新潜在高能量密度化合物（HEDC）多硝酸酯基金刚烷由气态到固态的理论研究

为寻求新的潜在高能量密度化合物（HEDCs）,对系列（26个）多硝酸酯基金刚烷进行由气态到固态的理论研究.在B3LYP/6-31G水平下,通过设计合理的等键反应,求得26个标题物的生成热（HOFs）,其结果表明：具有相同—ONO2基数目（n）的同分异构体的HOFs值与取代基的位置相关性不好,即并非取代基间距离越近,其HOF越大.基于所求HOFs和理论密度（ρ）,运用修正的适合CHNO系的Kamlet-Jacobs方程,估算了该26个化合物的爆炸性质（能量性质）：爆热（Q）、爆速（D）和爆压（P）,结果表明：当n=7-8时,对应硝酸酯基金刚烷符合HEDC的能量要求,即ρ〉1.9g·cm^-3,D〉9.0km·s^-1,P〉40.0GPa.为考虑HEDC的适用性,对两种可能引发键（C—O和O—NO2）离解能（EC—O和EO—N）进行计算和比较发现EC—O总是小于EO–N,这表明O—NO2为该系列化合物的热解引发键;且发现具有偕二硝酸酯基的金刚烷在同分异构体中的热稳定性总是最差,并且所有偕二硝酸酯基金刚烷的稳定性均相当;由于该系列化合物结构的复杂性,随化合物中取代基数（n）的增加,化合物的EO–N并不明显降低,且该系列化合物的稳定性并非由某个结构参数决定.因而,结合HEDC的能量和稳定性要求（引发键离解能〉12kJ·mol^-1）,仅1,2,4,6,8,9,10-七硝酸酯基金刚烷被推荐为潜在品优HEDC.运用分子力学（MM）方法,分别以Compass和Dreiding力场,在七种最可几空间群（P21/c,P-1,P212121,P21,Pbca,C2/C和Pna21）中,对1,2,4,6,8,9,10-七硝酸酯基金刚烷分子的堆积方式进行预测.两种力场的预测结果均表明,该化合物属P21/c空间群.进行对该预测晶胞的电子结构的周期性从头算,报道其能带结构和态密度,关联其稳定性.发现Fermi能级附近的能带主要由—O—NO2的O和N原子的p态所贡献,且—NO2中N和—O—的p态相重叠形成O—NO2键;这与其气相分子键离解能计算结果相一致,即O—NO2键为该系列化合物的热解引发键.     

双环-HMX结构和性质的理论研究

在DFT-B3LYP/6-311G*水平上, 计算研究了高能化合物四硝基四氮杂双环辛烷(双环-HMX) α和β两种异构体的结构和性质. 比较分子对称性、分子内氢键和环张力等几何参数以及分子总能量和前线轨道能级等电子结构参数, 发现α比β稳定. 分子中N—N键较长, N—N键集居数较小, 预示该键为热解和起爆的引发键. 基于简谐振动分析求得IR谱频率和强度. 运用统计热力学方法求得200～1000 K温度的热力学性质. 以非限制性半经验PM3方法探讨其热解机理, 求得各反应通道的过渡态和活化能, 发现热解始于侧链N—NO₂键的均裂. 还从理论上预测了该化合物的密度、爆速和爆压, 有助于寻求高能量密度材料(HEDM).     

几种新型六氮杂异伍兹烷衍生物结构与性能的理论预测—— 高能量密度化合物的寻求

以CN, NC, ONO2, N3, NH2, N2H, NHNH2, N4H和N4H3 9种含氮高能基团为取代基, 分别取代2,4,6,8,10,12-六氮杂异伍兹烷(IW)中亚氨基的6个H原子所形成的9种六氮杂异伍兹烷衍生物作为研究目标分子. 运用密度泛函理论, 在B3LYP/6-31G**水平上求得了它们的分子几何构型、电子结构、解离能(BDE)及IR谱等信息, 并设计等键反应计算了生成热( ). 基于统计热力学原理计算拟合了100～1200 K温度范围内体系的热力学函数, 利用Kamlet-Jacobs方程估算了它们的爆轰性能. 研究结果表明, 9种六氮杂异伍兹烷衍生物存在两种可能的热解引发类型. 在衍生物HNiIW, HBDAIW和HBAIW中, 可能的热解引发键是取代基内部的化学键, 而其余衍生物的热解引发键则可能是骨架N与取代基R之间N—R键. 另外, 硝酸酯基(ONO2)取代所得化合物HNiIW的密度ρ、爆速D及爆压p分别为1.998 g•cm－3, 9.71 km•s－1和44.47 GPa, 完全达到高能量密度化合物(HEDC)的基本要求, 且优于已应用的HNIW, 有望成为新型的HEDC.     

过渡金属催化的基于季铵盐C—N键断裂的偶联反应研究进展

含有碳-氮(C—N)键的胺类化合物广泛存在于天然产物、药物分子和功能材料之中.C—N键作为分布最广且相对惰性的化学键之一,通过对其选择性的断裂来构建新的碳-碳(C—C)或碳-杂(C—X)键在近年来逐渐发展为一种新的合成方法.季铵盐化合物易于从胺类化合物合成,发生C—N键断裂相对容易.综述了近年来以季铵盐为原料通过过渡金属催化的C—N键断裂实现的交叉偶联反应.     

1,3,4,5,7,8-六硝基八氢化二咪唑[4,5-b∶4',5'-e]吡嗪-2,6-(1H,3H)-N,N'-二亚硝胺分子结构与性能的量子化学研究

设计了一种新型高能量密度化合物1,3,4,5,7,8-六硝基八氢化二咪唑[4,5-b∶4',5'-e]吡嗪-2,6-(1H,3H)-N,N'-二亚硝胺(ONIP).运用密度泛函理论(DFT),在B3PW91/6-31G++(d,p)水平下进行优化并计算出了ONIP的一些重要性质.通过键级的分析,母环的五元环侧链处N—NO2键为分解引发键,其解离能为107.8 kJ/mol;该化合物理论密度为2.00 g/cm3,生成热为1693.71 kJ/mol,爆速为10.21 km/s,爆压为49.17 GPa,表明爆轰性能优异;其撞击感度为33 cm,优于黑索金(RDX)、奥克托金(HMX)和六硝基六氮杂异伍兹烷(CL-20);能级差为3.67 eV,表明分子稳定性较高.给出了2条合成路线,均具有步骤少且原料易得的优点.     

N—O键解离焓的密度泛函理论研究

在高精度计算方法G3和G3B3的基础上,比较了密度泛函理论(DFT)十几种方法对N—O键解离焓(BDE)相对于实验值的计算精度,发现用B3P86方法计算15种化合物N—O键的BDE,均方根误差最小,仅为6.36kJ·mol-1,计算值与实验值的线性相关系数为0.991.在此基础上,用该方法分别计算了非芳香化合物及芳香化合物的N—O键BDE.通过自然键轨道分析,发现部分N—O键的BDE与N—O键的键长、原子电荷密度及键级之间存在定量关系.此外,在B3P86方法的基础上预测了几种典型的杂环芳香化合物N—O键BDE值.     

新型高能量密度化合物3,6-双(3,5-二硝基-1,2,4-三唑-1)-1,2,4,5-四嗪-1,4-二氧化物的性能预估及合成路线设计

采用C++自编译程序及组合原理,设计并筛选出一种未见报道的新型富氮类高能量密度化合物-3,6-双(3,5.二硝基.1,2,4-三唑.1)-1,2,4,5-四嗪-1,4-二氧化物,用B3LYP法,在6-31G**基组水平上得到该化合物全优化构型;在振动分析的基础上求得体系的振动频率、IR谱;通过键级分析得到热解引发键的键离解能(BDE);采用Monte-Carlo 方法预估了密度;设计等键等电子反应计算了生成焓;运用Kamlet-Jacobs公式预测爆速、爆压和爆热;运用Keshavarz 等推导的预估撞击感度H50的公式预测了撞击感度性能;并利用逆合成分析法设计其合成路线.结果表明:该化合物存在8个强吸收峰,校正后的热解引发键的BDE为264KJ·mol-1,稳定性较优;密度1.955 g·cm-3、生成焓901.72 kJ·mol-1、爆速9191.48 m·s-1、爆压39.32 GPa、爆热6705.15 j·g-1;撞击感度H50为55.85cm,低于黑索金(RDX)和奥克托今(HMx);以上性能均达到了高能量密度化合物的标准,且该化合物设计合成路线步骤较少、原料易得,有望得到广泛应用.     

3,7-二硝亚胺基-2,4,6,8-四硝基-2,4,6,8-四氮杂双环[3.3.0]辛烷结构与性能的量子化学研究

设计了一种新型高能量密度化合物--3,7-二硝亚胺基-2,4,6,8-四硝基-2,4,6,8-四氮杂双环[3.3.0]辛烷, 应用密度泛函理论(DFT)的B3LYP 方法在6-31G(d,p)基组水平上对该化合物进行了结构全优化, 并计算得到其红外(IR)光谱; 通过键级分析获得热解引发键的位置为N7-N22, 同时求得校正后的键离解能为91.47 kJ/mol. 采用Monte-Carlo方法预测该化合物的理论密度为2.16 g/cm³; 基于理论密度并结合等键反应及Kamlet-Jacobs公式预测了生成焓、爆速、爆压和爆热值分别为1219.94 kJ/mol, 10.43 km/s, 53.44 GPa和7407.84 J/g. 以上性能参数显示, 该目标化合物达到了高能量密度化合物的基本要求, 是一种潜在的含能材料. 同时给出了该化合物的逆合成路线.     

高能量密度材料3,3′-偶氮-1,2,4,5-四嗪衍生物的分子设计

运用密度泛函理论(DFT)方法,计算系列3,3′-偶氮-1,2,4,5-四嗪衍生物的生成热.结果显示:—N3取代基在增加3,3′-偶氮-1,2,4,5-四嗪衍生物的生成热方面起了非常重要的作用.通过分析标题化合物的最弱键离解能发现:—NH2或—N3取代基非常有利于增加衍生物的热稳定性.计算的爆速(D)和爆压(p)数值表明:—NO2或—NF2取代基有利于提高3,3′-偶氮-1,2,4,5-四嗪衍生物的爆轰性能.综合爆轰性能和热稳定性的计算结果,3种3,3′-偶氮-1,2,4,5-四嗪衍生物可以作为潜在的品优高能量密度材料(HEDM)候选物.     

2,6-二氨基-3,5-二硝基吡嗪-1-氧化物(LLM-105)晶体结构、安全性及密度泛函理论研究

利用DMSO和水的混合溶剂培养出2,6-二氨基-3,5-二硝基吡嗪-1-氧化物(LLM-105)的单晶,晶体属单斜晶系,空间群为Pna2(1)。运用Dmol3中的密度泛函理论计算了LLM-105的晶体性质,态密度计算表明C-N 为该物质的热解引发键。通过设计等键反应预测得到LLM-105的生成热(HOF),结合HOF与晶体密度利用 Kamlet-Jacobs公式得到该物质的爆速、爆压;键断裂能的计算结果表明 C-NO2为热解引发键。运用微热量仪对其进行比热容测定,由比热容与温度的关系式及LLM-105的热分解参数得到了该化合物从开始分解到爆炸所需的时间即绝热至爆时间。     

DFT studies on a high energy density cage compound 4-trinitroethyl-2,6,8,10,12-pentanitrohezaazaisowurtzitane

Polynitro cage compound 4-trinitroethyl-2,6,8,10,12-pentanitrohexaazaisowurtzitane has the same framework with but higher stability than CL-20 and is a potential new high energy density compound (HEDC). In this paper, the B3LYP/6-31G(d,p) method of density functional theory (DFT) has been used to study its heat of formation, IR spectrum, and thermodynamic properties. The stability of the compound was evaluated by the bond dissociation energies. The calculated results show that the first step of pyrolysis is the rupture of the N-NO(2) bond in the side chain and verify the experimental observation that the title compound has better stability than CL-20. The crystal structure obtained by molecular mechanics belongs to the P2(1)2(1)2(1) space group, with lattice parameters a = 12.59 ?, b = 10.52 ?, c = 12.89 ?, Z = 4, and ρ = 2.165 g·cm(-3). Both the detonation velocity of 9.767 km·s(-1) and the detonation pressure of 45.191 GPa estimated using the Kamlet-Jacobs equation are better than those of CL-20. Considering that this cage compound has a better detonation performance and stability than CL-20, it may be a superior HEDC.     

Theoretical studies on high energetic density nitramine explosives containing pyridine

The insensitive property of explosives containing pyridine is combined with the high energy of nitramine explosives,and the concept of new nitramine explosives containing pyridine is proposed,into which nitramine group with N N bonds is introduced as much as possible.Based on molecular structures of nitramine compounds containing pyridine,density functional theory(DFT) calculation method was applied to study designed molecules at B3LYP/6-31+G(d) level.The geometric and electronic structures,density,heats of formation(HOF),detonation performance and bond dissociation energies(BDE) were investigated and comparable to 1,3,5-trinitro-1,3,5-triazinane(RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX).The simulation results reveal that molecules B and D perform similarly to traditionally used RDX.Molecule E outperform RDX,with performance that approach that of HMX and may be considered as potential candidate of high energy density compound(HEDC).These results provide basic information for molecular design of novel high energetic density compounds.     

Theoretical calculation of nitro-1-(2,4,6-trinitrophenyl)-1H-azoles energetic compounds

In order to study the properties of new energetic compounds formed by introducing nitroazoles into 2,4,6-trinitrobezene, the density, heat of formation and detonation properties of 36 nitro-1-(2,4,6-trinitrobenzene)-1H-azoles energetic compounds are studied by density functional theory, and their stability and melting point are predicted. The results show that most of target compounds have good detonation properties and stability. And it is found that nitro-1-(2,4,6-Trinitrophenyl)-1H-pyrrole compounds and nitro-1-(2,4,6-trinitrop-enyl)-1H-Imidazole compounds have good thermal stability, and their weakest bond is C NO₂ bond, the bond dissociation energy of the weakest bond is 222–238 kJ mol⁻¹ and close to 2,4,6-trinitrotoluene (235 kJ mol⁻¹). The weakest bond of the other compounds may be the C NO₂ bond or the N N bond, and the strength of the N N bond is related to the nitro group on azole ring.     

Predicting Trigger Bonds in Explosive Materials through Wiberg Bond Index Analysis

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.     

Theoretical studies on the heats of formation, detonation properties, and pyrolysis mechanisms of energetic cyclic nitramines

Density functional theory calculations were performed to find comprehensive relationships between the structures and performance of a series of highly energetic cyclic nitramines. The isodesmic reaction method was employed to estimate the heat of formation. The detonation properties were evaluated by using the Kamlet-Jacobs equations based on the theoretical densities and HOFs. Results indicate the N-NO(2) group and aza N atom are effective substituents for enhancing the detonation performance. All cyclic nitramines except C11 and C21 exhibit better detonation performance than HMX. The decomposition mechanism and thermal stability of these cyclic nitramines were analyzed via the bond dissociation energies. For most of these nitramines, the homolysis of N-NO(2) is the initial step in the thermolysis, and the species with the bridged N-N bond are more sensitive than others. Considering the detonation performance and thermal stability, twelve derivatives may be the promising candidates of high energy density materials (HEDMs). The results of this study may provide basic information for the further study of this kind of compounds and molecular design of novel HEDMs.     

4‐Amino‐3‐methyl‐6‐phenyl‐1,2,4‐triazin‐5(4H)‐one (metamitron) and 4‐amino‐6‐methyl‐3‐phenyl‐1,2,4‐triazin‐5(4H)‐one (isometamitron)

The title structures, both C₁₀H₁₀N₄O, are substitutional isomers. The N—N bond lengths are longer and the C=N bond lengths are shorter by ca 0.025 Å than the respective average values in the C=N—N=C group of asymmetric triazines; the assessed respective bond orders are 1.3 and 1.7. There are N—H⋯O and N—H⋯N hydrogen bonds in both structures, with 4‐­amino‐3‐methyl‐6‐phenyl‐1,2,4‐triazin‐5(4H)‐one containing a rare bifurcated N—H⋯N,N hydrogen bond. The structures differ in their mol­ecular stacking and the hydrogen‐bonding patterns.     

十二氢十二硼酸双(二烷基-5-氨基四唑)盐的晶体结构及性能分析

制备了11种十二氢十二硼酸双(二烷基-5-氨基四唑)盐晶体, 采用X射线单晶衍射仪对其单晶结构进行了表征, 利用EXPLO5软件计算了11种化合物的爆轰性能. 结果表明, 11种化合物的密度在1.097~1.229 g/cm³之间, 当取代基位置相同时, 随着烷基取代基碳原子数的增大化合物的密度下降; 这些盐晶体的空间晶型主要受取代基位置的影响, 晶体结构有三斜晶系和单斜晶系2种; 晶胞尺寸与晶胞内分子数有关, 化合物中阳离子取代烷基中碳原子的个数对与四唑相连的C—N键长无明显影响. 对于同一取代位置的化合物, 生成热和爆热随着烷基取代基的碳原子数的增多而下降.     

分子内结构环境对解离能的影响

为了理解化学键的这一结构效应, 本文对具有相同化学键而分子内结构环境不同的系列分子进行了计算研究, 讨论了化学键结构环境对解离能的影响.     

The effect of nitro groups on the structures and energetic properties of the derivatives composed of TATB and cubane

Based on the successful experience of synthesis of the TATB (1, 3, 5-triamino-2, 4, 6-trinitrobenzene) and cubane, we propose to consider their nitro derivatives combined by C–N bond as a series of high energy density compounds. First principles molecular orbital calculations have been used to investigate the structural and energetic properties, including the heat of formation, density, detonation performance, and impact sensitivity. Natural bond orbital analysis was carried out to investigate the influence of substituents on the electron delocalization. The results implied that the inclusion of nitro group will decrease the stability of cage skeleton and weaken the C–NO₂ bond. The calculated heats of formation, density, detonation velocity, and detonation pressure are positive and large. The results revealed that two of five derivatives have the close performance and sensitivity to those of CL-20, indicating that they may be explored as new potential high energy materials. Leave them with the notable value to dig out.