扩展的距离矩阵指数W~*及其应用研究

重新定义了距离矩阵及距离矩阵拓扑指数W~*，该定义考虑分子中每一原子的 性质和成键情况以及分子中每一原子与所有其它原子的结合情况。拓扑指数W~*对 于饱和碳氢体系可还原为Wiener的距离矩阵指数W，同时，W~*还可一般地应用于含 多重键及杂质原子的有机体系和无机体系。本研究用W~*相关的卤代甲烷标准生成 焓、SiX_n（X = F，Cl，Br，I，n = 1～4）体系的标准生成焓，相关系数均在0. 99以上，置信度大于99.9%。并用W~*研究了含苯环的碳氢体系气相色谱保留指数， 含氧原子的醛酮体系的标准生成焓以及卤代苯体系的辛醇/水分配系数。对饱和碳 氢体，W为W~*的特殊形式。     

价电子轨道能量拓扑指数mZ及其应用

受Randic分子连接性拓扑指数^mZ的启发,本文构建了价电子轨道能量拓扑指数^mZ。用^mZ的0、1阶指数分别与无机氢化物的pKa1值、20种碱金属卤化物的晶格能U、生成焓△rHm、水化能△rG^0m和气态碱金属卤化物核间距R0关联,拟合的回归方程的相关系(指)数,满足优级或良级标准。预测取得较好的结果。     

半经验分子轨道法的电子密度拓扑分析（Ⅱ）

化学反应过程中的过渡态结构及氢键的拓扑性质,是近年来刚刚涉及的课题,本文讨论了文献[1]的方法对偏离平衡构型的过渡态结构及超分子体系的可用性问题及对计算精度较敏感的电子密度拉普拉斯量的拓扑特性。     

多阶F指数对碳氢化合物的QSPR研究

根据分子中原子与原子的不同邻接情况,重新定义了关联矩阵的矩阵元,并在此基础上定义了矩阵形式的多阶F指数 pF.多阶F指数 pF考虑了分子中每一顶点原子的特性及顶点原子与其它原子的多种相互作用.采用系列指数 pF中的F, 0F′, 1F′和 2F′对烷烃、烯烃、烷基苯共144个碳氢化合物的标准生成焓进行相关研究,相关系数均大于0.98,与卤化钛化合物TiXn (n=1～4, X=F, Cl, Br, I)的标准生成焓的相关系数也在0.99以上.     

拓扑指数F'与烷基苯标准生成焓相关关系研究

新建议的拓扑指数F'考虑了分子的图形特征,顶点原子的性质,顶点原子与相邻原子的键合情况,并以矩阵的形式把这些特征表达出来。n个原子构成的体系通过矩阵运算可得到包含n项的多项式,其中,每一项对应一个顶点原子对F'的贡献,从而赋予了拓扑指数F'明确的物理意义。用F'研究一些烷基苯的标准生成焓,得到了令人满意的结果。     

TATB与二氟甲烷以及与聚偏二氟乙烯的分子间相互作用

动用密度泛函理论(SFT)B3LYP方法,取3－21G*基组,求得TATB(1,3,5-三氨基-2,4,6-三硝基苯)与CH~2F~2混合体系的三种优化构型以Boys-Bernardi方案校正基组叠加误差求得结合能。在B3LYP/6----311G*//B3LYP/3---21G*水TATB与CH~2F~2间的最大结合能为4.62kJ·mol^-1,还用MO－PM3方法计算TATB与---（CF~2CH~2}－(N=1,2,3,4,5,)的混合体系,由色散校正电子相关近似地求得其结合能力。当n＝5时,求得TATB与－（CF~2CH~2）--~n的最大结合能约为52.97kJ·MOL^-1。此外,自然键轨道分析用于讨论TATB与CH~2F~2之间的电荷转移。     

呋喃分子链式加聚物(C_4H_4O)_n(n=1～8)的密度泛函理论研究

采用B3LYP/6-31G方法对呋喃分子链式加聚物(C4H4O)n(n=1~8)体系进行了全优化,在进行结构优化的同时得到链式加聚物的总能量(ET)、零点能(ZPE)、热容(opC)和熵(oS)。通过对体系的能量分析,确定得到的结构是体系的稳定构型;分析了ZPE、opC和oS与n的关系,并在能量的基础上得到呋喃分子以不同方式聚合成链式加聚物时的生成焓,并由此确定链式加聚物系列的聚合过程和相对稳定性。     

三聚氰胺和环三酮氢键复合物的理论研究

用AM1和PM3方法对三聚氰胺和环三酮衍生物的超分子复合物进行理论研究, 得到稳定化能和相对生成焓; 在AM1优化构型的基础上, 分别用INDO/SCI和AM1方法计算复合物的电子光谱和红外光谱. 结果表明, 两个单体通过氢键形成多聚体, 导致体系能量降低, 单体的电性和位阻差异能改变体系的稳定化能. LUMO-HOMO能隙的减小使电子光谱吸收峰发生红移, 氢键的形成削弱了单体原来的N-H键, 使红外振动频率变小.     

卤素与乙烯、取代乙烯的亲电加成反应的量子化学研究

用MNDO法及能量梯度法优化了F~+、Ci_+与乙烯、丙烯、氟乙烯亲电加成反反的中间体,得到最稳定的构型。结果表明,氯比氟容易生成环式中间体,取代的乙烯比不取代的更易生成开式中间体。用基于从头算(4-31G基组)的Morokuma方案分解以F~+为进攻试剂的三个体系的相互作用能。此反应中电荷迁移是最重要的相互作用,其次是静电相互作用。分析了上述两种取代基对相互作用能的影响。     

Al2P2^n-（n=1～4）簇几何构型和芳香性的理论研究

作为一个颇有争议的概念,芳香性一直是化学领域关注的课题．随着这一概念被成功引入无机分子及簇化学,芳香性研究再次成为讨论的热点．作者运用B3LYP和B3PW91两种方法,选择6-311＋G^＊基组,就Al2P2^n-（n=1～4）体系的稳定构型、电荷分布、芳香性等其他特性进行了理论计算及分析．结果显示,Al2P2^-,Al2P2^2-和Al2P2^3-分别具有三种稳定的构型,即平面、屋顶和链状结构;Al2P2^4-具有两种稳定的构型,即平面和屋顶结构．对于该体系而言,具有D2h对称性的异构体较稳定．     

不同环境介质中芘的三维荧光光谱研究

本文首次运用三维荧光光谱研究芘在不同环境介质中的荧光特性, 揭示芘的F3/F4反映的是环境有序性介质的形成, 而不是所处环境极性大小的一个量度,F1/F3才是其所处环境极性大小的一个量度, 结果显示芘的三维荧光光谱可以更好地对环境性质进行研究, 将进一步扩大芘的应用范围。     

Calorimetric and computational study of indanones

Condensed phase standard (p degrees = 0.1 MPa) molar enthalpies of formation for 1-indanone, 2-indanone, and 1,3-indandione were derived from the standard molar enthalpies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The standard molar enthalpies of sublimation for 1-indanone and 2-indanone, at T = 298.15 K, were measured both by correlation-gas chromatography and by Calvet microcalorimetry leading to a mean value for each compound. For 1,3-indandione, the standard molar enthalpy of sublimation was derived from the vapor pressure dependence on temperature. The following enthalpies of formation in gas phase, at T = 298.15 K, were then derived: 1-indanone, -64.0 +/- 3.8 kJ mol(-1); 2-indanone, -56.6 +/- 4.8 kJ mol(-1); 1,3-indandione, -165.0 +/- 2.6 kJ mol(-1). The vaporization and fusion enthalpies of the indanones studied are also reported. In addition, theoretical calculations using the density functional theory with the B3LYP and MPW1B95 energy functionals and the 6-311G** and cc-pVTZ basis sets have been performed for these molecules and the corresponding one-ring species to obtain the most stable geometries and to access their energetic stabilities.     

Effects of methyl substituent on the charge-transfer complexations of dicarbazolylalkanes with p-chloranil, tetracyanoethylene and tetracyanoquinodimethane

Series of 1,n-dicarbazolylalkanes and 1,n-di(3-methylcarbazolyl)alkanes (where n=1-5) were synthesized and the molar extinction coefficients, equilibrium constants, enthalpies, and entropies of their charge-transfer (CT) complexes with the π-acceptors p-chloranil, tetracyanoethylene, and tetracyanoquinodimethane were investigated. 1,n-Di(3-methylcarbazolyl)alkanes formed CT complexes with higher equilibrium constants, more negative enthalpies and entropies than 1,n-dicarbazolylalkanes. Vibrational spectra of CT complexes of one of the donor molecules (1,4-dicarbazolylbutane) with all three acceptors were compared.     

Computational study on the bond dissociation enthalpies in the enolic and ketonic forms of beta-diketones: their influence on metal-ligand bond enthalpies

A computational study on the thermodynamic properties of 13 beta-diketones is presented. The B3LYP//6-311+G(2d,2p)//B3LYP/6-31G(d) theoretical approach was employed to compute the O-H and C-H bond dissociation enthalpies and enthalpy of tautomerization and to estimate standard gas-phase enthalpies of formation for the radicals and for the parent molecules. The gas-phase enthalpies of formation for the neutral molecules are in excellent agreement with available experimental data, supporting the estimates made for the radicals. The latter are very important for the clarification of the thermochemistry of many beta-diketonato metal complexes previously reported in the literature. Importantly, when substituents R = -CHR' are attached to the beta-diketone's scaffold, C-H homolytic bond cleavage is always favored with respect to O-H bond scission.     

[Cu(C~1~2H~8N~2)(H~2O)(C~4H~4O~4)]·2H~2O的合成和晶 体结构

将适量邻菲啰啉、丁二酸和CuCl~2·2H~2o(摩尔比=1:1)溶于水和甲醇的混合溶剂[V(水):V(甲醇)=1:1]后,滴加NaOH溶液至pH=4.8。滤去沉淀物后,滤液于室温下缓慢蒸发得蓝色细长[Cu(C~1~2H~8N~2)(H~2O)(C~4H~4O~4)]·2H~2O晶体。晶体属三斜晶系,P1(No.2)空间群。晶胞参数a=0.7462(1)nm,b=(0.9959)1nm,c=1.2266(1)nm,α=75.02(1)°,β=82.38(1)°,γ=74.76(1)°,V=0.8475(2)nm^3,Z=2,D~c=1.622g·cm^3,F(000)=426.3882个独立衍射点中,2789个可观测点满足F~0^2≥2σ(F~0^2),R=0.0450,wR^2=0.0951。配合物内每个Cu与邻菲啰啉螯合配体中的2个N原子、来自不同羧酸根的2个羧基O和1个水分子O原子配位,形成扭曲的四方锥体,其中一羧基O位于锥顶[d(Cu－N)=0.2006(3),0.2032(3)nm;赤道d(Cu－O)=0.1972(2),0.1973(2)nm;轴向d(Cu－O)=0.2210(2)nm]。双齿桥联丁二酸根连接Cu原子形成平行于[100]方向的多聚超分子链^1~∞[Cu(phen)~2(H~2O)·(C~4H~4O~4)~2~/~2]~2。芳环堆积间距交替为0.366nm和0.380nm。未配位的H~2O分子位于超分子双链之间。     

Thermodynamic properties of quinoxaline-1,4-dioxide derivatives: a combined experimental and computational study

The mean (N-O) bond dissociation enthalpies were derived for three 2-methyl-3-(R)-quinoxaline 1,4-dioxide (1) derivatives, with R = methyl (1a), ethoxycarbonyl (1b), and benzyl (1c). The standard molar enthalpies of formation in the gaseous state at T = 298.15 K for the three 1 derivatives were determined from the enthalpies of combustion of the crystalline solids and their enthalpies of sublimation. In parallel, accurate density functional theory-based calculations were carried out in order to estimate the gas-phase enthalpies of formation for the corresponding quinoxaline derivatives. Also, theoretical calculations were used to obtain the first and second N-O dissociation enthalpies. These dissociation enthalpies are in excellent agreement with the experimental results herewith reported.     

一种新的结构参数用于卤化物的QSPR研究

基于邻接矩阵和原子特征值（ｔｉ）建立一种新的结构参数（＾１Ｑ），它对无机分子具有良好的区分能力，并且计算简单，＾１Ｑ用于ＡＸｋ（ｋ＝１，２，３，４）型卤化物的标准生成焓、晶格能、反应截面等物理化学性质的相关性研究，获得了优于文献方法的结果。     

Strength of the Zn-N coordination bond in zinc porphyrins on the basis of experimental thermochemistry

The compound, 5,10,15,20-tetrakis(4-methoxyphenyl)porphine zinc(II) (ZnTMPP), was prepared, and its thermochemical properties were experimentally established. The standard molar energy of combustion (Delta(c)U degrees m) was determined from oxygen rotating-bomb combustion calorimetry experiments. The standard molar enthalpies of combustion (Delta(c)H degrees m) and formation (Delta(f)H degrees m) were derived. The enthalpy of sublimation (Delta(cr)(g)H degrees m) was determined by Knudsen effusion at high temperatures. With these results, the standard molar enthalpies of formation and atomization (Delta(at)H degrees m) in the gas state were calculated. A summary of the results at T = 298.15 K (p degrees = 0.1 MPa) is shown in Table 1. Using these results and those previously obtained for the free ligand, 5,10,15,20-tetrakis(4-methoxyphenyl)porphine, the mean dissociation enthalpy for the Zn-N coordination bond is obtained as D(Zn-N) = (160 +/- 9) kJ.mol-1. This value is consistent with the results obtained using the same experimental approach in a similar system (5,10,15,20-tetraphenylporphine, TPP/ZnTPP) reported elsewhere. A discussion of the strength for the Zn-N coordination bond is made in terms of the structural and electronic features of the molecules involved.