A DFT-D Study on Structural,Electronic, Thermodynamic,and Mechanical Properties of HMX/MPNO Cocrystal under High Pressure

An investigation on the structural, electronic, thermodynamic, and mechanical properties of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)/2-methylpyridine-N-oxide (MPNO) cocrystal was carried out from 0 to 100 GPa by using a dispersion-corrected density functional theory (DFT-D) method. Our calculated crystal structure is in excellent agreement with experimental results at ambient pressure. Based on the analysis of lattice parameters, lattice angles, bond lengths, bond angles, and dihedral angles under high pressure, we observe that HMX molecules in the cocrystal bulk are seriously distorted but MPNO molecules remain relatively unchanged. Hydrogen bond lengths are greatly shortened under high pressure. In addition, with the increase in pressure, the bandgap decreases gradually. However, it increases suddenly at 70 GPa. Some important hydrogen bonds between HMX and MPNO are also observed in the density of states spectrum. According to the thermodynamic analysis, this cocrystal is more easily prepared under low pressure. Finally, we characterized its mechanical properties and the results show that this cocrystal is malleable in nature. We expect that this research can provide a fundamental basis for further HMX cocrystal design and preparation.     

Theoretical Insight into the Influences of Molecular Ratios on Stabilities and Mechanical Properties,Solvent Effect of HMX/FOX-7 Cocrystal Explosive

A molecular dynamics method was employed to study the binding energies of the selected crystal planes of the 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane/1,1-diamino-2,2-dinitroethylene (HMX/FOX-7) cocrystal in different molecular molar ratios. Mechanical properties, densities, and detonation velocities of the cocrystals in different ratios were estimated. The intermolecular interactions and bond dissociation energies (BDEs) of the N–NO₂ bond in the HMX:FOX-7 (1:1) complex were calculated using the B3LYP and MP2(full) methods at the 6–311++G (d,p) and 6–311++G(2df,2p) basis sets. Solvent effects on stability are discussed. The results indicate that HMX/FOX-7 cocrystals prefer cocrystalizing in a 1:1 molar ratio, which has good mechanical properties. The N–NO₂ bond becomes strong upon the formation of a complex and the sensitivity of HMX might decrease in cocrystals. The sensitivity change of HMX/FOX-7 originates from not only the formation of intermolecular interaction but also the increment in the N–NO₂ BDE. HMX/FOX-7 cocrystals exhibit good detonation performance and meet the requirements of high-density energetic materials. Solvents with low dielectric constants may be chosen to obtain stable HMX/FOX-7 cocrystals.     

Characterization of RDX-Based Thermosetting Plastic-Bonded Explosive by Cone-Beam Microfocus Computed Tomography

In this study microfocus computed tomography (μCT), a nondestructive technique, was used for 3D characterization of cyclotrimethylenetrinitramine (RDX)-based thermosetting plastic-bonded explosives. Quantitative information on RDX crystals including the packing status of the crystal and binder system, as well as the inner structure characteristics of partially solidified and fully solidified samples, was obtained using cone-beam μCT technology. The CT images show that the CT value of RDX crystal grains was obviously higher than that of crystal powder/binder. The results also show that after vacuum casting and thermosetting, the RDX grains were dispersed evenly and there were no air pores or cracks observed in the sample. Small pores exist inside the RDX grains with a porosity of less than 0.3%. The analysis results indicate high quality of the explosive part after employing thermosetting molding. The binder system and RDX crystals were integrated sufficiently, yet the grain packing was not maximum. The estimated average density and maximal difference in density of the sample were both in accordance with the testing results by Archimedes’ method and it was proven that complete curing may enhance the overall density and density uniformity of the product.     

DFT Calculation of Room Temperature Ionic Liquid 1-Ethyl-3-Methyl-Imidazolium Chlorocuprate (Ⅰ)

The density functional theory (DFT) has been employed to investigate the electronic structures of EMIM ( 1-ethyl-3-methylimidazolium ), CuCl2-, Cu2Cl3- and EMIM -CuCl2-, EMIM -Cu2Cl3- pairs.Full optimization and frequency analyses of EMIM , CuCl2-, Cu2Cl3-, eight initial EMIM -CuCl2-, and six initial EMIM -Cu2Cl3- geometries have been carried out using Gaussian-94 software-package at 6-31 G (d,p) basis set level for hydrogen, carbon, nitrogen, chlorine atoms and the Hay-Wadt effective core potential for copper atoms. The electronic structures of the lowest energy of EMIM -CuCl2-, EMIM -Cu2Cl3-pairs, single EMIM , CuCl2-, and Cu2Cl3- have been comparatively studied. The calculated results showed that the optimized EMIM -CuCl2- pair conformer of the lowest energy was five ring moiety parallel to CuCl2- plane with a distance of around 3.5A, while EMIM -Cu2Cl3- pair conformer of the lowest energy was five ring moiety of EMIM perpendicular to Cu2Cl3- plane with a distance of around 3.0 A between terminal chlorine atoms and 5-ring plane of EMIM~. The cohesion between cation and anion is electrostatic interaction and C-H-Cl hydrogen bonds are reinforced by charge assistance. The frequency analyses suggested that all stationary points are minimum points because of absence of imaginary frequency. The low energy of interaction caused by bulky asymmetry of EMIM , and charge dispersion of cation and anion give rise to low melting point of ionic liquids EMIM -CuCl2-, and EMIM -Cu2Cl3-. The interaction energy caused by the distance between cations and anions was investigated by single point energy scan.     

基于密度泛函理论的量子化学方法研究仪长管输油渣油中金属卟啉化合物

基于密度泛函理论(DFT)的量子化学计算方法,对仪长管输油渣油中几种含量最丰富的金属卟啉化合物进行分子模拟,并对其空间分子结构进行结构优化及计算,得到键参数、偶极矩以及电子吸收光谱等信息。通过分子的键参数和偶极矩发现,镍卟啉化合物的极性小于钒卟啉化合物,DPEP型卟啉分子的极性略大于ETIO型卟啉分子。计算了4种典型金属卟啉分子紫外吸收光谱的Soret吸收带和Q吸收带特征吸收峰,并得到4种卟啉化合物的稳定性由强到弱的顺序为ETIO型镍卟啉C₃₅-(ETIO-Ni)、DPEP型镍卟啉C₃₅-(DPEP-Ni)、ETIO型钒卟啉C₃₄-(ETIO-VO)、DPEP型钒卟啉C₃₁-(DPEP-VO)。     

DFT Calculation of Room Temperature Ionic Liquid 1-Ethyl-3-Methyl-Imidazolium Chlorocuprate （I）

The density functional theory （DFT） has been employed to investigate the electronic structures ofEMIM^＋（1-ethyl-3-methylimidazolium＋）, CuCl2^-, Cu2Cl3^- and EMIM^＋-CuCl2^-, EMIM^＋-Cu2Cl3^- pairs. Full optimization and frequency analyses of EMIM^＋, CuCl2^-, Cu2Cl3^-, eight initial EMIM^＋-CuCl2^-, and six initial EMIM^＋-Cu2Cl3^- geometries have been carried out using Gaussian-94 software-package at 6-3 I＋G （d, p） basis set level for hydrogen, carbon, nitrogen, chlorine atoms and the Hay-Wadt effective core potential for copper atoms. The electronic structures of the lowest energy of EMIM^＋-CuCl2^-, EMIM^＋-Cu2Cl3^- pairs, single EMIM^＋, CuCl2^-, and Cu2Cl3^- have been comparatively studied. The calculated results showed that the optimized EMIM^＋-CuCl2^- pair conformer of the lowest energy was five ring moiety parallel to CuCl2^- plane with a distance of around 3.5,A, while EMIM^＋-Cu2Cl3^- pair conformer of the lowest energy was five ring moiety of EMIM^＋ perpendicular to Cu2Cl3^- plane with a distance of around 3.0 ,A between terminal chlorine atoms and 5-ring plane of EMIM^＋. The cohesion between cation and anion is electrostatic interaction and C-H---Cl hydrogen bonds are reinforced by charge assistance. The frequency analyses suggested that all stationary points are minimum points because of absence of imaginary frequency. The low energy of interaction caused by bulky asymmetry of EMIM^＋, and charge dispersion of cation and anion give rise to low melting point of ionic liquids EMIM^＋-CuCl2^-, and EMIM^＋-Cu2Cl3^- . The interaction energy caused by the distance between cations and anions was investigated by single point energy scan.     

基于密度泛函理论从分子层面分析原油中镍/钒卟啉化合物

基于密度泛函理论(DFT),通过量子化学计算研究了主要的石油卟啉,包括ETIO、DPEP、DI-PEP、RHODO-TIO、RHODO-PEP或RHODO-I-PEP型和Ni²⁺/VO²⁺形成的金属卟啉配合物的分子结构、电子特性、解离能等。卟啉环的空腔尺寸、电荷分布、共轭特性均使其易于与Ni²⁺/VO²⁺发生络合,且配合物结构稳定。空间效应和竞争吸附使得VO²⁺卟啉配合物中的V原子和卟啉环不共面,VO²⁺卟啉环的配位作用弱于Ni²⁺卟啉环,因此Ni的脱除通常比V困难。Ni²⁺/VO²⁺卟啉配合物表现出显著的取代基效应：供电子的环烷基促进了卟啉环和Ni²⁺/VO²⁺的配位;吸电子的苯基削弱了卟啉环和Ni²⁺/VO²⁺的配位。对原油中Ni²⁺/VO²⁺卟啉化合物配位化学特性的研究,对于原油脱Ni/V技术的开发与改进具有一定的理论指导作用。     

La和Ce调变Y分子筛性能的差异及其密度泛函理论研究

In this paper,the different influences of lanthanum (La) and cerium (Ce) species on the stability of Y zeolite were studied by X-ray diffractometry (XRD),X-ray photoelectron spectroscopy (XPS),and multinuclear (27Al,29Si) solidstate nuclear magnetic resonance spectroscopy (NMR).It was found that the stability of Y zeolite could be enhanced by the introduction of La or Ce species;however,the former effect was more remarkable than the latter.These results were also confirmed theoretically by density functional calculations.There was a strong interaction between the rare earth (La or Ce) species and Y zeolite clusters,which restrained the formation of extra-framework aluminum and enhanced evidently the stability of Y zeolite.Furthermore,the interaction between La species and Y zeolite was stronger than that of Ce species with Y zeolite.     

低密度聚乙烯2101TN00的结构与性能表征

从高分子链结构、结晶行为、黏弹性、力学性能、膜性能等５个方面,利用红外光谱（ＩＲ）、差示扫描量热（ＤＳＣ）、流变表征等方法,分别对荷兰ＤＳＭ、齐鲁石化公司生产的同一牌号的低密度聚乙烯产品２１０１ＴＮ００进行测试,比较了２种产品在结构和物理性能上的差异。结果表明,２种产品的结构基本相同,流变性能相近,膜性能各有特点,而在力学性能方面齐鲁产品略优于ＤＳＭ产品。     

DFT Molecular Dynamics Study of Pyrene Biradical Species

Abstract

The pyrene molecule shows its aromaticity localized in specific regions in the molecular framework as it is indicated by the calculated Nuclear Independent Chemical Shift (NICS) values, on previous electronic structure studies (García-Cruz et al. (2004) J. Phys. Chem. A 108, 5111 and Hernández-Trujillo et al. (2005) Chem. Phys. 308, 181), which is in full agreement with Clar's theory. The biradical formed at 400 K follows a simple mechanism, which yields an aromatic species as it is demonstrated by the NICS value. The analysis for testing the homolytic fragmentation and the unusual stabilization are also investigated. A possible implication of the reactivity of pyrene species in asphaltene formation is discussed.     

Prediction of Explosive Performance Properties of z-DBBD and Its Isomers by Quantum Chemical Computations

Theoretical studies have been performed on TACOT, its benzofuroxan derivative z-DBBD, and three different isomers of z-DBBD. The corrected absolute and relative total energies of the geometry-optimized structures were calculated at the theoretical level of B3LYP/6-31G(d,p). The bond dissociation energies were correlated with sensitivity. Mulliken electronegativities (χ_M) and chemical hardness (η) were obtained by employing frontier molecular orbitals at the HF/6-31G(d,p)//B3LYP/6-31G(d,p) theoretical level. Detonation performance analyses for z-DBBD (4,11-dinitro[1 Molchanova , M. S. , T. S. Pivina , E. A. Arnautova , and N. S. Zefirov . 1999 . Computer-aided search for high-density energetic compounds among hydrogen-free heterocycles . Journal of Molecular Structure (Theochem) , 465 : 11 – 24 .[Crossref], [Web of Science ®] , [Google Scholar],2 Kamlet , M. J. and S. F. Jacobs . 1968 . Chemistry of detonations. I. A simple method for calculating detonation properties of C H N O explosives . Journal of Chemical Physics , 48 : 23 – 25 .[Crossref], [Web of Science ®] , [Google Scholar],5 Kamlet , M. J. and H. J. Hurwitz . 1968 . Chemistry of detonations. IV. Evaluation of a simple predictional method for detonation velocities of C-H-N-O explosives . Journal of Chemical Physics , 48 : 3685 – 3692 .[Crossref], [Web of Science ®] , [Google Scholar]]-oxadiazolo[3,4-e][1 Molchanova , M. S. , T. S. Pivina , E. A. Arnautova , and N. S. Zefirov . 1999 . Computer-aided search for high-density energetic compounds among hydrogen-free heterocycles . Journal of Molecular Structure (Theochem) , 465 : 11 – 24 .[Crossref], [Web of Science ®] , [Google Scholar],2 Kamlet , M. J. and S. F. Jacobs . 1968 . Chemistry of detonations. I. A simple method for calculating detonation properties of C H N O explosives . Journal of Chemical Physics , 48 : 23 – 25 .[Crossref], [Web of Science ®] , [Google Scholar],5 Kamlet , M. J. and H. J. Hurwitz . 1968 . Chemistry of detonations. IV. Evaluation of a simple predictional method for detonation velocities of C-H-N-O explosives . Journal of Chemical Physics , 48 : 3685 – 3692 .[Crossref], [Web of Science ®] , [Google Scholar]]oxadiazolo[3′,4′:4,5]benzotriazolo-[2,1-a]benzotriazol-6-ium inner salt 1,8-dioxide), its presently considered isomers, and TACOT were performed. The results showed that the performance of all compounds (compounds 1–4) was as good as that of RDX. The power index results showed that z-DBBD and its isomers were better than TACOT, RDX, and HMX. Compounds 1–4 are all reasonable candidates for high-energy-density materials (HEDMs).     

新型W-HMS催化剂的直接合成、表征及催化性能

采用直接合成方法将W~(6+)固载到六方介孔全硅HMS分子筛上,制成新型W-HMS非均相催化剂。利用UV-Vis漫反射和吡啶(Py)-FTIR方法对W-HMS催化剂进行了表征,研究了该催化剂在环戊烯选择氧化制备戊二醛反应中的催化性能,并探讨了该多相催化反应的机理。实验结果表明,钨物种含量对W-HMS催化剂的结构和催化性能有显著的影响,当n(Si)∶n(W)=30时,该催化剂表现出优良的催化性能,环戊烯的转化率和戊二醛的选择性分别达到100.0%和76.3%。UV-Vis漫反射表征结果显示,该催化剂中钨物种以高度分散状态存在于催化剂骨架中,并且钨物种主要以孤立的[WO_4]~(2-)四面体、单聚或低聚的形态存在;Py-FTIR表征结果显示,高度分散的钨物种提供了更多的酸中心,可推测为该反应的活性中心,并且较强的B酸中心有利于环戊烯的催化氧化。     

C/O杂化调变Ni催化苯分子脱氢及开环反应性能的理论研究

基于密度泛函理论计算,对比研究了Ni,Ni/O,Ni/C,Ni/C/O杂化体系的电子特性以及催化苯分子脱氢和开环反应的性能.实验结果表明,单独C或O原子对Ni外层轨道的杂化降低了Ni的化学活性,而C/O同时与Ni外层轨道杂化促进了Ni外层电子的离域,提高了Ni/C/O杂化体系与苯分子的键合作用.不同催化剂催化苯分子脱氢...     

Influence of Small Change of Porosity on Shock Initiation of an HMX/TATB/Viton Explosive and Ignition and Growth Modeling

All solid explosives in practical use are more or less porous. Although it is known that the change in porosity affects the shock sensitivity of solid explosives, the effect of small changes in porosity on the sensitivity needs to be determined for safe and efficient use of explosive materials. In this study, the influence of a small change in porosity on shock initiation and the subsequent detonation growth process of a plastic-bonded explosive PBXC03, composed of 87% cyclotetramethylene-tetranitramine (HMX), 7% triaminotrinitrobenzene (TATB), and 6% Viton by weight, are investigated by shock to detonation transition experiments. Two explosive formulations of PBXC03 having the same initial grain sizes pressed to 98 and 99% of theoretical mass density (1.873 g/cm³) respectively are tested using the in situ manganin piezoresistive pressure gauge technique. Numerical modeling of the experiments is performed using an ignition and growth reactive flow model. Reasonable agreement with the experimental results is obtained by increasing the growth term coefficient in the Lee-Tarver ignition and growth model with porosity. Combining the experimental and simulation results shows that the shock sensitivity increases with porosity for PBXC03 having the same explosive initial grain sizes for the pressures (about 3.1 GPa) applied in the experiments.     

Synthesis and Characterization of a New Co-Crystal Explosive with High Energy and Good Sensitivity

A new energetic co-crystal consisting of one of the most powerful explosive molecules 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and the military explosive cyclotrimethylenetrinitramine (RDX) was prepared with a simple solvent evaporation method. Scanning electron microscopy (SEM) revealed the morphology of the bar-shaped product, which differed greatly from the morphology of the individual components. Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction spectrum (XRD), and differential scanning calorimetry (DSC) proved the formation of the co-crystal at the molecular level. The result of mechanical sensitivity test indicated the sensitivity was effectively reduced compared to raw CL-20. Finally, a possible crystallization mechanism was discussed.     

中低温煤焦油沥青质的分析表征

采用XPS、XRD、FT IR、13C NMR、元素分析等手段分析表征了中低温煤焦油正庚烷沥青质(CT C7沥青质),系统研究了CT C7沥青质表面元素的赋存状态、相对含量以及其晶体结构。结果表明,该沥青质的主要结构为多环稠合芳香烃并富含杂原子,其芳香度(fa)明显大于一般原油沥青质;烷基链间距和芳香片层直径值较小,其芳环上烷基侧链短而少且难以形成堆积结构;表面C主要以sp2和sp3碳的形式存在,二者摩尔分数之和达699%,以C=O和COO-基团存在的C较少。该沥青质表面的杂原子以O原子为主,N和S原子较少,其中含氧官能团主要是酚羟基和醚氧基,摩尔分数达619%。含氮官能团主要以吡啶氮(N 6)和吡咯氮(N 5)为主,二者摩尔分数之和为805%;含硫官能团中,噻吩硫、烷基硫比较多,摩尔分数之和达517%。该C7沥青质表面加氢难度较大的N 6、N 5和噻吩硫的摩尔分数低于石油沥青质,这可能是煤焦油加氢工艺中N、S脱除效率较高的原因之一。     

双子表面活性剂NNMB的合成及表征

选取丙酮为溶剂,以甲苯-2,4-二异氰酸酯（TDI）,烷基溴和二乙基氨基乙醇为原料,合成了双子表面活性剂2,4-二（氨基甲酸-二乙基烷基季铵盐基乙基酯）-1-甲基苯（NNMB）。结果表明,通过加料次序和溶剂的改变,产物产率高达94％,产物易分离纯化。利用红外光谱验证了产物的结构。目标产物的水溶液在25℃的表面活性数据为：7cMc为27．3mN／m,CMC为0．7mmol／L,目标产物与十二烷基磺酸钠（SDS）复配产生了明显的协同效应,当目标产物与SDS摩尔比为1：2时,复合表面活性剂溶液的表面活性数据为：CMC为8．0×10^-2mmol／L,ycMc为22．5mN／m。     

Synthesis,Characterization, and Thermal and Explosive Properties of Alkali Metal Salts of 5,7-Diamino-4,6-Dinitrobenzofuroxan (CL-14)

Potassium, rubidium, and cesium salts of 5,7-diamino-4,6-dinitrobenzofuroxan (CL-14) have been prepared by reacting sodium salt of 5,7-diamino-4,6-dinitrobenzofuroxan with alkali metal nitrate in an aqueous medium. The structure of the compounds was unequivocally confirmed by spectra data, elemental analyses, and estimation of metal content. Further, the compounds have been evaluated for explosive and thermal properties and found more suitable as compared to alkali metal salts of 4,6-dinitrobenzofuroxan (DNBF).