【作者】 王桂香；

【导师】 肖鹤鸣； 潘仁明；

【作者基本信息】 南京理工大学 ， 材料学， 2008， 博士

【摘要】 运用量子力学（QM）和分子力学（MM）等理论和计算化学方法,对多系列高能化合物的结构和性能进行了较为系统的计算研究。特别注重潜在的高能量密度化合物HEDC的寻求和安全性评估,以满足航天、国防和国民经济相关发展的需要。本论文大体包括三部分内容:第一部分研究多系列芳烃化合物的结构和性能,兼顾HEDC的“分子设计”。在第一性原理DFT-B3LYP/6-31G^*水平上求得苯和苯胺类硝基衍生物的全优化几何构型、红外光谱（IR）及其归属,求得298～800K的热力学性质(C⁰_p,m、S⁰_m和H⁰_m)及其与硝基、氨基数和温度的关系;按0.001e·Bohr^-3电子密度曲面所包含的体积求得分子理论密度（ρ）;按Kamlet-Jacobs方程估算爆速（D）和爆压（P）。运用UHF-PM3方法求得该系列化合物的热解活化能（E_a）,并以UB3LYP/6-31G^*方法求得三种可能热解引发步骤的键离解能（BDE）,预测热解引发机理为C-NO₂键均裂并以此判别相对感度大小和稳定性。发现静态电子结构参数(C-NO₂键Mulliken键级M_C-NO2和硝基上净电荷Q_-NO2)之间、动力学参数(BDE_C-NO2和E_a)之间以及该二类参数之间,均存在良好的线性关系,表明它们可平行或等价地用于判别同系物的稳定性和感度相对大小。对照我们研究小组建议的判别HEDC能量与稳定性的定量标准(密度ρ≈1.9g·cm^-3、爆速D≈9.0km·s^-1、爆压P≈40Gpa和引发键离解能BDE≈80～120kJ·mol^-1),发现五硝基苯、六硝基苯和五硝基苯胺符合HEDC要求。而DATB尤其是TATB（1,3,5-Triamino-2,4,6-trinitrobenzene）,虽不是HEDC,但具有作为高能钝感耐热炸药的微观结构。对苯酚类和甲苯类硝基衍生物的类似DFT-B3LYP/6-31G^*计算,求得分子几何、IR谱、热力学性质(C⁰_p,m、S⁰_m和H⁰_m)、理论密度、爆速和爆压以及各可能热解引发步骤的BDE;通过动力学计算比较研究,确定了苯酚类硝基衍生物的O-H上H转移异构化反应为其热解引发步骤,即O-H键断裂、H转移异构化优先于C-NO₂均裂:确定了甲苯类硝基衍生物的C-H上H转移异构化反应为该类化合物的热解引发步骤,亦即C-H键断裂、H转移异构化优先于C-NO₂均裂;综合考虑密度、爆轰特性并结合稳定性要求,确认五硝基苯酚和五硝基甲苯（PNT）是HEDC。第二部分对著名起爆药六硝基芪（HNS）和2,5-二苦基-1,3,4-噁二唑（DPO）的结构和性能进行了系统理论研究。在B3LYP/6-31G^*水平上,求得六硝基芪及其多取代基（-NO₂、-NH₂和-OH）衍生物的全优化分子几何,求得IR谱并作指认,求得298～800K的热力学性质(C⁰_p,m、S⁰_m和H⁰_m)及其与基团种类数目和温度的关系:预测它们的理论密度、爆速和爆压;以（U）B3LYP/6-31G^*方法求得七种可能的热解引发步骤的BDE,并参照键电子集居数,确认C-NO₂键是HNS的硝基和氨基衍生物的热解和起爆引发键,而HNS羟基衍生物则以分子中O-H的H转移异构化反应为其热解引发步骤。根据HEDC能量和稳定性定量标准,判别九硝基芪和十硝基芪符合HEDC的要求。研究表明,通过向HNS分子中引入-NO₂基可提高能量和密度,而引入-NH₂基则利于钝感、增加稳定性。基于DFT-B3LYP/6-31G^*类似研究,首次求得DPO的全优化分子构型（属C₂点群）,求得并解析IR谱,预示其298～800K的热力学性质(C⁰_p,m、S⁰_m和H⁰_m)及其与温度的关系,求得分子理论密度、爆速和爆压;以（U）B3LYP/6-31G^*方法求得四种可能热解引发步骤的BDE,认为其热解或起爆可能是由均裂C-O、C-NO₂或N-N键而引发。由计算推测,在DPO中引进-NO₂基,可提高其ρ、D、P值直至符合HEDC标准。运用分子力学（MM）方法在Compass和Dreiding两种力场中,对DPO在七种最可几空间群（P21/c、P-1、P212121、P21、Pbca、C2/c和Pna21）中进行最佳分子堆积方式搜索,预测出其合理晶型属P212121空间群;运用DFT-GGA-RPBE方法,对该晶型进行周期性能带结构计算,从其态密度（DOS）和局域态密度（PDOS）分析,并考虑其带隙（△E_g=1.33 eV）值,可预示N-N、C-O和C-NO₂键可能是热解和起爆的引发键,预测DPO导电性较好,感度较大,确实适合作起爆药使用。第三部分运用线性回归方法建立关于感度的定量构效关系（QSAR）。对57种硝胺和硝基芳烃类高能化合物进行DFT-B3LYP/6-31G^*水平的计算研究。求得它们的全优化几何、电子结构;预测它们的理论密度、爆速和爆压;发现电子结构参数、爆速（D）、爆压（P）与静电感度(E_ES)之间存在的定性或定量关系。对含-CH₂N（NO₂）-的硝胺（如ORDX、AcAn和HMX等）或对称性较高但不含-CH₂N（NO₂）-结构的环杂硝胺（如DNDC和TNAD）,静电感度随爆速和爆压的增大而线性地增强,求得其线性关系式分别为:E_ES=-0.492 D²+42.68,R=0.957;E_ES=-62.97011gP+100.903,R=0.955。对硝基芳烃类化合物则分类进行研究,并获得如下定量关系:第一类是包括芳烃硫化物的CHNO类（其中N、O由-NO₂提供）:线性关系式为E_ES=-0.246D²+20.465,R=0.861;E_ES=-0.489p+18.891,R=0.866。第二类分子中含与硝基相邻的-CH₃或-CH₂CH₂-基团:线性关系式为E_ES=-0.984D²+60.101,R=0.998;E_ES=-1.748P+48.103,R=0.998。第三类分子中含-NH₂、-OH、-N=N-和-NH-等基团:线性关系式为E_ES=-0.520D²+41.488,R=0.963;E_ES=-0.925P+35.170,R=0.966。由此表明,从较易估算的爆轰性质（D或P）可定性判别或定量预示难于求得的静电感度。总之,本文对多系列高能化合物的结构-性能关系进行了系统的计算研究和分子设计,解释了大量已有实验事实,预示了许多未知的结果,提供了丰富信息和规律、利于指导实验合成,既能减少盲目实验造成的浪费,又能缩短实验周期和增强安全性,从而很好地完成了国家“973”和国家自然科学基金项目赋予的各项任务。更多还原

【Abstract】 The dissertation is devoted to systematic researches on the structures and properties of several series of energetic compounds and well-known high energy density compounds（HEDC）,using modern theoretical and computational chemistry methods,such as quantum mechanics（QM）and molecular mechanics（MM）.The whole work can be divided into three parts:The first part concentrates on the theoretical studies on the structures and properties of series of arenes,and at the same time considers the "molecular design" of HEDC.The fully optimized structures,assigned infrared（IR）spectra,and thermodynamic properties(C_p,m⁰,S_m⁰ and H_m⁰)related with the number of nitro and amino groups as well as the temperature in 200～800 K of two types of nitro derivatives of benzene and aminobenzenes are obtained at the DFT-B3LYP/6-31G^* level.According to the volume inside a contour of 0.001e/Bohr³,the molecular theoretical density（ρ）is evaluated,and detonation velocity（D）and detonation pressure（P）are estimated according to the Kamlet-Jacobs equation.The UHF-PM3 method is employed to evaluate thermolysis activation energies（E_a）.Bond dissociation energies（BDEs）of three possible trigger bonds in their thermolysis are computed by the B3LYP/6-31G^* method under the unrestricted model,and their pyrolysis mechanisms are ascertained to be the homolysis of C-NO₂ bond.It is found that,the static electronic structural parameters(the Mulliken bond population M_C-NO2 and the net charge of the nitro group Q_-NO2)and the kinetic parameters（BDE and E_a） are related with each other,which indicates that they all can parallelly or equivalently be used to identify the stability and the relative magnitude impact sensitivity for homologous energetic materials.Based on the QM calculations,the quantitative criteria of detonation performance as HEDCs（ρ≈1.9 g/cm³,D≈9.0 km/s,and P≈40.0 GPa）and the stability requirement（BDE of the initial step in thermolysis BDE≈80～120 kJ/mol） are employed to recommend several potential HEDC objectives from the title compounds.Pentanitrobenzene,hexanitrobenzene and pentanitroaniline agree with the forementioned criteria of HEDCs. The nitro derivatives of phenols and methylbenzenes have been studied similarly at the DFT-B3LYP/6-31G^* level.The fully optimized structures,IR,thermodynamic properties(C_p,m⁰,S_m⁰ and H_m⁰),theoretical molecular densityρ,detonation velocity D, detonation pressure P and BDEs of the possible trigger bonds in their thermolysis are obtained.Comparing the kinetic result,it is found that,for the nitro derivatives of phenols,their pyrolysis initiation is the isomerization reactions of the O-H bond,i.e., breaking of O-H bond followed by the isomerization reactions of the H transferring is prior to the homolysis of C-NO₂ bond,and for the nitro derivatives of methylbenzenes, their pyrolysis mechanism is the breaking of C-H bond followed by the H transferring. According to the quantitative criteria of HEDCs and stability demand, 2,3,4,5,6-pentanitrobenzenephenol and 2,3,4,5,6-pentanitrotoluene are potential candidates.The second part focuses on the theoretical studies on the structures and properties for the typical detonation-transferring explosives,such as the derivatives HNS（2,2’,4,4’,6,6’-hexanitrostilbene）and 2,5-dipicryl-1,3,4-oxadiazole（DPO）.For the derivatives of HNS substituted for nitro,amino and hydroxy groups,the fully optimized structures,assigned IR spectra,and thermodynamic properties(C_p,m⁰, S_m⁰ and H_m⁰)related with the various groups and the temperature in 200～800 K are obtained at the DFT-B3LYP/6-31G^* level.Theoretical densityρ,detonation velocity D,and detonation pressure P of each compound are predicted.BDEs of seven possible trigger bonds in their thermolysis are computed by the（U）B3LYP/6-31G^* method.Refering to the bond overlap populations,the homolysis is initiated from breaking the trigger linkage C-NO₂ bond for the nitro and amino derivatives of HNS, while for hydroxy derivatives it is started from breaking O-H bond followed by the isomerization reactions of the H transferring.Considering the energetic characteristic and the thermal stability,2,2’,3,3’,4,4’,5,6,6’-nonanitrostilbene and 2,2’,3,3’, 4,4’,5,5’,6,6’-decanitrostilbene essentially satisfy the quantitative criteria of HEDCs. The energy and density of HNS are improved when it is substituted by -NO₂ group. However,the substitution of -NH₂ group increases the insensitivity and stability of HNS.The fully optimized structures（C₂）,assigned IR spectra,and thermodynamic properties(C_p,m⁰,S_m⁰ and H_m⁰)related with the temperature in 200～800 K are obtained similarly at the DFT-B3LYP/6-31G^* level.Theoretical densityρ, detonation velocity D,and detonation pressure P are predicted.BDEs of four possible trigger bonds in their thermolysis are computed by the（U）B3LYP/6-31G^* method.The pyrolysis mechanism is found to be the homolysis of C-NO₂,N-N or C-O bond.It is presumed thatρ,D and P are probably improved so as to become HEDC when DPO is substituted by -NO₂ group.MM method is used to search for the most possible packing of DPO among the seven most possible space groups（P2₁/c,P-1,P2₁2₁2₁,P2₁,C2/c,Pbca and Pna2₁） with Dreiding and Compass force field,the reasonable crystal structures are predicted to pack in P2₁2₁2₁ space group.Periodic ab initio calculations are performed on the predicted crystal structure using the DFT-GGA-PBE method,and the density of states （DOS）,the partial density of states（PDOS）and the band gap（△Eg）are obtained, which indicates that the N-N,C-O or C-NO₂ bonds are possible trigger bonds and DPO is suitable to be used as a detonation-transferring explosive.The third part centers on establishing QSAR on sensitivity using linear regression method.The 57 nitramines and nitro arenes have been studied at the DFT-B3LYP/6-31G^* level.The fully optimized structures,theoretical densityρ,detonation velocity D,and detonation pressure P of each compound are predicted.It is found that,there are qualitative or quantitative relationships between the detonation velocity,pressure and electric sensitivity(E_ES).For the compounds with metylenenitramine units（-CH₂N（NO₂）-）in their molecules（such as ORDX,AcAn and HMX）or with the better symmetrical cyclic nitramines but without metylenenitramine units（such as DNDC and TNAD）,there is a linear relationship between the square of detonation velocity（D²）and electric spark sensitivity E_ES,and the equation are E_ES=-0.492 D²+42.68（R=0.957）and E_ES =-62.97011gP+100.903（R=0.955）.For nitro arenes,this series of compounds are classified and discussed and there are linear relationships between D² or P and E_ES.For the first type of compounds mainly belonging to C,H,N,O type explosives,whose N and O atoms are in the form of -NO₂ group,and including the aromatic sulfides,the formula are E_ES=-0.246 D²+20.465（R=0.861）and E_ES=-0.489P+18.891（R=0.866）;For the compounds with -CH₃ or -CH₂CH₂- groups whose ortho position have -NO₂ group,their linear relationships are E_ES=-0.984D²+60.101（R=0.998）and E_ES=-1.748P+48.103 （R=0.998）;For the compounds with -NH₂,-OH,-N=N- and -NH- groups in the molecules,their linear relationships are E_ES=-0.520D²+41.488（R=0.963）and E_ES =-0.925P+35.170（R=0.966）.Therefore,the more easily calculated detonation characteristics（D and P）can be used to theoretically predict or judge the magnitude of E_ESwhich is difficult to mensurate.In a word,the systemic theroretical studies on the structures and properties and the molecular design have been investigated for the energetic compounds,which explain a great deal of the experimental fact and predict many unknown results.The abundance of information and the rules provided are used to instruct the experimental synthesize,which not only decrease the waste that may be resulted from experiment, but also shorten the period of experiment and increase safety.The work of thesis has successfully completed the various tasks assigned by the projects of National 973 and National Nature Science Foundation of China.更多还原