由四乙酰基二甲酰基六氮杂异伍兹烷合成六硝基六氮 杂异伍兹烷

六硝基六氮杂异伍兹烷(HNIW)是一笼形硝胺,它是迄今已知的能量最高的高能量密度化合物(HEDC),本文由四乙酰基二甲酰基六氮杂异伍兹烷(TADFIW)合成了HNW。所合成的HNW中含有少量(2%～3%)的未硝解完全的副产物,经分离鉴定,确定其为五硝基一甲酰基六氮杂异伍兹烷(PNMFIW)。以此路线合成HNW有以下优点：催化剂耗量低,反应条件温和,得率高,流程简单等。     

基于质谱的六硝基六氮杂异伍兹烷热分解动力学

采用低能电子轰击质谱研究了六硝基六氮杂异伍兹烷(HNIW)的裂解过程, 建立了质谱中离子强度曲线的非等温动力学处理方法, 根据产物离子的Arrhenius曲线解释了HNIW热分解的机理. 结果表明, HNIW质谱裂解的表观活化能为145.1 kJ·mol-1. 在130-150 ℃范围内, HNIW质谱的离子产物主要是电子轰击产生的, 其活化能在28-41 kJ·mol-1之间; 在213-228 ℃范围内, 离子主要是热分解产生的, 其活化能在143-179 kJ·mol-1之间. HNIW在213-228 ℃的热分解动力学参数存在良好的动力学补偿效应, 补偿效应公式为lnA=0.252Ea-0.645. HNIW 热分解的主要反应为HNIW.438→6NO2+2HCN+HNIW.108, HNIW.438→6NO2+3HCN+HNIW.81, HNIW.438→6NO2+4HCN+HNIW.54.     

六硝基六氮杂异伍兹烷与二甲基甲酰胺分子加合物的制备、性能及晶体结构

六硝基六氮杂异伍兹烷(HNIW)可与二甲基甲酰胺(DMF)形成稳定的分子加合物(两者分子比为1:2)。首次报道了该加合物的晶体结构、晶体学数据和结构参数。该加合物为无色透明片状晶体,属三斜晶系,空间群Pi。在该加合物中,HNIW与DMF分子以范德华力结合,彼此间不存在氢键或偶极作用。     

反相高效液相色谱法测定ε-六硝基六氮杂异伍兹烷纯度

六硝基六氮杂异伍兹烷(HNIW)是1998年才合成的一种多环笼型硝胺高能炸药,它的学名是2,4,6,8,1O-六硝基-2,4,6,8,1O,12-六氮杂四环[5.5.O.O~(5.9).O~(3.11)]十二烷,ε-HNIW的密度、爆速及爆压超过现在含能材料领域内独鳌头的王牌炸药奥克托今(HMX)5%～8%,而由圆筒实验及钽板加速实验测得的能量输出则可超过HMX14%.目前,美国已在进行HNIW的中试生产,中国及其他国家正在积极研究HNIW的生产和应用.因此,建立HNIW纯度的分析方法,对于HNIW生产工艺改进、产品质量控制及合HNIW混合炸药和推进剂的成分分析都是迫切需要的.美国的S.A.Oehrle曾采用胶束电动色谱(MECC)及高效液相色谱(HPLC)测定了混合炸药中包括HNIW在内的十多种组分的保留时间;瑞典的B.Persson等也以HPLC测出了混合炸药中三硝基氮杂环丁烷(TNAZ)和HNIW的含量;日本的儿玉保也曾提及他们合成的HNIW经HPLC测定其纯度为99%.但上述报道均不够详细,而且多限于分析含HNIW的混合炸药.作者制得了高纯度的ε-HNIW样品,并以HPLC对所得的HNIW样品进行了纯度测定,得到峰面积归一化定量法分析结果,并对结果进行了讨论.     

γ-六硝基六氮杂异伍兹烷的晶体结构

合成了六硝基六氮杂异伍兹烷(HNIW),用溶剂缓慢挥发法制得了γ-HNIW的单晶,以X射线衍射仪测定了晶体结构,属于单斜晶系,空间群P2~1/n。晶胞参数为:a=1.3213(11)nm,b=0.8161(6)nm,c=1.4898(4)nm;β=109.168(9)ⅲ;Z=4;V=1.5175(4)nm^3。Dc=1.918g/cm^3,Dm=1.92g/cm^3。最终偏离因子R=0.0360。     

β-六硝基六氮杂异伍兹烷的合成及晶体结构

从苄胺和乙二醛出发 ,通过缩合、氢解脱苄及硝解三步合成了高张力多环笼形化合物———六硝基六氮杂异伍兹烷 (HNIW) ,它是迄今为止密度及能量水平最高的高能量密度化合物 .β HNIW的晶体结构表明 ,它是由 2个五元环及 1个六元环构成的笼形结构 ,每个桥氮原子上各连有 1个硝基 ,—NO2 基本位于一平面内 ,C—C键长为 0 1 5 6～ 0 .1 5 9nm ,比标准的sp3 C—C键长 0 0 0 2～ 0 .0 0 5nm .晶体学数据为 :正交晶系 ,空间群Pca2 1,a =0 .96 70 ( 2 )nm ,b =1 .1 6 1 6 ( 2 )nm ,c =1 .30 32 ( 3)nm ;V =1 .46 38( 5 )nm3 ,Z =4,Dc=1 .989g·cm-3 (Dm=1 .982 g·cm-3 ) .     

六硝基六氮杂异伍兹烷及其残余物的热分解

在(2.0±0.1) MPa氩气氛围下六硝基六氮杂异伍兹烷(HNIW)在(204.0±0.5)、(208.0±0.5)、(212.0±0.5)和(216.0±0.5) ℃下分别加热10、20、30、40、50 和60 min. 采用元素分析、扫描电子显微镜(SEM)、傅立叶变换红外(FTIR)光谱仪、差示扫描量热(DSC)仪、热重-差示扫描量热仪-质谱(TG-DSC-MS)仪和热重-红外(TG-FTIR)仪对(208.0±0.5) ℃下得到的残余物进行研究. 结果表明, HNIW离子在210.0 ℃左右恒温热解60 min 后, 残余物的组成为C2H2N2O. 残余物中未分解的HNIW比初始HNIW稳定性差. 在等温条件下, HNIW是逐步分解的. HNIW残余物的热分解分为三个阶段, 第一个分解阶段主要为未分解的HNIW的热分解, 第二阶段主要为五员环硝铵和碳氮杂环化合物的分解反应, 第三阶段主要为五员环硝铵的分解反应和NO2的二次反应, 并获得了每一个阶段的热分解产物.     

纳米三氧化钨的制备、表征及对六硝基六氮杂异伍兹烷热分解的影响

采用水热法通过控制前躯体钨酸钠的加入量和反应时间制备了长方体形纳米WO₃,利用X射线粉末衍射(XRD)、透射电镜(TEM)、扫描电镜及能量散射光谱仪(SEM-EDS)对样品进行表征。并运用差示扫描量热法(DSC)研究纳米WO₃对六硝基六氮杂异伍兹烷(CL-20)热分解特性的影响。结果表明:与单组分CL-20相比,纳米WO₃的加入使复合物WO₃/CL-20的热分解峰温降低2.95℃,活化能减小7.74 kJ·mol^-1,因此纳米WO₃能够加速CL-20的热分解。     

纳米三氧化钨的制备、表征及对六硝基六氮杂异伍兹烷热分解的影响

采用水热法通过控制前躯体钨酸钠的加入量和反应时间制备了长方体形纳米WO₃,利用X射线粉末衍射(XRD)、透射电镜(TEM)、扫描电镜及能量散射光谱仪(SEM-EDS)对样品进行表征。并运用差示扫描量热法(DSC)研究纳米WO₃对六硝基六氮杂异伍兹烷(CL-20)热分解特性的影响。结果表明:与单组分CL-20相比,纳米WO₃的加入使复合物WO₃/CL-20的热分解峰温降低2.95℃,活化能减小7.74 kJ·mol^-1,因此纳米WO₃能够加速CL-20的热分解。     

六苄基六氮杂异伍兹烷的氧化反应性

研究了2，4，6，8，10，12－六苄基－2，4，6，8，10，12－六氮杂四环[5．5．0．0^5,9．0^3.11]十二烷在多种氧化条件下的氧化反应性，得到了一系列新的六氮杂异伍兹烷衍生物，并利用两步法以较高的收率得到期望的化合物六苯甲酰基六氮杂异伍兹烷。     

HCS自由基超精细结构的密度泛函理论计算

１９９８年,李远哲等［１］对ＨＣＳ自由基进行了傅里叶变换毫米波光谱实验研究,测定了质子的超精细耦合常数Ａ（Ｈ）为１２７．４２７ＭＨｚ．他们注意到此值远小于ＨＣＯ自由基的Ａ（Ｈ）值,并认为这与ＨＣＳ的键角比ＨＣＯ的键角大有关．我们用密度泛函理论中的（Ｕ）Ｂ３ＬＹＰ［２,３］方法对ＨＣＳ及有关的ＨＣＯ、ＨＳＩＳ和ＨＳＩＯ自由基进行了计算研究．本研究结果表明：Ｂ３ＬＹＰ方法计算的ＨＣＳ的Ａ（Ｈ）与实验值非常一致;键角的大小不足以解释ＨＣＳ的Ａ（Ｈ）值远小于ＨＣＯ这一事实;用自旋密度却可简明地加以解释．…     

Enthalpies of formation from B3LYP calculations

We have calculated the geometries, energies, and normal vibrations of 845 compounds containing the elements H, C, N, O, F, Al, Si, P, S, and Cl using hybrid density functional theory in order to investigate the accuracy of atom-additive schemes for predicting enthalpies of formation at 298 K. The results give a more realistic estimate of the accuracy of density functional calculations than some overoptimistic earlier correlations. We have also calculated atom-additive schemes for the zero-point energies and enthalpic corrections to the energies. Remarkably, it is not important to include the vibrational or rotational contributions, which can be estimated well within a purely Born-Oppenheimer regression model.     

B3LYP calculations on bishomoaromaticity in substituted semibullvalenes*

B3LYP/6‐31G* calculations on the degenerate rearrangements of substituted semibullvalenes spuriously predict the relative enthalpies of the bishomoaromatic TSs to be lower than the experimental values. However, the calculations do make the useful and experimentally testable prediction that the two cyano and two phenyl substituents in 2,6‐dicyano‐4,8‐diphenylsemibullvalene ( 9d ) are more likely than four cyano substituents in 2,4,6,8‐tetracyanosemibullvalene ( 9f ) or the four phenyl substituents in 2,4,6,8‐tetraphenylsemibullvalene ( 9g ) to produce a semibullvalene that has a bishomoaromatic equilibrium geometry in the gas phase. The major reason for the surprising finding that 9d is more likely to be bishomoaromatic than 9g is shown to be steric interactions between the phenyl groups at C‐2 and C‐8 and at C‐4 and C‐6 in bishomoaromatic structure 10g . These interactions inhibit the conjugative stabilization of 10g ; but they are absent in bishomoaromatic structure 10d , where cyano groups replace the phenyl groups at C‐2 and C‐6 in 10g . © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1565–1573, 2001     

Geometry optimization of the cytosine molecules in a cytosine stack using the B3LYP crystal orbital method

The B3LYP DFT crystal orbital method was applied (with helical periodicity) to calculate the total energy per unit cell of a cytosine (C) molecule in a C stack. Applying afterwards the multidimensional metric method in its BFGS form, the geometry of a C molecule was optimized in the stack of DNA B (3.36 Å stacking distance, 36° rotation). For comparison, we optimized also the geometry of a C trimer and pentamer (in DNA B form) using the Gaussian 03 program for the B3LYP molecular calculation and the default method for the geometry optimization. The results of the two completely different calculations agree quite well, which supports our confidence in the results of our C stack calculation. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Accurate prediction of heats of formation by a combined method of B3LYP and neural network correction

Recently, we proposed the X1 method which combines the B3LYP/6‐311+G(3df,2p)//B3LYP/6‐311+G(d,p) method with a neural network correction for an accurate yet efficient prediction of heats of formation (Wu and Xu, J Chem Phys 2007, 127, 214105). In this contribution, we discuss in detail how to set up the X1 neural network. We give examples, showing how to apply the X1 method and how the applicability of X1 can be extended. The overall mean absolute deviation of the X1 method from experiment for the 488 heats of formation is 1.52 kcal/mol compared with 9.44 kcal/mol for the original B3LYP results. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009     

Correlation corrected band structures of homopolypeptides v. B3LYP band structures of 19 homopolypeptides

Ab initio B3LYP crystal orbital (CO) calculations have been performed on the 19 homopolypeptides (PolyGly, PolyAla, PolySer, PolyThre, PolyLeu, PolyiLeu, PolyVal, PolyAspAc, PolyAsp, PolyGlutAc, PolyGlut, PolyHist, PolyProl, PolyCyst, PolyMeth, PolyTyr, PolyPhenAla, PolyArg, and PolyLys) in their β pleated sheet conformation. Keeping the main chain conformation fixed as in PolyGly, the side chain geometries were optimized. For the calculation 2n+1 different k points were used with n = 8 for the case of simpler and n = 10 for more complicated side chains. The basis set applied was the double ζ one of Clementi. According to the results obtained, the conduction bands are shifted upward and the valance band downward, compared with the results of previous BLYP 1 and LDA 7 CO calculations. The bandwidths are similar to the previous cases. The band edges are in many cases not at the endpoints of the first Brillouin zones, causing nonmonotonous dispersion of both the conduction bands (CB) and the valance bands (VB), respectively. The fundamental gap values due to the upward shifts of the CB and downward shifts of the VB are substantially larger than in the case of our previous DFT CO calculations (values 6.0–7.0 eV). They are very close to the gap values, which can be estimated on the basis of experimental ultraviolet (UV) spectra of some homopolypeptides and on the basis of intermediate exciton theoretical calculations (6.5–7.5 eV). These surprisingly good results for the gaps are due to the compensation of errors (LDA or BLYP gives too small and simple HF provides too large gap values) in the B3LYP method. The admixture of the exact HF exchange with a weight of 0.19 obviously compensates the self interaction error occurring in the LDA or BLYP methods. This article discusses whether/how this result could be established by other B3LYP CO calculations on simple polymer chains and on stacked systems (e.g., nucleotide base stacks). Furthermore, a comparative analysis of the ground state DFT methods, the HF method and of the optimized effective potential method could throw more light on our successful theoretical results for the gaps of the homopolypeptides. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

结合神经网络方法和扩大训练基组构建新B3LYP泛函

神经网络方法成功地应用于修正密度泛函理论B3LYP方法中的三个参数(a0、ax和ac)以构建新B3LYP交换相关泛函.本文采用包含输入层、隐藏层和输出层的三层式神经网络结构.总电子数、多重度、偶极矩、动能、四极矩和零点能被选为物理描述符.296个能量数据被随机地分成两组,246个能量数据作为训练集以确定神经网络的最优结构和最优突触权重,50个能量数据作为测试集以测试神经网络的预测能力.修正后的三个参数觔0、觔x、觔c从输出层处得到,并用于计算体系的热化学性质如原子化能(AE)、电离势(IP)、质子亲合能(PA)、总原子能(TAE)和标准生成热(ΔfH苓).修正后的计算结果优于传统B3LYP/6-311+G(3df,2p)方法的计算结果.经过神经网络修正后,296个物种的总体均方根偏差从41.0 kJ.mol-1减少到14.2 kJ.mol-1.     

Theoretical study of spectroscopic constants and molecular properties of diatomic anions using B3LYP method

Structure, spectroscopic constants and molecular properties of selected diatomic anions in their ground states have been studied in detail using HF/DF B3LYP method. The consistency of the calculated values of spectroscopic constants and molecular properties has been tested using four basis sets with improved quality. The spectroscopic constants and molecular properties of these diatomic ions agree well with the experimental and theoretical values wherever available. Most of the spectroscopic constants and molecular properties of these ions, in particular the spectroscopic constants of SiO⁻, CS⁻ and the molecular properties of SiN⁻, CP⁻, SiO⁻ are first reported.     

B3LYP,BLYP and PBE DFT band structures of the nucleotide base stacks

DFT crystal orbital (band structure) calculations have been performed for the nucleotide base stacks of cytosine, thymine, adenine, and guanine arranged in DNA B geometry. The band structures obtained with PBE, BLYP, and B3LYP functionals are presented and compared to other related experimental and theoretical results. The influence of the quality of the basis set on the fundamental gap values was also investigated using Clementi's double ζ, 6‐31G and 6‐31G* basis sets. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Assessment of the OLYP and O3LYP density functionals for first-row transition metals

We have investigated the performance of the OLYP and O3LYP density functionals for predicting atomic excitation energies and ionization potentials, and bond dissociation energies, geometries, and vibrational frequencies for selected first-row transition metal compounds, including hydrides (MH) and singly charged methylene and methyl cations. The OLYP and O3LYP functionals are similar to the well-known BLYP and B3LYP functionals, respectively, but use a new optimized exchange functional (OPTX) developed by Handy and Cohen (Mol Phys 2001, 99, 403) in place of the standard B88 exchange. A previous study by us on organic reactions (J Chem Phys 2002, 117, 1331) indicated that both OLYP and O3LYP gave results for heats of reaction and barrier heights that were overall superior to those using the popular B3LYP functional. For transition metals, however, although OLYP is overall superior to BLYP for molecular calculations, it is inferior to B3LYP. O3LYP provides results for molecules of about the same quality as B3LYP. For atomic excitation and 4s ionization energies, unless relativistic effects are included, OLYP and O3LYP are clearly worse than both BLYP and B3LYP. There is thus no real incentive to use either OLYP or O3LYP in place of B3LYP for calculations involving first-row transition metals.