几种咪唑-二氧杂环的含能取代衍生物的理论研究

使用DFT的B3LYP方法对几种咪唑二氧杂环化合物的分子结构、红外光谱、生成焓、爆轰性能和化学/热稳定性进行了研究.四种不同含能基团-NO₂,-NH₂,-N₃和-ONO₂对该化合物各项性能的影响进行了比较.结果表明-NO₂和-ONO₂基团有效地增加了化合物的密度,而-N³基团极大地增加了化合物的生成焓.其中-NO₂取代物爆轰性能接近1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane,-ONO₂取代物的爆轰性能低于hexahydro-1,3,5-trinitro-1,3,5-triazine.自然键轨道分析表明,这些化合物中相对较弱的键为取代基和咪唑环之间的键,以及二氧杂环中的C-O键.吸电子基团(-NO₂, -N³和-ONO₂)在分子中产生了明显的诱导效应,减弱了基团与咪唑环之间的链接,降低了对应键的键裂解能.研究表明基团的电负性与化合物的稳定性有关.考虑到化合物的爆轰性能和热稳定性,DNTNDI化合物满足高能量密度材料的要求.     

使用发射光谱对H2稀释情况下的感应耦合H2/C4F8等离子体中碳氟基团的研究

在射频输入功率为400W，气压为0.8Pa的条件下，使用光强标定的发射光谱方法研究了感应耦合H₂/C₄F₈等离子体中CF, CF₂, H和F基团的相对密度随流量比R=H₂/(H₂+C₄F₈)的变化情况，而HF基团相对密度的变化由四级质谱仪探测得到。结果表明等离子体活性先随着R的增加而升高，然后随着R的进一步增加而下降。在流量比从0逐渐上升到0.625的过程中，CF和CF₂基团的相对密度不断降低。实验中测得的CF基团的相对密度[CF]与理论计算得到的[CF]有很好的一致性说明了电子与CF2基团的碰撞反应是CF基团产生的主要原因。文中还讨论了HF基团。     

3-二甲氨基-2-甲基丙烯醛S2激发态结构动力学 (cited: 3)

采用共振拉曼光谱和完全活性自洽场理论计算研究了3-二甲氨基-2-甲基丙烯醛(DMAMP)光激发到S₂(ππ^*)态后的光物理性能．在B3LYP/6-311++G(d,p)水平计算确定了DMAMP与其三种异构体之间的基态异构化能垒,指认了振动光谱．采用涵盖紫外强吸收带的激光波长,获得了DMAMP在环己烷、乙腈和甲醇溶剂中的A-带共振拉曼光谱,含时密度泛函方法计算确定了该光谱中基频的相对强度,发现振动-电子耦合发生在S₂(ππ^*)态的Franck-Condon区域．CASSCF计算方法确定低单重和三重激发态、势能面锥形交叉点和系间窜跃点的激发能．共振拉曼光谱强度模式分析和CASSCF计算获得了DMAMP的A-带短时结构动力学和其后的衰变动力学表明,C1=O6和C2=C3之间的瞬时去共轭效应发生在S₂(ππ^*)态的Franck-Condon区域,激发态电荷重分布机制表明,C3和二甲氨基之间以及C1和C2之间的共轭增强效应发生在波包离开Franck-Condon区域后．C1=O6和C2=C3之间的去共轭效应使得-C3=N(CH₃)₂沿着C2-C3键旋转更加容易,C1-C2之间以及C3和N(CH₃)的共轭增强效应使得绕C1-C2和C3-N5旋转变得比较困难．这些表明DMAMP初始结构动力学沿着CI-1(S₂/S₀)交叉点展开,而沿CI-2(S₂/S₀)和CI-3(S₂/S₀)交叉点展开的几率可以忽略．提出了DMAMP分子受光激发从S_2,FC(ππ^*)经由各锥形交叉点和各系间窜跃点回到S₀或T_1,min的两个衰变通道.     

双(2,2-二硝基丙基)甲缩醛的结构和爆轰性能的量子化学研究

利用B3LYP/6-311+G(2d,p)方法对一种新型含能增塑剂双(2,2-二硝基丙基)甲缩醛进行几何优化,计算了其红外光谱、生成焓和爆轰特性. 分析了最弱键的键离解能和键级并预测了目标化合物的热稳定性. 结果表明双(2,2-二硝基丙基)甲缩醛中的四个N-NO₂键的键离解能都为164.38 kJ/mol. 表明目标化合物是一个热力学性能稳定的化合物. 以凝聚相生成焓和分子密度为基础,采用Kamlet-Jacobs方法预测其爆速和爆压. 目标化合物的晶体结构属于P21空间群.     

[Ru(MeIm)4L]2+ (L=iip, tip, 2ntz)的电子结构、DNA-键合、构效关系及光谱特征

采用密度泛函的方法,结合导体极化连续模型研究了水溶性二价钌-甲基咪唑类配合物[Ru(MeIm)₄iip]²⁺ (1)、[Ru(MeIm)₄tip]²⁺(2)和[Ru(MeIm)₄2ntz]²⁺ (3)的电子结构、DNA的键合倾向及构效关系．在水溶液中几何优化的基础上分析了配合物的电子结构特征,并合理解释了配合物与DNA的键合倾向．计算结果表明,在主配体上用噻吩代替咪唑取代基可以有效提高配合物与DNA的键合力;同时,在主配体的骨架上引入强电负性的N原子及NO₂基团可以明显降低配合物最低未占据分子轨道能量及前沿分子轨道能量差．基于以上计算结果,预测所设计的配合物3具有最大的DNA键合力常数．另外,详细分析了配合物1、2的构效关系及抗肿瘤作用机理,并预测了配合物3的抗肿瘤活性．最后,用含时密度泛函方法对配合物的电子吸收光谱进行了计算和模拟,并与实验结果进行了对比分析.     

用相互作用势指数估算单取代烷烃生成焓

基于直链烷烃生成焓的实验值提出16种取代基X(OH、SH、NH₂、Br、Cl、I、NO₂、CN、CHO、COOH、CH₃、CH=CH₂、C≡CH、Ph、COCH₃、COOCH₃)的相互作用势指数IPI(X). 用IPI(X)和极化效应指数建立模型,对单取代烷烃RX(包括含支链的化合物)的生成焓进行估算,所得回归方程有良好的相关性,该模型既考虑了基团R和X的贡献,又考虑了R与X相互作用的贡献. 并采用留一法对其稳定性和预测能力进行验证.     

(TPP)NO3的合成、表征与分子识别NO

在氯仿与无水乙醇的混合溶剂(体积比为1:1)中,四苯基卟啉(TPP)与Ce(NO₃)·6H₂O混合反应后,得产物Ce(TPP)NO₃. 通过紫外-可见光谱、红外光谱、荧光光谱、质谱、核磁共振氢谱的分析与表征,四苯基卟啉与铈原子以四齿方式进行配位,在同一个铈原子上还有一个硝酸根配位. 向Ce(TPP)NO₃的二氯甲烷溶液中通入NO气体,NO可以配位在同一个铈原子上,得到新的配合物Ce(TPP)(NO)NO₃,向此溶液中通入N₂,金属卟啉配合物可以恢复为配合物Ce(TPP)NO₃.     

Ligand Size Effect on PdLn Oxidative Addition with Aryl Bromide: A DFT Study

采用密度泛函理论的COSMO模型模拟了在DMF溶剂中三种不同体积的钯配体Pd(PR₃)_n (n=1,2) (PR₃=PH₃, PMe₃, PtBu₃)与溴苯氧化加成的反应过程. 对比双配体Pd(PR₃)₂的裂解能以及双配体钯Pd(PR₃)₂和单配体钯Pd(PR₃)氧化加成过程的能垒;结果表明,小体积的配体PH₃和PMe₃是以双配位的形式参加氧化加成过程的,而较大体积的配体PtBu₃是以单配位钯的形式参加氧化加成过程的.     

分子内旋转的阻碍势函数

根据分子的共同特征,将彼此紧密关联的分子,区别为三种基本类型,利用对称性分析方法,探求出这三类分子的内旋转势函数的一般公式。应用这些公式到具体分子时,能够非常简捷地写出它们的势函数表达式。利用第一类势函数分析具体问题时,算得的68个分子势垒数值,除少数外,所有计算结果与实验结果的差异均在实验误差范围之内。同时并发现当甲基上的C-H键换成C=C键时,作用能量大为减小;对于具有几个旋转轴的分子,隔开两个以上键间的作用能完全可以忽略。应用第二类势函数,具体联系了五类15个很重要的相关分子,即:CH₂Cl-CH₂Cl,CHCl₂-CHCl₂和CHCl₂-CH₂Cl;CH₂F-CH₂F,CHF₂-CHF₂和CHF₂-CH₂F;CCl₂F-CCl₂F,CClF₂-CClF₂和CClF₂-CCl₂F;CH₂(CH₃)-CH₂(CH₃),CH(CH₃)₂-CH(CH₃)₂和CH(CH₃)₂-CH₂(CH₃)以及C(CH₃)₂Cl-C(CH₃)₂Cl,C(CH₃)Cl₂-C(CH₃)Cl₂和C(CH₃)Cl₂-C(CH₃)₂Cl。理论上得到的结果和实验数据比较有满意的符合,对尚无实验涉及的某些分子的结与性构能,也在理论上作了一些预测。根据第三类势函数,探计了CClFH-CClFH与C(CH₃)ClH-C(CH₃)ClH两个分子的内旋转;从理论上推测了消式与活性式的内旋转异构体的数目及其构型。     

六硝基菧溶液的νs(NO2)激发及弛豫过程的相干反斯托克斯拉曼光谱

研究含能材料的振动激发和弛豫过程能深入理解含能材料的超快动态响应过程. 利用亚皮秒分辨的相干反斯托克斯拉曼(CARS)技术,实验直接观察基态的六硝基菧溶液中ν_s(NO₂)激发峰位于1385 cm^-1,弛豫时间为0.38和8.5 ps. 飞秒CARS实验观察到相应的拍频现象.     

Theoretical studies on structure and performance of [1,2,5]‐oxadiazolo‐[3,4‐d]‐pyridazine‐based derivatives

Based on energetic compound [1,2,5]‐oxadiazolo‐[3,4‐d]‐pyridazine, a series of functionalized derivatives were designed and first reported. Afterwards, the relationship between their structure and performance was systematically explored by density functional theory at B3LYP/6‐311 g (d, p) level. Results show that the bond dissociation energies of the weakest bond (N–O bond) vary from 157.530 to 189.411 kJ · mol^?1. The bond dissociation energies of these compounds are superior to that of HMX (N–NO_2, 154.905 kJ · mol^?1). In addition, H1, H2, H4, I2, I3, C1, C2, and D1 possess high density (1.818–1.997 g · cm^?3) and good detonation performance (detonation velocities, 8.29–9.46 km · s^?1; detonation pressures, 30.87–42.12 GPa), which may be potential explosives compared with RDX (8.81 km · s^?1, 34.47 GPa ) and HMX (9.19 km · s^?1, 38.45 GPa). Finally, allowing for the explosive performance and molecular stability, three compounds may be suggested as good potential candidates for high‐energy density materials. Copyright © 2016 John Wiley & Sons, Ltd.     

Comparative theoretical studies of high energetic cyclic nitramines

Density functional theory studies on cyclic nitramines were performed at B3LYP/6‐311G(d,p) level. The crystal structures were obtained by molecular packing calculations. Heats of formation (HOFs) were predicted through designed isodesmic reactions. Results indicate that the value of HOF relates to the number of =N–NO₂ group and aza nitrogen atom and increases with the augment of the number of =N–NO₂ group and aza nitrogen atom for cyclic nitramines. Detonation performance was evaluated by using the Kamlet–Jacobs equations based on the calculated densities and HOFs. All the cyclic nitramines exhibit better detonation performance than 1,3,5‐trinitro‐1,3,5‐triazacyclohexane and 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane. The stability of cyclic nitramines was investigated by the bond dissociation energies. The result shows that the increase of =N?NO₂ group or aza nitrogen atom reduces the stability of the title compounds. These results provide basic information for molecular design of novel high energetic density materials. Copyright © 2013 John Wiley & Sons, Ltd.     

Theoretical investigation of a series of bis(1H-tetrazol-5-yl)furazan and bis(1H-tetrazol) derivatives as high-energy-density materials

Using density functional theory (DFT), a series of bis(1H-tetrazol-5-yl)furazan and bis(1H-tetrazol) derivatives with different linkages and substituents are investigated theoretically as potential high-energy-density materials (HEDMs). The heat of formation (HOF), detonation properties, natural bond orbital (NBO) and thermal stabilities are calculated and reported. The introduction of a furazan ring, an –N=N– bridge group and an –N₃ substituent is beneficial to increase the HOF of the title compounds. NBO analysis shows that there are electronic delocalisation effects among the bridge groups, furazan and tetrazole rings, and substituted groups. The conjugation effects and electronic transitions are influenced by the different linkages and substituents. The estimated detonation velocities and pressures indicate that the –ONO₂ and –NO₂ groups and the –N=N– linkage play important roles in enhancing the detonation properties. The bond dissociation energy (BDE) calculations reveal that the –NO₂ group is the substituent group which causes the least thermal stability. The bond between the substituent group and the tetrazole ring is the weakest bond in the title molecules. Considering the detonation performance and the thermal stability, 17 compounds may be promising candidates for HEDMs with good performance. Eight of them (A3, A4, C3, C4, D3, F3, G1 and G3) have better detonation properties than HMX.     

Theoretical study of energetic trinitromethyl‐substituted tetrazole and tetrazine derivatives

Density functional theory method was used to study the heats of formation, energetic properties, and thermal stability for a series of trinitromethyl‐substituted tetrazole and tetrazine derivatives with different substituents. It is found that the group ―NO₂, ―NHNO₂, or ―NF₂ play a very important role in increasing the heats of formation of the derivatives. The calculated detonation velocities and pressures indicate that the group ―CF₂NF₂, ―NHNO₂, ―1H‐tetrazolyl, ―2H‐tetrazolyl, or ―1,2,4,5‐tetrazinyl is an effective structural unit for enhancing their detonation performance. An analysis of the bond dissociation energies for several relatively weak bonds indicates that incorporating the group ―NHNO₂ and ―NH₂ into parent ring decreases their thermal stability. Considering the detonation performance and thermal stability, 37 compounds may be considered as the potential high‐energy compounds. Their oxygen balances are close to zero. These results provide basic information for the molecular design of novel high‐energy compounds. Copyright © 2013 John Wiley & Sons, Ltd.     

DFT studies on a high-energy density cage compound 1, 3, 5, 7, 9, 11-hexo(N(CH3)NO2)-2, 4, 6, 8, 10, 12-hexaazatetracyclo[5, 5, 0, 0, 0] dodecane

The infrared and Raman spectra, heat of formation (HOF) and thermodynamic properties were investigated by B3LYP/6-31G^** method for a new designed polynitro cage compound 1,3,5,7,9,11-hexo(N(CH₃)NO₂)-2,4,6,8,10,12-hexaazatetracyclo[5,5,0,0,0]dodecane. The detonation velocity (D) and pressure (P) were predicted by the Kamlet–Jacobs equations based on the theoretical density and condensed HOF. The bond dissociation energies and bond orders for the weakest bonds were analysed to investigate the thermal stability of the title compound. The computational result shows that the detonation velocity and pressure of the title compound are superior to those of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), but inferior to those of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) and hexanitrohexaazaisowurtzitane (HNIW). And the analysis of thermal stability shows that the first step of pyrolysis is the rupture of the N₇–NO₂ bond. The crystal structure obtained by molecular mechanics belongs to the P2₁ space group, with the lattice parameters Z = 2, a = 11.8246 Å, b = 10.4632 Å, c = 15.9713 Å, ρ = 1.98 g cm^?3.     

Theoretical studies on 2‐(5‐amino‐3‐nitro‐1,2,4‐triazolyl)‐3,5‐dinitropyridine (PRAN) and its derivatives

In this work, a set of derivatives of 2‐(5‐amino‐3‐nitro‐1,2,4‐triazolyl)‐3,5‐dinitropyridine (PRAN) with different energetic substituents (?N₃, –NO₂, –NH₂, –NF₂) have been studied at the Becke, three‐parameter, Lee–Yang–Parr/aug‐cc‐pvdz, Becke, three‐parameter, Lee–Yang–Parr/6‐31G(d), Becke, three‐parameter, Perdew 86/6‐31G(d), and Becke three‐parameter, Perdew–Wang 91/6‐31G(d,p) levels of density functional theory. The gas‐phase heats of formation were predicted with isodesmic reactions and the condensed‐phase HOFs were estimated with the Politzer approach. The effects of different functionals and basis sets were analyzed. –N₃ and –NO₂ greatly increase while –NH₂ and –NF₂ slightly decrease heats of formation. An analysis of the bond dissociation energies and impact sensitivity shows that all compounds have good stability. The crystal densities (1.82–2.00 g/cm³) computed from molecular packing calculations are big for all compounds and that of the –NF₂ derivative is the largest. All derivatives have higher detonation velocity and detonation pressure than PRAN. Compounds 3 and 4 (R = NO₂ and NF₂) have better performance than hexahydro‐1,3,5‐trinitro‐1,3,5‐trizine and the performance of 4 is quite close to that of 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane, they are promising candidates of high energy compounds and worth further investigations. Copyright © 2012 John Wiley & Sons, Ltd.     

Theoretical insights on a series of difluoramino group–based energetic molecules

A series of difluoramino group–based energetic molecules was designed and the relative properties were investigated by density functional theory. The results show that all the designed molecules have high positive heat of formation which ranges from 479.48 to 724.02 kJ/mol, detonation velocity ranges from 8.01 to 11.26 km/s, detonation pressure ranges from 28.03 to 63.46 GPa, and impact sensitivity ranges from 18.2 to 54.5 cm. Then, compounds D2, D3, D5, E4, E5, E6, and F2 were selected as the potential high energy density materials based on detonation properties and sensitivities. Natural bond orbital charges, electronic density, frontier molecular orbital, electrostatic potential on the surface, and thermal dynamic parameters of the screened molecules (compounds D2, D3, D5, E4, E5, E6, and F2) were also predicted at B3LYP/6‐31G(d,p) level to give a better understanding on the chemical and physical properties of them.     

Computational design and screening of promising energetic materials: Novel azobis(tetrazoles) with ten catenated nitrogen atoms chain

Density functional theory methods were used to study on 2 N10 compounds, 1,1′‐azobis(tetrazole) and 1,1′‐azobis(5‐methyltetrazole). We systematically investigated 10 novel substituted azobis(tetrazoles) with 10 catenated nitrogen atoms and various energetic groups (–CF₃ 1 , –C(NO₂)₃ 3 , –N₃ 5 , –NH₂ 6 , –NHNH₂ 7 , –NHNO₂ 8 , –NO₂ 9 , –OCH₃ 10 , –OH 11 , –ONO₂ 12 ). The optimized geometry, frontier molecular orbitals, electrostatic potential, Infrared and nuclear magnetic resonance spectrum were calculated for inspecting the molecular structure and stability as well as chemical reactivity. The effects of different substituents on the density, enthalpy of formation, heat of explosion, detonation velocity and pressure, and sensitivity of the azobis(tetrazole) derivatives have been investigated. Compound 9 with nitro was found to have remarkable detonation performances (D = 9.61 km/s, P = 42.14 GPa), which are close to the excellent explosive CL‐20. Results show that compounds 1 , 3 , 4 , 7 , 9 , 11, and 12 have high potential to replace RDX. It is surprising that compounds 1 , 3 , 9, and 12 possess better energetic properties than HMX. These novel substituted azobis(tetrazoles) with unique N10 structure may be promising candidates of HEDMs with outstanding performance and acceptable sensitivities.     

Theoretical investigations of pyridine derivatives as potential high energy density materials

Density function theory has been employed to study pyridine derivatives at the B3LYP/6‐31 G(d,p) and B3P86/6‐31 G(d,p) levels. The crystal structures were obtained by molecular mechanics methods. The heats of formation (HOFs) were predicted based on the isodesmic reactions. Detonation performance was evaluated by using the Kamlet–Jacobs equations based on the calculated densities and HOFs. The thermal stability of the title compounds was investigated by the bond dissociation energies and the energy gaps (ΔE_LUMO?HOMO) predicted. It is found that there are good linear relationships between detonation velocity, detonation pressure, and the number of nitro group. The simulation results reveal that molecule G performs similar to the famous explosive HMX and molecule D outperforms HMX. According to the quantitative standard of energetics and stability as high energy density materials, molecule D essentially satisfies this requirement. These results provide basic information for molecular design of novel high energetic density materials. Copyright © 2012 John Wiley & Sons, Ltd.