顺反异构化对偶氮类含能化合物感度的影响

采用密度泛函理论的B3LYP/6-31G*方法优化了一些偶氮类含能化合物(偶氮苯衍生物、偶氮呋咱、偶氮三嗪和偶氮四嗪)的结构, 然后通过二阶微扰理论方法(MP2/6-31G*)进行单点能计算, 最后获得偶氮类含能化合物顺反异构体比较精确的相对能量. 结果发现, 偶氮类含能化合物的感度与其顺反异构体的相对能量有对应关系, 相对能量越大, 感度越低. 偶氮类含能化合物顺反异构体的相对能量可以作为评价其感度的指标之一. 通过分析偶氮类含能化合物顺反异构化过程对感度的影响机理, 提出偶氮类含能化合物具有自钝感特性.     

绿色环保型联四唑铋盐的合成及性能研究

本文以二氯乙二肟、二甲基甲酰胺(DMF)、叠氮化钠、盐酸羟胺和硝酸铋等为原料,合成了绿色环保型联四唑铋盐(Bi-BHT)。并且用Ozawa法和Kissinger法研究了其热分解动力学参数,结果表明Bi-BHT热分解峰温度为532.57 K,说明其热稳定性良好。此外,还得到了热分解的机理函数。并且通过GJB772A-97标准方法,研究了Bi-BHT的机械感度性能,研究表明Bi-BHT摩擦爆炸概率为20%,特性落高为125.9 cm,这表明其对机械撞击不敏感。     

含能配位聚合物[Cu(tza)2]n的晶体结构、热分析、感度和催化性能

以碱式碳酸铜和四氮唑乙酸在水中反应制备得到四唑乙酸铜(II)含能配位聚合物, 并培养出单晶. 运用元素分析, FT-IR分析和X-射线单晶衍射对标题配合物的组成和结构进行了全面的表征. 采用差示扫描量热分析(DSC)和热重-微分热重分析(TG-DTG)研究了标题配合物的热分解过程, 表明标题配合物的热分解主要包含三个放热峰. 用Kissinger和Ozawa-Doyle法对标题配合物的第一放热分解过程进行了动力学研究, 计算得到其活化能为356.1 kJ/mol. 对配合物的撞击、摩擦、火焰感度和5s爆发点测试表明该配合物具有一定的感度, 有望作为含能材料应用于相关领域. 同时研究了标题配合物对RDX热分解的影响, 结果表明: 标题配合物可以使RDX的放热分解峰的温度提前16.4 ℃,分解速度加快, 对RDX具有良好的催化作用.     

[Cu2Pt(npa)4X2](X=Cl-,NCS-)金属串配合物电子传输性质的研究

使用密度泛函理论(BP86)结合非平衡态格林函数(NEGF)方法研究金属串配合物[Cu₂Pt(npa)₄X₂] (X=Cl^-(1), NCS^-(2); npa=2-naphthyridylphenylamine)的电子结构和电子传输性质, 研究发现: (1)由于轴向配体NCS^-与Cu的结合比Cl^-的强, 使配合物1的Cu-Cu键比2的强而Cu-Pt键比2的弱, 故1的π^*_{Pt dxz/yz}轨道与π^*_Cu-Cu能级差ΔE比2小. (2) 1和2的传输通道均是β自旋的π^*轨道, 主要由π^*_Cu-Cu 和π^*_{Pt dxz/yz}轨道组合而成. ΔE越小π^*越离域, 传输能力越强. 在负偏压下和正偏压小于0.15 V时, 1的电流大于2; 但正偏压大于0.15 V后2的β电流显著高于1. (3) 2具有较好的整流效应. ΔE越大, Pt→Cu方向的传输越容易, 整流效应越强. 正偏压下2的电流显著大于负偏压下的电流, 0.15 V后2的整流比比1高10～40倍. (4)因ΔE_β< ΔE_α, α自旋通道传输能力小于β自旋的, 1和2具有良好的自旋过滤效应(高达80%～99%).     

1,3-二(炔丙基氧)苯与4,4'-二叠氮甲基联苯的聚合反应及聚合物性能的研究

研究了1,3-二(炔丙基氧)苯(BPOB)与4,4'-二叠氮甲基联苯(DAMBP)的本体聚合行为. 核磁共振氢谱(¹H NMR)表征了聚合物的结构, 通过傅立叶红外技术(FT-IR)观察了反应过程中的基团变化情况, 采用差示扫描量热技术(DSC)研究了聚合反应动力学, 在较低温度(80 ℃)下二元叠氮与二元炔发生了1,3-偶极环加成聚合反应, 生成了主链含三唑环的聚合物; 利用Kissinger法和Crane法处理得到了反应的动力学参数: 反应级数为0.92, 反应活化能E_a为79.8 kJ• mol^－1, 频率因子A为1.26×10¹⁰ min^－1. 利用凝胶渗透色谱(GPC)、动态热机械分析(DMA)和热重分析方法(TGA)研究了聚合产物的性能. 结果表明, 聚合物的数均分子量达4.22×10⁴, 聚合物有较高的玻璃化转变温度和良好的热稳定性, 玻璃化转变温度达到131 ℃, 热分解温度(T_d5)达355 ℃     

不同温度下HMX和RDX晶体的感度判别和力学性能预估分子动力学比较研究

为探讨和比较炸药黑索金(RDX)和奥克托今(HMX)晶体的结构、 能量和力学性质随温度的递变规律, 在COMPASS力场和NPT系综下, 对其合适的等原子数超晶胞模型分别进行5个温度(195, 245, 295, 345和395 K)下的分子动力学(MD)周期性模拟研究. 结果表明, 随着温度的升高, RDX和HMX晶体引发键N-NO₂的最大键长(L_max)的逐渐增大以及引发键连双原子作用能(E_N-N)和内聚能密度(CED)的逐渐减小均与感度随温度升高而增大的实验结果一致; 且在各温度下, RDX晶体的L_max均大于HMX晶体的L_max, 与HMX相比, RDX的E_N-N和CED均较小, 上述结果与RDX比HMX感度大的实验结果相符. 由此表明, 在一定条件下, L_max, E_N-N和CED可用于高能物质的热和撞击感度的相对大小的判别. 基于MD模拟原子运动轨迹, 用静态法求得2种晶体的弹性力学性能, 发现拉伸、 体积和剪切模量均随温度的升高而递减, 与实验结果一致.     

多孔纳米CoFe2O4的制备及其对高氯酸铵的热分解催化性能

采用胶晶模板法制备出具有三维多孔结构的纳米CoFe₂O₄。利用X射线衍射仪(XRD)、傅里叶变换红外(FT-IR)光谱仪、扫描电镜(SEM)、透射电镜(TEM)和N₂吸附-脱附对样品的晶型和形貌结构等进行表征,采用差示扫描量热法(DSC)对比研究多孔纳米CoFe₂O₄和球形纳米CoFe₂O₄对高氯酸铵(AP)的热分解性能的影响,并考察这两种催化剂对AP催化热分解的动力学参数。结果显示,制备出的多孔纳米CoFe₂O₄样品具有典型的尖晶石结构,孔径约200 nm;比表面积明显高于40 nm球形CoFe₂O₄,达到55.646 m²·g^-1。DSC测试结果表明：多孔纳米CoFe₂O₄的加入促进了AP的热分解,最高使AP的高温分解峰温降低91.46℃,能量释放最高达1120.88 J·g^-1,是纯AP分解放热量的2.3倍;多孔纳米CoFe₂O₄具有较高的比表面积,能提高催化反应的接触面积,使AP的高温分解峰温度更低,反应活化能较小,从而表现出比球形纳米CoFe₂O₄更高的催化活性。此外,对多孔纳米CoFe₂O₄催化AP的热分解机理进行初步探索,纳米多孔催化剂对气态中间产物的作用促进了AP的热分解。     

预氧化聚铝碳硅烷纤维的热分解动力学及其机理

利用热重分析仪(TGA)对预氧化聚铝碳硅烷(PACS)纤维进行了热动力学研究, 用改良的Coats-Redfern法计算了动力学参数, 用Doyle法计算了理论失重值, 并根据FT-IR, XRD和SEM对其热分解的机理进行了分析. 结果表明, 在热分解反应的主要阶段, 预氧化纤维的反应活化能低于PACS纤维, 氧的引入有利于纤维的热分解; 快速升温有利于预氧化PACS纤维的热分解. 在初始分解阶段, 主要为低分子量的PACS和H₂O的逸出, 同时≡Si—H键之间以及≡Si—H与≡Si—CH₃键发生了脱氢、脱CH₄反应, 从而导致交联程度的增加; 随热分解温度进一步的提高, 分子的有机侧基急剧热解, 分解产物从有机物转变为存在部分微晶的无机结构; 热分解温度继续提高, 纤维结构进一步完善, 1300 ℃左右, β-SiC晶粒大小约为2～4 nm左右, 纤维具有较好的性能.     

3，3′-偶氮-（6-氨基-1，2，4，5-四嗪）的合成及性能研究

以3,6-对(3,5-二甲基吡唑)-1,2,4,5-四嗪(BT)为起始物,经亲核取代、氧化脱氢、氨解和水解等四步反应,合成了高氮含能化合物3,3′-偶氮-(6-氨基-1,2,4,5-四嗪)(DAAT)。对DAAT的热分解性能进行了研究,由DSC、PDSC和TG-DTG技术获得了DAAT的热分解动力学参数和机理函数。结果表明,DAAT的热稳定性好,能量高。在5℃/min升温速率下,DAAT在283℃左右开始分解,放热峰值320℃,分解放热峰的分解焓为1974·33J/g,高于相同条件下硝胺系炸药HMX的分解焓;采用Kissinger法和Ozawa法求得其活化能分别为209·69和208·77kJ/mol;其热分解速率对压强比较敏感,且与环境压强成正比。采用VLWEOS对DAAT的爆轰性能进行了理论计算,结果表明将DAAT与传统含能材料混合,有望制备出高能钝感炸药。     

新型磷系阻燃剂1,3,5-三(5,5-二甲基-1,3-二氧杂-2-氧代己内磷酰基- 2-氧)苯的合成及热分解动力学研究

以新戊二醇、三氯氧磷及1,3,5-三羟基苯等为原料, 经过两步反应合成新型磷系阻燃剂1,3,5-三(5,5-二甲基-1,3-二氧杂-2-氧代己内磷酰基-2-氧)苯, 采用元素分析、FT-IR、MS及1H NMR等技术确定了标题化合物的分子结构. 以TG-DTG为手段, 研究该新型磷系阻燃剂在氮气气氛中的热分解动力学; 利用Kissinger法、Flynn-Wall-Ozawa (FWO)法对其进行热分解动力学研究, 求出该阻燃剂的热分解动力学参数; 利用Coast-Redfern法研究该阻燃剂的热分解机理. 结果表明, Kissinger法所求得的表观活化能为171.72 kJ&#8226;mol－1, 指前因子ln A为37.57; Flynn-Wall-Ozawa法所求得的表观活化能为172.05 kJ&#8226;mol－1. 标题化合物的热分解动力学方程g(α)＝α1/4, 反应级数n＝1/4.     

氢键酸度的量子化学参数表示

研究了137个化合物的总氢键酸度(∑A₂^H)与量子化学参数的相关性.对于含羟基或羧基化合物,∑A₂^H=-0.027⁷⁺3.826Q_H-0.0273E_LUMO-0.0654E_HOMO+3.085Q_O(n=70,r=0.982),其中Q_H表示羟基或羧基氢原子净电荷,E_LUMO表示最低未占据分子轨道能级,E_HOMO表示最高占据分子轨道能级,Q_O表示羟基或羧基中与氢原子连接的氧原子净电荷;对于含氨基化合物,∑A₂^H=-1.569+3.637Q_H-0.1235E_HOMO(n=49,r=0.985),其中Q_H表示氨基中较正氢原子的净电荷;对于含亚氨基化合物,∑A₂^H=-0.472+3.676Q_H(n=18,r=0.993),其中Q_H表示亚氨基氢原子的净电荷.     

Correlation analysis of substituent effects on the acidity of benzoic acids by the AM1 method

Theoretical analysis of the electronic effect of aromatic substituents was done with the use of the AM1 computational procedure. The gas-phase acidity of substituted benzoic acids was linear with the difference in the heat of formation between corresponding benzoic acids and benzoate anions, the energy of the highest occupied molecular orbital, and the net charge on the acidic oxygen atoms of the corresponding benzoate anions. The Hammett σ constant was linearly correlated with the net charge on the atoms of the acid moiety of substituted benzoic acids. The AM1 computational procedure satisfactorily reproduced the electronic properties of a wide variety of substituents.     

UV-vis, IR and 1H NMR spectroscopic studies of some mono- and bis-azo-compounds based on 2,7-dihydroxynaphthalene and aniline derivatives

The absorption spectra of mono- and bis-azo-derivatives obtained by coupling the diazonium salts of aromatic amines and 2,7-dihydroxynaphthalene have been studied in six organic solvents. The different absorption bands have been assigned and the effect of solvents on the charge transfer band is also discussed. The diagnostic IR spectral bands and 1H NMR signals are assigned and discussed in relation to molecular structure. Also, semi-empirical molecular orbital calculations using the atom superposition and electron delocalization molecular orbital (ASED-MO) theory have been performed to investigate the molecular and electronic structures of these compounds. According to these calculations, an intramolecular hydrogen bonding is essential for stabilization of such molecules.     

二苯二硫和二苄二硫润滑性能的量子化学研究

The molecular geometries optimization and electronic structures of diphenyl disulfide (DPDS) and dibenzyl disulfide (DBDS) compounds were investigated by density functional theory (DFT) and ab initio method at the 6-31G basis set level. The active atoms and bonds of reaction were provided by frontier molecular orbital theory. The molecular orbital parameters of DPDS and DBDS compounds and iron atom cluster were calculated by using density functional theory. The interaction pattern between the organic disulfide compounds and iron atom cluster was discussed based on the approximate rule of orbital energy. Some parameters characterizing the action strength between the organic disulfide compounds and iron atom cluster, including the bonding strength, reactive strength and static action strength, were analyzed by using frontier electron density, super de-localizability, net atomic charge and the interaction energy of chemical adsorption as criteria. The results indicate that S-S chemical bond and C-S chemical bond of the compounds are inclined to be broken when DPDS and DBDS interact with the metal. The anti wear ability order of DPDS and DBDS compounds is DPDS>DBDS, and the extreme pressure ability order of DPDS and DBDS compounds is DBDS>DPDS, and the prediction results based on quantum chemistry calculations are in good accordance with the friction and wear test results.     

Density functional and molecular orbital study of physical process of inversion of nitrogen trifluoride (NF3) molecule

The physical process of the umbrella inversion of the nitrogen trifluoride molecule has been studied invoking the formalisms of the density functional theory, the frontier orbital theory, and the molecular orbital theory. An intuitive structure and dynamics of evolution of the transition state for the event of inversion is suggested. The physical process of dynamic evolution of the molecular conformations between the equilibrium (C_3v) shape and the planar (D_3h) transition state has been followed by a number of molecular orbital and density functional parameters like the total energy, the eigenvalues of the frontier orbitals, the highest occupied molecular orbital and lowest unoccupied molecular orbital, the (HOMO–LUMO) gap, the global hardness and softness, and the chemical potential. The molecular conformations are generated by deforming the ∠FNF angle through steps of 2° from its equilibrium value, and the cycle is continued till the planar transition state is reached, and the geometry of each conformation is optimized with respect to the length of the N? F bond. The geometry optimization demonstrates that the structural evolution entails an associated slow decrease in the length of the N? F bond. The dipole moment at the equilibrium form is small and that at the transition state is zero and shows a strange behavior with the evolution of conformations. As the molecular structure begins to distort from its equilibrium shape by opening of the ∠FNF angle, the dipole moment starts increasing very sharply, and the trend continues very near to the transition state but abruptly vanishes at the transition state. A rationale of the strange variation of dipole moment as a function of evolution of conformations could be obtained in terms of quantum mechanical hybridization of the lone pair on the N atom. The pattern of charge density reorganization as a function of geometry evolution is a continuous depletion of charge from the F center and piling up of charge on the N center. The continuous shortening of bond length and the pattern of variation of net charge densities on atomic sites with evolution of molecular conformations predicts that the bond moment would decrease continuously. The quantum mechanical hybridization of the lone pair of the central N atom shows that the percentage of s character of the lone‐pair hybrid on the N atom decreases at a very accelerated rate, and the lone pair at the transition state is accommodated in a pure p orbital. The result of the continued destruction of asymmetry of charge distribution in the lone pair on the central N atom due to the elimination of contribution of the s orbital with evolution of molecular conformations is the sharp decrease in lone‐pair moment. The decrease in bond moment is overcompensated by the sharp fall of its offsetting component, the lone‐pair moment, resulting in a net gain in dipole moment with the evolution of molecular geometry. Since the offsetting component decreases very sharply, the net effect is a sharp rise of dipole moment with the evolution of molecular conformations just before the transition state. The lone‐pair moment is zero by virtue of the symmetry of the pure p orbital, the lone pair of the central atom in the transition state, and the sum of the bond moments is zero by symmetry of the geometry. The barrier height is quite high at ～65.45 kcal/mol, which is close to values computed through more sophisticated methods. It is argued that an earlier suggestion regarding the development of high barrier value of NF₃ system seems to be misleading and confronting with the conclusions of the density functional theory. An analysis and a comparative study of the physical components of the one‐ and two‐center energy terms reveals that the pattern of the charge density reorganization has the principal role in deciding the origin and the magnitude of barrier of inversion of the molecule and the barrier originates not from a particular energetic effect localized in a particular region of the molecule, rather the barrier originates from a subtle interplay of one‐ and two‐center components of the total energy. The decomposed energy components show that the F?F nonbonded interaction and N? F bonded interaction favor the formation of transition state, while the one‐center energy terms prohibit the formation of the transition state. The barrier principally develops from the one‐center energy components. The profile of the HOMO is isomorphic and that of the LUMO is homomorphic with the potential energy curve for the physical process of the event of umbrella inversion of the molecule. The variation of the HOMO–LUMO gap, ?ε, the global hardness, η, and the softness, S, as a function of the reaction coordinates of angular deformation of NF₃ molecule are quite consistent with the predictions of the molecular orbital and the density functional theories in connection with the deformation of molecular geometry. The profiles of ?ε, η, and S, as a function of reaction coordinates, mimic the potential energy curve of the molecule. The eigenvalues of the frontier orbitals, and the ?ε, η, S parameters are found to be equally effective theoretical parameters, like the total energy, to monitor the physical process of the inversion of pyramidal molecules. The nature of the variation of the global hardness parameter between the equilibrium shape and the transition state form for the inversion is in accordance with the principle of maximum hardness (PMH). © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2002     

A Quantum Chemistry Study of Inhibition Properties of Imidazole and Its Derivatives on Iron Surface Corrosion

The geometries of imidazole and its derivatives were respectively optimized by using ab initio method, and the molecular orbital energy levels and the charge densities were obtained for their optimum geometries. The frontier orbital energy levels, and the net charges of N (1) atom and the imidazole ring of those molecules were obtained with ab initio and SCC-DV-Xα methods. It was found that the inhibition properties of those compounds change with the highest occupied molecular orbital energy levels, and the net charges of N (1) atom. We took four iron atoms on the crystal plane (100) of α-iron as the surface which was used to study the adsorption towards the inhibitors. The adsorption models of the inhibitor to be adsorbed on the Fe-cluster surface were optimized with SCC-DV-Xα method. It turns out that the most favorable model is that the inhibitor molecule is adsorbed on the Fe-cluster surface in an inclined state. The calculation shows that the stabilization energies of the systems are well correlated with the inhibition efficiencies.     

N原子对取代NH_4H_2PO_4盐类晶体的二次谐波发生的影响(英文)

从N—H键在取代NH4H2 PO4盐的 [AH]4 [H2 PO4]类晶体中的突出作用出发 ,作者对几个 [AH]4 [H2 PO4]型晶体的二次谐波发生进行理论上的研究 (这里A =伯、仲、叔胺 )。并对这一类晶体的二次谐波发生和其亚结构单元 [AH]+ 中N原子上的净电荷之间的依赖关系进行了估计。     

新型均三氮苯类衍生物构效关系的模式识别研究

用量子化学密度泛函理论(DFT)、分子力学(MM)及模式识别方法,对34个新型均三氮苯类衍生物进行了结构活性关系研究.结果表明,影响此类衍生物分子除草活性的主要因素有C(1)上所带的电荷Qc(1),分子总能量E,分子生成热Ef,溶剂可及面积SGrid,分子体积V和C(3)上所带的电荷Qc(3)等参数.通过在C(1)上加上吸电子基,降低C(1)上的电荷,以及在C(3)上连接单取代氨基可以提高除草活性.所得模型对化合物生物活性有较好的预测效果.