多溴代二苯胺热力学性质的密度泛函理论研究

在B3LYP/6-31G*水平上对209个多溴代二苯胺(PBDPA)系列化合物进行了全优化和振动分析计算, 得到各分子在298.15 K, 101.3 kPa标准状态下的热力学参数. 设计等键反应, 计算了PBDPA系列化合物的标准生成热(ΔfHÖ)和标准生成自由能(ΔfGÖ). 研究了热力学参数SÖ与溴原子的取代位置及取代数目(NPBS)之间的关系, 结果表明: PBDPA系列化合物的SÖ, ΔfHÖ和ΔfGÖ与NPBS之间有很强的相关性(R2≥0.984). 根据异构体标准生成自由能的相对大小, 从理论上求得异构体的相对稳定性. 以Gaussian 03程序的输出文件为基础, 采用统计热力学程序计算了PBDPA化合物在200 K至1000 K的摩尔恒压热容(Cp,m), 并用最小二乘法求得Cp,m与温度之间的相关方程, 发现Cp,m与T, T－1和T－2之间有着很好的相关性(R2＝1.000).     

多溴代二苯硫醚系列化合物的热力学性质和稳定性的理论研究

在B3LYP/6-31G*水平上对209个多溴代二苯硫醚(PBDS)系列化合物进行了全优化和振动分析计算,得到各分子在298.15K,1.013×105Pa标准状态下的热力学参数.研究了热力学参数S与溴原子的取代位置及取代数目(NPBS)之间的关系,结果表明:S与NPBS之间有很强的相关性(R2=0.993).设计等键反应,计算了PBDS系列化合物的标准生成热(△fH)和标准生成自由能(△fG).根据异构体标准生成自由能的相对大小,从理论上求得异构体的相对稳定性.以Gaussian03程序的输出文件为基础,采用统计热力学程序计算了PBDS化合物在200至1000K的摩尔恒压热容(Cp,m),并用最小二乘法求得Cp,m与温度之间的相关方程,发现Cp,m与T,T-1和T-2之间有着很好的相关性(R2=1.000).     

多溴二苯并呋喃的热力学性质和稳定性的密度泛函理论研究

在B3LYP/6-31G*水平上对二苯并呋喃和135个多溴二苯并呋喃系列化合物(PBDF)进行了全优化计算和振动分析, 得到各分子的总能量(E_T)、焓(H⁰)、熵(S⁰)、自由能(G⁰)和恒容热容(C_V⁰), 研究了这些参数与溴原子的取代数目及取代位置的关系. 溴原子置换在不同位置时, 使E_T, H⁰和G⁰数值增加大小次序为: 1(9)＞3(7)＞2(8)＞4(6), 即置换在1(9)位最不稳定; 两个溴原子处在同一苯环时, E_T, H⁰和G⁰数值也都增加, 增加的顺序为: 邻>>间＞对, 即相互处于邻位最不稳定. 而且有两个溴原子同时取代在1和9位时, 使H⁰和G⁰的数值的增加比取代在邻位、间位和对位时的增加值都大. 每增加1个溴原子, S⁰增大约40.1 J•mol^－1•K^－1, C_V⁰增大约16.3 J•mol^－1•K^－1. 同时, 设计等键反应, 计算了各异构体的标准生成热(H_f⁰)和标准生成自由能(G_f⁰). 根据异构体自由能的相对大小, 从理论上求得异构体的相对稳定性顺序, 各异构体组中的稳定性顺序与PCDF系列的稳定性顺序基本一致.     

多溴吩噻嗪系列化合物的稳定性和热力学性质的密度泛函理论研究

用Gaussian 03程序, 在B3LYP/6-31G*水平上全优化计算了吩噻嗪和135个多溴吩噻嗪系列化合物(PBPTHs)在298.15 K和101.3 kPa状态时的热力学参数. 设计等键反应, 计算了PBPTHs系列化合物的标准生成热( )和标准生成自由能( ). 同时研究了这些参数与溴原子的取代位置及取代数目(NPBS)之间的关系. 结果表明: 多溴吩噻嗪的热能校正值(Eth)、恒容热容( )、标准熵( )、标准焓( )以及标准自由能( )与NPBS之间有很强的相关性(r2≥0.998). 在相关方程中, 溴原子的取代个数对多溴代吩噻嗪热力学数值的大小有很大影响. 根据 的相对大小, 从理论上求得异构体的相对稳定性顺序.     

多氯代菲分子结构和热力学性质的密度泛函理论研究

采用密度泛函理论方法在B3LYP/6-311G(d, p)水平上对527个多氯代菲分子的几何结构进行了全优化并计算得到它们的热力学性质(等容热容( )、熵(S$)、标准生成焓(ΔfH$)和标准生成Gibbs自由能(ΔfG$)), 研究了这些性质与取代的氯原子数目和位置的关系, 根据各异构体的相对标准生成Gibbs自由能(Δr,fG$)的大小, 得到它们的热力学稳定性顺序. 计算结果表明: 绝大多数多氯代菲分子具有非平面的几何构型, 在多氯代菲分子中存在三种类型的分子内弱相互作用(H…H、C—H…Cl和Cl…Cl相互作用), 随着分子中取代的氯原子数目的增加, 多氯代菲最稳定异构体的ΔfH$和ΔfG$开始时逐渐减小, 然后又快速增加. 具有相同数目氯原子的多氯代菲异构体的ΔfH$和ΔfG$与氯原子的取代位置有很大的关系. 多氯代菲异构体的相对热力学稳定性主要由分子内的离域π键和Cl…Cl核排斥作用的强弱决定.     

多氯代吩噁嗪热力学性质的密度泛函理论研究

在B3LYP/6-31G*水平上对135个多氯代吩噁嗪(PCPXs)系列化合物进行了全优化和振动分析计算, 得到各分子在298.15 K, 1.013×105 Pa标准状态下的热力学性质. 设计等键反应, 计算了PCPXs系列化合物的标准生成热(Δf )和标准生成自由能(Δf ), 研究了这些参数与氯原子的取代位置及取代数目(NPCS)之间的关系, 结果表明: 熵( )、Δf , Δf 与NPCS之间有很强的相关性. 根据异构体标准生成自由能的相对大小, 从理论上求得异构体的相对稳定性. 以Gaussian 03程序的输出文件为基础, 采用统计热力学程序计算了PCPXs化合物在200 K至1800 K的摩尔恒压热容(Cp,m), 并用最小二乘法求得Cp,m与温度之间的相关方程, 发现Cp,m与T, T－1和T－2之间有着很好的相关性.     

溴代作用对竹红菌素分子性质影响的理论研究

用AM1方法对红菌素（包插甲素和乙素）与它们的溴代物进行了量子化学对比计算,得到了生成热,前线轨道能级及偶极矩等,讨论了溴代作用对竹红菌素分子性质的影响。     

芴-硫芴共聚物的电子结构和光谱性质的理论研究

用DFT-B3LYP方法对低聚物(PF30T)_n [n(芴)∶n(硫芴)＝2∶1, 物质的量之比, n＝1～4], (PF50T)_n [n(芴)∶n(硫芴)＝1∶1, 物质的量之比, n＝1～4]体系全优化, 得到两系列低聚物的电离能(IP_(a,v))、电子亲和势(EA_(a,v))、空穴抽取能(HEP)、电子抽取能(EEP). 在此基础上用ZINDO和TD-DFT方法计算吸收光谱, 分析了两个系列的HOMO-LUMO能隙随着n递增的变化趋势及硫芴含量对低聚物电子结构和光谱性质的影响, 推断了高聚物的电子和光谱性质. 用ab initio CIS方法优化了低聚物的S₁激发态结构并分析了其与发射光谱的关系. 研究显示: 2,8位引入的硫芴基团, 破坏了链的共轭, 而且随着硫芴含量的增加, HOMO-LUMO能隙变大, 光谱蓝移; 激发态结构趋于共面化.     

多氟代、多氯代和多溴代二苯并对二噁英化合物的一些性质的比较研究

采用密度泛函理论(DFT)方法, 在B3LYP/6-311G**和B3LYP/6-31G*两种水平上, 对76种多氟代二苯并对二噁英系列化合物(PFDDs)进行了几何构型的全优化, 并计算了各分子在298.15 K, 1.013×10⁵ Pa的标准状态下的热力学参数. 基组从6-31G*增大到6-311G**没有显著改变标准生成热(Δ_fH^?)、标准生成自由能(Δ_fG^?)和标准熵(S^?)数值. 根据B3LYP/6-311G**水平计算得到的Δ_fG^?的相对大小, 求得PFDDs同数目取代氟原子的各异构体的相对稳定性的顺序. 采用基团贡献法计算了多溴代二苯并对二噁英(PBDDs)、多氯代二苯并对二噁英(PCDDs)和PFDDs的辛醇-水分配系数(lg K_ow). 并将PFDDs的Δ_fH^?, Δ_fG^?, S^?和lg K_ow的计算结果与PBDDs和PCDDs的相关数值进行了比较. 同时, 计算了PFDDs各组异构体化合物的生成反应相对速率常数, 采用统计热力学程序计算了这些化合物在200至1800 K的恒压摩尔热容(C_p,m), 并用最小二乘法求得C_p,m与温度之间的相关方程, 发现C_p,m与T, T^－1和T^－2之间有着很好的相关性.     

溴代环己烷发光性质的初探

溴代环己烷(BCH)本身不能发射荧光、燐光,而其乙醇溶液则可能发射较强的荧光.λ_ex/λ_em=273/302 nm,且在一定浓度范围内,浓度与荧光强度有良好线性关系,表现出BCH与醇间有一定的反应属性.另一方面,无论是BCH本身,或其甲、乙醇、CCl_4溶液,都能在βCD作用下,在所得悬浊液中,不经除氧操作直接诱导出一定强度的室温燐光,其主峰位λ_ex/λ_em=246/428 nm.与此相反,相同实验条件下,苯或溴苯却均无类似的βCD-RTP发射现象.     

Theoretical studies on the vibrational spectra, thermodynamic properties, detonation properties, and pyrolysis mechanisms for polynitroadamantanes

To look for high energy density materials (HEDM), the relationships between the structures and the performances of polynitroadamantanes (PNAs) were studied. The assigned infrared spectra of PNAs obtained at the density functional theory (DFT) B3LYP/6-31G level were used to compute the thermodynamic properties on the basis of the principle of statistical thermodynamics. The thermodynamic properties are linearly related with the number of nitro groups as well as with the temperatures. Detonation properties of PNAs were evaluated by using the Kamlet-Jacobs equation based on the calculated densities and heats of formation for titled compounds, and it is found that only when the number of nitro groups of PNA is equal to or more than eight can it be possible for PNAs to be used as HEDMs. The relative stabilities of PNAs were studied by the pyrolysis mechanism using the UHF-PM3 method. The homolysis of the C-NO2 bond is predicted to be the initial step of thermal decomposition. The activation energies (Ea) for the homolysis decrease with the number of nitro groups being increased on the whole. The stability order of dinitroadamantane isomers derived from the interactions among nitro groups is consistent with what is determined by Ea. The relations between the Ea's and the electronic structure parameters were discussed. In combination with the stability, PNA (1,2,3,4,5,6,7,8,9,10-) is recommended as the target of HEDM with insensitivity.     

A group-contribution correlation for predicting thermodynamic properties with the Perturbed-Soft-Chain Theory

The Perturbed-Soft-Chain theory (PSCT), an equation of state capable of predicting thermodynamic properties for a variety of compounds, is modified to be a group-contribution equation. The Group-PSCT (GPSCT) treats each pure compound as a sum of its constituent functional groups, and interactions among these groups are considered. The three pure-compound parameters, v*, T* and c, used in the original PSCT are calculated by using combining rules for five independent group parameters. The group parameters in this paper were determined from a correlation of the PSCT parameters.Using the GPSCT, calculated results show good agreement with experimental data. Liquid-densities and vapor pressures for twenty-six low molecular-weight compounds (alkanes, alkenes, and aromatics) have been calculated with average absolute errors less than 3.5% for liquid-densities and 7% for vapor-pressures. Though these values are somewhat larger than for the original PSCT, mixture predictions often are better for GPSCT than for PSCT, especially for mixtures involving polymers. This suggests that the GPSCT should prove useful for intermediate molecular weight (i.e., 200 – 1000) compounds for which little experimental data exists.     

Theoretical studies on the structures, thermodynamic properties, detonation properties, and pyrolysis mechanisms of spiro nitramines

Density function theory (DFT) has been employed to study the geometric and electronic structures of a series of spiro nitramines at the B3LYP/6-31G level. The calculated results agree reasonably with available experimental data. Thermodynamic properties derived from the infrared spectra on the basis of statistical thermodynamic principles are linearly correlated with the number of nitramine groups as well as the temperature. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the calculated densities and heats of formation. It is found that some compounds with the predicted densities of ca. 1.9 g/cm3, detonation velocities over 9 km/s, and detonation pressures of about 39 GPa (some even over 40 GPa) may be novel potential candidates of high energy density materials (HEDMs). Thermal stability and the pyrolysis mechanism of the title compounds were investigated by calculating the bond dissociation energies (BDE) at the B3LYP/6-31G level and the activation energies (E(a)) with the selected PM3 semiempirical molecular orbital (MO) based on the unrestricted Hartree-Fock model. The relationships between BDE, E(a), and the electronic structures of the spiro nitramines were discussed in detail. Thermal stabilities and decomposition mechanisms of the title compounds derived from the B3LYP/6-31G BDE and the UHF-PM3 E(a) are basically consistent. Considering the thermal stability, TNSHe (tetranitrotetraazaspirohexane), TNSH (tetranitrotetraazaspiroheptane), and TNSO (tetranitrotetraazaspirooctane) are recommended as the preferred candidates of HEDMs. These results may provide basic information for the molecular design of HEDMs.     

Synthesis and characterization of polybrominated fluorenes and their conversion to polyphenylated fluorenes and cyclopenta[def]triphenylene

We report the synthesis and characterization of polyphenylated fluorene derivatives and a ring cyclized product containing cyclopenta[def]triphenylene core. Polybromination on fluorene was achieved either by solid state reaction with bromine or utilizing Br₂/KBrO₃ in AcOH/H₂SO₄ mixture. The bromofluorenes were converted to the corresponding polyphenylated fluorenes by Suzuki coupling protocol. A hexabromofluorene underwent a multifold Suzuki coupling followed by C–H activation to produce a cyclopenta[def]triphenylene derivative. Fluorene ring showed a severe distortion from planarity beyond tetra-substitution which manifested in the optical properties.     

Theoretical studies on the structural,spectroscopic, thermodynamic,and electronic properties of zoledronic acid

The structure, spectroscopic, thermodynamic, and electronic properties of zoledronic acid (ZL, 1-hydroxy- 2-(1H-imidazol-1-yl)ethane-1,1-diyldiphosphonic acid), typical third-generation nitrogen-containing bisphosphonates (N-BPs), have been investigated systematically. Six conformations are taken into account, including three unprotonated and three protonated structures. They are optimized by four different density functional theory (DFT) methods combined with four different basis sets to evaluate their performance in predicting the structural and spectral features of ZL. Thermodynamic properties are calculated based on the harmonic vibrational analysis, including the standard heat capacity (C _p,m ⁰ ), entropy (S _m ⁰ ), and enthalpy (S _m ⁰ ). The ¹H and ¹³C NMR chemical shifts are calculated using the GIAO method and compared with the experimental data. Molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) analyses are also performed to study the electronic characteristics of the title compound.     

Theoretical studies on the structures, thermodynamic properties, detonation properties, and pyrolysis mechanisms of four trinitrate esters

Density function theory (DFT) has been employed to study the geometric and electronic structures of four trinitrate ester including nitroglycerin (NG), butanetriol trinitrate (BTTN), trimethanolethane trinitrate (TMETN) and trimethylolpropane trinitrate (TMPTN) at the B3LYP/6-31G^* level. Their IR spectra were obtained and assigned by vibrational analysis. Based on the frequencies scaled by 0.96 and the principle of statistic thermodynamics, the thermodynamic properties were evaluated, which were linearly related with the number of methylene groups as well as the temperature, obviously showing good group additivity. Detonation performances were evaluated by the Kamlet–Jacobs equations based on the calculated densities and heats of formation. It is found that density, detonation velocity, detonation pressure are decrease with the increase of the number methylene groups. Thermal stability and the pyrolysis mechanism of the title compounds were investigated by calculating the bond dissociation energies (BDE) at the B3LYP/6-31G^* level. For the nitrate esters, the ONO₂ bond is a trigger bond during thermolysis initiation process.     

Theoretical study on the thermodynamic properties and self-decomposition of methylbenzenediol isomers

Alkylated hydroxylated aromatics are major constituents of various types of fuels, including biomass and low-rank coal. In this study, thermochemical parameters are obtained for the various isomeric forms of methylbenzenediol isomers in terms of their enthalpies of formation, entropies, and heat capacities. Isodesmic work reactions are used in quantum chemical computations of the reaction enthalpies for O-H and H?C-H bond fissions and the formation of phenoxy- and benzyl-type radicals. A reaction potential energy on the singlet-state surface surface is mapped out for the unimolecular decomposition of the 3-methylbenzene-1,2-diol isomer. According to the calculated high pressure-limit reaction rate constants, concerted hydrogen molecule elimination from the methyl group and the hydroxyl group, in addition to intermolecular H migration from the hydroxyl group, dominates the unimolecular decomposition at low to intermediate temperatures (T ≤ 1200 K). At higher temperatures, O-H bond fission and concerted water elimination are expected to become the sole decomposition pathways.     

A new model for predicting thermodynamic properties of ternary metallic solution from binary components

A model has been derived to predict thermodynamic properties of ternary metallic systems from those of its three binaries. In the model, the excess Gibbs free energies and the interaction parameter ω₁₂₃ for three components of a ternary are expressed as a simple sum of those of the three sub-binaries, and the mole fractions of the components of the ternary are identical with the sub-binaries. This model is greatly simplified compared with the current symmetrical and asymmetrical models. It is able to overcome some shortcomings of the current models, such as the arrangement of the components in the Gibbs triangle, the conversion of mole fractions between ternary and corresponding binaries, and some necessary processes for optimizing the various parameters of these models. Two ternary systems, Mg–Cu–Ni and Cd–Bi–Pb are recalculated to demonstrate the validity and precision of the present model. The calculated results on the Mg–Cu–Ni system are better than those in the literature. New parameters in the Margules equations expressing the excess Gibbs free energies of three binary systems of the Cd–Bi–Pb ternary system are also given.     

全氟化合物热力学性质的密度泛函理论研究

用密度泛函理论B3LYP方法,在6-31G基组水平上,对12个全氟化合物分子进行了全优化计算,得到其分子零点振动能EZPV、热能校正值Eth、恒容热容CVΦ、标准熵SΦ以及配分函数lgQ等热力学参数,并计算了这些分子的电性拓扑状态指数Em.通过最佳变量子集回归建立了电性拓扑状态指数与热力学参数之间的QSPR模型,模型的相关系数R2分别为1.000,1.000,1.000,0.999和1.000,采用逐一剔除法得到的交叉验证相关系数R2cv分别为0.999,1.000,1.000,0.999和1.000,利用建构的数学模型得到热力学性质的相对平均误差分别为0.43%,0.41%,0.46%,0.41%和0.71%.从方程可以看出,F原子取代基数量是影响全氟化合物分子热力学参数大小的主要因素,检验证明所建模型具有良好的稳定性和预测能力.