Theoretical investigation on the structures,densities, and detonation properties of polynitrotetraazaoctahydroanthracenes

The polynitrotetraazaoctahydroanthracenes were optimized to obtain their molecular geometries and electronic structures at density functional theory–B3LYP/6‐31+G(d) level. Detonation velocities (D) and detonation pressures (P) were estimated for this nitramine compounds using Kamlet‐Jacobs equations, based on the theoretical densities (ρ) and heats of formation. It is found that there are good linear relationships between volume, density, detonation velocity, detonation pressure and the number of nitro group. Thermal stability of the compounds was investigated by calculating the bond dissociation energies and energy gap (ΔE_LUMO–HOMO). The simulation results reveal that molecule H performs similarly to famous explosive RDX. These results provide basic information for molecular design of novel high energetic density compounds. © 2011 Wiley Periodicals, Inc.     

Effects of Epoxidation and Nitration on Ballistic Properties of FOX‐7 – A DFT Study

1, 1‐Diamino‐2, 2‐dinitroethylene (FOX‐7) has received increasing attention since it was industrialized in the late 1990s. It has lower sensitivity and comparable performance to RDX. This paper presents ballistic properties of FOX‐7, its mono and dinitro derivatives and their epoxide derivatives computationally. The structures were optimized at the B3LYP/6‐31G(d, p) level and the bond lengths were calculated. The calculated data for FOX‐7 are compatible with the literature one. We have investigated the bond dissociation energies of the molecules. Mulliken electro negativities (χ_M) and chemical hardness (η) were reviewed using Frontier Molecular Orbitals at HF/6‐31G(d, p)//B3LYP/6‐31G(d, p) theoretical level. The detonation performance analyses were done using empirical Kamlet‐Jacobs equations. Additionally, power index values were calculated. All the compounds considered in the present article are powerful candidates for high energy materials.     

Theoretical investigation of an energetic fullerene derivative

A self‐consistent estimation method for the thermochemical properties of N‐methyl‐3‐(2′,4′,6′‐trinitrobenzene)‐fulleropyrrolidine (MTNBFP) is presented. This method is based on enthalpy of formation (Δ_fH) and enthalpy of combustion obtained from BLYP/DNP calculations of the total energies and frequencies for MTNBFP. The enthalpy of formation was calculated by an optimized set of isodesmic reactions given the available experimental Δ_fH of relative compounds. MTNBFP has a high enthalpy of formation, 2782.2 kJ/mol. Detonation velocity and detonation pressure were also presented in terms of Kamlet and Jacobs equations. Drop hammer impact sensitivity tests and blasting point per 5 s tests indicate MTNBFP may be a potential candidate primary explosive. To understand the test results well, we proposed a series of chemical reaction mechanisms and interpreted the relationship between impact sensitivity and electronic structures from the viewpoint of nitro group charge, electrostatic potential, and vibrational modes. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010     

Theoretical Study on the High Energy Density Compound Hexanitrohexaazatricyclotetradecanedifuroxan

Density functional theory （DFT） has been employed to study the molecular geometries, electronic structures, infrared （IR） spectra, and thermodynamic properties of the high energy density compound hexanitrohexaazatricyclotetradecanedifuroxan （HHTTD） at the B3LYP/6-31G^＊＊ level of theory. The calculated results show that there are four conformational isomers （α, β, γ and δ） for HHTTD, and the relative stabilities of four conformers were assessed based on the calculated total energies and the energy-gaps between the frontier molecular orbitals. The computed harmonic vibrational frequencies are in reasonable agreement with the available experimental data. Thermodynamic properties derived from the IR spectra on the basis of statistical thermodynamic principles are linearly correlated with the temperature. Detonation performances were evaluated by using the Kamlet-Jacobs equations based on the calculated densities and heats of formation. It was found that four HHTTD isomers with the predicted densities of ca. 2 g·cm^-3, detonation velocities near 10 km·s^-1, and detonation pressures over 45 GPa, may be novel potential candidates of high energy density materials （HEDM）. These results may provide basic information for the molecular design of HEDM.     

Molecular Structure and a Density Functional Theoretical Study on 2‐Nitroimino‐5‐Nitro‐Hexahydro‐1,3,5‐Triazine (NNHT)

2‐Nitroimino‐5‐nitro‐hexahydro‐1,3,5‐triazine (NNHT), was synthesized and its structure was determined by single‐crystal X‐ray diffraction. The crystal is monoclinic, space group P2₁/c with crystal parameters of a = 9.4031(13) Å, b = 8.5891(12) Å, c = 9.0200(13) Å, β = 91.213(2)°, V = 728.33(18) ų, Z = 4, F(000) = 392, D_c = 1.734 g/cm³. The experimental geometry of NNHT was input to Gaussian‐03W program and optimized using DFT‐B3LYP/6‐311++G** method. The IR frequencies and NMR chemical shift were carried out and compared well with those of the experimental. The atomic net charges and the population analysis are discussed. The heat of formation (HOF) for NNHT was evaluated by designing an isodesmic reaction. The detonation velocity (D) and detonation pressure (P) were estimated by using the well known Kamlet‐Jacobs equation, based on the theoretical HOF.     

DFT Studies on Detonation Properties,Pyrolysis Mechanism,and Stability of the Nitro and Hydroxyl Derivatives of Benzene

Ninety‐one nitro and hydroxyl derivatives of benzene were studied at the B3LYP/6‐31G?? level of density functional theory. Detonation properties were calculated using the Kamlet‐Jacobs equation. Three candidates (pentanitrophenol, pentanitrobenzene, and hexanitrobenzene) were recommended as potential high energy density compounds for their perfect detonation performances and reasonable stability. The pyrolysis mechanism was studied by analyzing the bond dissociation energy (BDE) and the activation energy (E_a) of hydrogen transfer (H–T) reaction for those with adjacent nitro and hydroxyl groups. The results show that E_a is much lower than BDEs of all bonds, so when there are adjacent nitro and hydroxyl groups in a molecule, the stability of the compound will decrease and the pyrolysis will be initiated by the H–T process. Otherwise, the pyrolysis will start from the breaking of the weakest C–NO₂ bond, and only under such condition, the Mulliken population or BDE of the C–NO₂ bond can be used to assess the relative stability of the compound.     

Nitro Derivatives of Parabanic Acid as Potential Explosives: A Theoretical Study

This work deals with certain parabanic acid (PA) derivatives because they possess great calculated density (>1.8 g · cm^–3) and high content of nitrogen (26 %). Computed ballistic properties of eight different parabanic acid derivatives are presented. The structures were optimized at the B3LYP/6‐31G(d, p) level. The calculated data for PA are found to be compatible with the experimental X‐ray data. The detonation performance analyses were done using empirical Kamlet‐Jacobs equations. Additionally, detonation products were assigned and power index were calculated. All the compounds considered are powerful candidates for high energy materials.     

Density function theory study on energetic nitro-triaziridine derivatives

The series of nitro-triaziridines had been studied as high-energy density compounds at B3LYP/6-311G** and MP2/6-311G** levels by means of density functional theory. The heats of formation (HOFs), bond dissociation energies, and detonation performance had been calculated in detail. It was found that all nitro-triaziridines have high position HOFs, and electron-withdrawing of nitro, the steric hindrance, and abundant N–N bond had positive effect with increasing values of HOFs. The thermodynamic stability is estimated by bond dissociation energy and available free space per molecule in unit cell. The detonation performance had been estimated via Kamlet–Jacobs equation and relative specific, However, two different consequences were obtained for detonation performance. Hence, for nitro-triaziridines derivatives, we assumed that a large number of extra oxygen was produced in combustion reaction or explosive reaction, which was negative for the energy released. Therefore, the oxygen balance must be considered for designing high-energy compounds. We also assumed that the Kamlet–Jacobs equation may not be applicable for the compounds, which was constituted of only oxygen, hydrogen, and nitrogen elements.     

Theoretical Study of 13C Chemical Shifts Structures of Some ortho-Substituted 3-Anilino-2-nitrobenzo[b]thiophenes and 2-Anilino-3-nitrobenzo[b]thiophenes and Comparison with Experimental

¹³C NMR chemical shifts have been calculated for structures of some substituted 3‐anilino‐2‐nitrobenzo‐[b]thiophenes ( 2 o) and 2‐anilino‐3‐nitrobenzo[b]thiophenes ( 3 o) derivatives containing OH, NH₂, OMe, Me, Et, H, F, Cl and Br. The molecular structures were fully optimized using B3LYP/6‐31G(d,p). The calculation of the ¹³C shielding tensors employed the GAUSSIAN 03 implementation of the gauge‐including atomic orbital (GIAO) and continuous set of gauge transformations (CSGT) by using 6‐311++G(d,p) basis set at density functional levels of theories (DFT). The isotropic and the anisotropy parameters of chemical shielding for all compounds are calculated. The predicted ¹³C chemical shifts are derived from equation δ=δ₀+δ where δ is the chemical shift, δ is the absolute shielding, and δ₀ is the absolute shielding of the standard TMS. Excellent linear relationships have been observed between experimental and calculated ¹³C NMR chemical shifts for all derivatives     

Theoretical study of the structures and properties of cyclic nitramines: Tetranitrotetraazadecalin (TNAD) and its isomers

Density Functional Theory (DFT) was employed to study the geometries, electronic structures, infrared vibrational spectra, and thermodynamic properties of seven isomeric cyclic nitramines of C₆H₁₀N₈O₈ (i.e., TNAD and its six isomers) at the B3LYP/6‐31G* level of theory. The experimental results available for TNAD were used to determine the reliability of the DFT method for generating structural and IR spectroscopic values for these molecular systems. The relative stabilities of the conformers were evaluated from the energy differences of the structures. Detonation properties of various conformers were evaluated using the Kamlet‐Jacobs equations, and it was found that all the calculated results are comparable to the available experimental data. In addition, the calculated results demonstrate that all title compounds can be used as excellent propellant ingredients. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Looking for high‐energy density compounds among hexaazaadamantane derivatives with ?CN, ?NC,and ?ONO2 groups

Density functional theory (DFT) was employed to evaluate the heats of formation (HOFs) for hexaazaadamantane (HAA) derivatives with ? CN, ? NC, and ? ONO₂ groups, respectively. This was done by designing isodesmic reactions at the B3LYP/6‐31G* level of theory, where the HAA cage skeletons were kept unbroken to produce more accurate results, and all HOFs for the required reference compounds, NH₂CN, NH₂NC, NH₂ONO₂, and (CH₂NH)₃, were derived from the G₃ theory calculation based on the atomization energies. The calculation results show that the HOFs of HAA derivatives are mainly affected by the number and the position of substituent groups, all the obtained HOFs are positive, and the ? NC derivatives have the most HOFs among the three types of derivatives with the same number of substituent groups. The detonation velocity (D) and detonation pressure (P) were obtained from the empirical Kamlet–Jacobs equations. All the ? NC and ? CN derivatives of HAA have lower densities (ρ), heats of explosion (Q), D, and P. However, these properties of ? ONO₂ derivatives are rather high and vary with the number of ? ONO₂ groups. Considering the easiness for synthesis and relative stability, 2,4,6,8‐hexaazaadamantanenitrate is finally recommended as a potential candidate of a high‐energy density compound (HEDC). © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Theoretical investigation on density,detonation properties,and pyrolysis mechanism of nitro derivatives of benzene and aminobenzenes

Nitro derivatives of benzene and aminobenzenes are optimized at the DFT‐B3LYP/6‐31G* level. The heat of formation (ΔH_f) and crystal theoretical density (ρ) are estimated to evaluate the detonation properties using the modified Kamlet–Jacobs equations. Thermal stability and the pyrolysis mechanism of the title compounds are investigated by calculating the bond dissociation energies (BDE) at the unrestricted B3LYP/6‐31G* level. The kinetic parameter and the static electronic structural parameters can be used to predict the stability and the relative magnitude of the impact sensitivity of homologues. According to the quantitative standard of the energy and the stability as an HEDC, the title compounds having more than four nitro groups satisfy this requirement. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

Synthesis and Characterization of a New Energetic Salt based on Dinitramide

The development of new ionic salt as green propellants is one of intense investigations to replace toxic N, N′‐dimethylhydrazine. A new energetic salt N, N′,N′′‐tri(propan‐2‐ylidene)methanetriamium dinitramide (NTAGDN) based on dinitramide was synthesized by reacting silver dinitramide with triaminoguanidinium chloride. The structure of this new energetic salt was confirmed by single‐crystal X‐ray diffraction, elemental analysis, Fourier transform infrared spectrometry, ultraviolet‐visible spectrophotometry, and nuclear magnetic resonance spectroscopy. NTAGDN crystallizes in the orthorhombic space group R$\bar{3}$ . Thermal decomposition was studied by differential scanning calorimetry, differential thermal analysis, and thermogravimetric tandem infrared spectrometry. Results indicated that NTAGDN exhibited excellent resistance to thermal decompositions of up to 470 K and incurred an 80.54 % mass loss between 450 and 523 K via exothermic decomposition. The kinetic parameters of NTAGDN thermal decomposition were also obtained from the differential thermal analysis data by Kissinger's method with E_a = 125.46 kJ · mol^–1. Moreover, based on the Kamlet‐Jacobs formula, the detonation velocity and detonation pressure of NTAGDN were calculated as 6.3 km · s^–1 and 15 GPa, respectively.     

Solubility characteristics of poly(3‐hexylthiophene)

Solubility data for poly(3‐hexylthiophene) (P3HT) in 29 pure solvents are presented and discussed in detail. Functional solubility parameter (FSP) and convex solubility parameter (CSP) computations are performed and the CSP and FSP results are compared to previously reported Hansen solubility parameters (HSPs) and to the parameters calculated using additive functional group contribution methods. The empirical data reveals experimental solubility parameters with substantial polar (δ_P) and hydrogen‐bonding (δ_H) components, which are not intrinsic to the structure of the P3HT polymer. Despite these apparent irregularities, it is shown that the predictor method based on the solubility function, f, does provide a reliable way to quantitatively evaluate the solubility of P3HT in other solvents in terms of a given set of empirical solubility data. The solubility behavior is further investigated using linear solvation energy relationship (LSER) modeling and COSMO‐RS computations of the activity coefficients of P3HT. The LSER model reveals that (1) the cavity term, δ_T, is the dominant factor governing the solubility behavior of P3HT and (2) the solvent characteristics that dictate the structural order (crystallinity) of P3HT aggregates do not similarly influence the overall solubility behavior of the polymer. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1075–1087     

Theoretical Studies on the Structures,Thermodynamic Properties,Detonation Performance,and Pyrolysis Mechanisms for Six Dinitrate Esters

Density functional theory (DFT) has been employed to study the geometric and electronic structures of six dinitrate esters including ethylene glycol dinitrate (EGDN), diethylene glycol dinitrate (Di‐EGDN), triethylene glycol dinitrate (Tri‐EGDN), tetraethylene glycol dinitrate (Tetra‐EGDN), pentaethylene glycol dinitrate (Penta‐EGDN) and hexaethylene glycol dinitrate (Hexa‐EGDN) at the B3LYP/6‐31G* level. Their IR spectra were obtained and assigned by vibrational analysis. Based on the frequencies scaled by 0.96 and the principle of statistic thermodynamics, the thermodynamic properties were evaluated, which were linearly related with the number of CH₂CH₂O groups as well as the temperature, obviously showing good group additivity. Detonation performances were evaluated by the Kamlet‐Jacobs equations based on the calculated densities and heats of formation. It was found that density, detonation velocity, detonation pressure decreased with the increase of the number of CH₂CH₂O groups. Thermal stability and the pyrolysis mechanism of the title compounds were investigated by calculating the bond dissociation energies (BDE) at the B3LYP/6‐31G* level. For the nitrate esters, the O‐NO₂ bond is a trigger bond during a thermolysis initiation process.     

A Sodium Manganese Oxide Cathode by Facile Reduction for Sodium Batteries

A nonstoichiometric sodium manganese oxide (Na_xMnO_2+δ) cathode useful for sodium batteries was synthesized by an ambient‐temperature strategy that involved facile reduction of aqueous sodium permanganate in sodium iodide and subsequent heat treatment at 600 °C. Combined powder X‐ray diffraction and synchrotron X‐ray diffraction analyses confirmed the annealed sample to belong to a Na_xMnO₂ phase with a P2‐hexagonal structure. The ICP‐AES results confirmed the stoichiometry of the sample to be Na_0.53MnO_2+δ. Electron microscopy studies revealed the particle size of the electrode to be in the range of a few hundred nanometers. The Na_0.53MnO_2+δ cathode delivered an average discharge capacity of 170 mA h g^?1 with a stable plateau at 2.1 V for the initial 25 cycles versus sodium. Ex situ XANES studies confirmed the reversible intercalation of sodium into Na_0.53MnO_2+δ and suggested the accommodation of over‐stoichiometric Mn⁴⁺ ions to contribute towards the performance of the electrode.     

Development of Double‐Perovskite Compounds as Cathode Materials for Low‐Temperature Solid Oxide Fuel Cells

A class of double‐perovskite compounds display fast oxygen ion diffusion and high catalytic activity toward oxygen reduction while maintaining excellent compatibility with the electrolyte. The astoundingly extended stability of NdBa_1−xCa_xCo₂O_5+δ (NBCaCO) under both air and CO₂‐containing atmosphere is reported along with excellent electrochemical performance by only Ca doping into the A site of NdBaCo₂O_5+δ (NBCO). The enhanced stability can be ascribed to both the increased electron affinity of mobile oxygen species with Ca, determined through density functional theory calculations and the increased redox stability from the coulometric titration.     

New theoretically predicted RDX‐ and β‐HMX‐based high‐energy‐density molecules

Theoretically new high‐energy‐density materials (HEDM) in which the hydrogens on RDX and β‐HMX (hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine and octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine, respectively) were sequentially replaced by (N NO₂)x functional groups were designed and evaluated using density functional theory calculations in combination with the Kamlet–Jacobs equations and an atoms‐in‐molecules (AIM) analysis. Improved detonation properties and reduced sensitivity compared to RDX and β‐HMX were predicted. Interestingly, the RDX and β‐HMX derivatives having one attached N NO₂ group [RDX‐(NNO₂)1 and HMX‐(NNO₂)1] showed excellent detonation properties (detonation velocities: 9.529 and 9.575 km·s⁻¹, and detonation pressures: 40.818 and 41.570 GPa, respectively), which were superior to the parent compounds. Sensitivity estimations obtained by calculating impact sensitivities and HOMO‐LUMO gaps indicated that RDX‐(NNO₂)1 and HMX‐(NNO₂)1 were less stable than RDX and HMX but more stable than any of the other derivatives. This method of sequential NNO₂ group attachment on conventional HEDMs offers a firm basis for further studies on the design of new explosives. Furthermore, the newly found structures may be promising candidates for better HEDMs.     

Polyimides from an asymmetric hydroxyl‐containing aliphatic‐aromatic diamine synthesized via henry reaction

An aliphatic amino and an aliphatic hydroxyl group have been incorporated via Henry reaction highly efficiently toward the synthesis of a novel asymmetric aliphatic–aromatic diamine 2‐amino‐1‐[4‐(5‐aminopyridyloxy)phenyl]‐1‐ethanol (AAP_yP_hE) in three steps. AAP_yP_hE shows good copolymerization reactivity with 4,4′‐oxydianiline (ODA) toward different aromatic dianhydrides, especially 4,4′‐oxydiphthalic anhydride (ODPA). TGA measurement and mechanical test results show that all polymers maintain the inherent thermal performance and tensile properties, while the glass transition temperatures (T_g's) by DMA show moderate decrease ranging from 185.5 to 253.3 °C due to the presence of aliphatic segments. The introduction of AAP_yP_hE is found to improve the solubility of the polymers, and the polymer films' optical transparency with decreased cutoff wavelength (λ₀) ranging from 328 to 370 nm. Comparative studies reveal that the pendent aliphatic hydroxyls in the polymer chains would lead to interchain cross‐linking via condensation and secondary weak cross‐linking by hydrogen bond depending on different loading of AAP_yP_hE, which result in a fluctuation of hydrophilic–hydrophobic properties, DMA tan δ and dielectric constant of the copolymer films. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3413–3423     

Rationalizing the self‐assembly of poly‐(3‐hexylthiophene) using solubility and solvatochromic parameters

The assembly of poly(3‐hextylthiophene) (P3HT) in solvent mixtures is studied using solubility and solvatochromic parameters. Correlations between the excitonic coupling of P3HT assemblies and the Kamlet–Taft (α, β, π*) and solvent scales reveal that lower excitonic coupling values are observed in binary mixtures characterized by low β values (0 < β ≤ 0.25) and low polarity (0.1 ≤ ≤ 0.3). Hansen solubility theory is revisited by evaluating the directionality of the solubility distance, R_a. Relationships between the excitonic coupling and the Δδ_h and Δδ_p vector components indicate that the polarity of the solvent (Δδ_p) and the specific solvent‐solvent interactions reflected by the Δδ_h component direct the formation of well‐ordered P3HT aggregates. The complementary results of the solubility and solvatochromic parameter analyses are in agreement with one another. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 841–850