTON ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Microsatellite Markers ◽  
Reliable Determination
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