Studies of Thermodynamic Properties and Relative Stability of Polybrominated Xanthones by Density Functional Theory

The thermodynamic properties of xanthone(XTH) and 135 polybrominated xanthones(PBXTHs) in the standard state have been calculated at the B3LYP/6-31G* level using Gaussian 03 program.The isodesmic reactions were designed to calculate the standard enthalpy of formation(△fHθ) and standard free energy of formation(△fGθ) of PBXTH congeners.The relations of these thermodynamic parameters with the number and position of Br atom substitution(NPBS) were discussed,and it was found that there exist high correlation between thermodynamic parameters(entropy(Sθ),△fHθ and △fGθ) and NPBS.According to the relative magnitude of their △fGθ,the relative stability order of PBXTH congeners was theoretically proposed.The relative rate constants of formation reactions of PBXTH congeners were calculated,Moreover,the values of molar heat capacity at constant pressure(Cp,m) from 200 to 1000 K for PBXTH congeners were also calculated,and the temperature dependence relation of them was obtained,suggesting very good relationships between Cp,m and temperature(T,T-1 and T-2) for almost all PBXTH congeners.     

DFT Study on the Thermodynamic Properties of Poly-bromine Carbazole

The molecular structures of 135 poly-bromine carbazole (PBCZs) compounds were fully optimized at the B3LYP/6-31G* level, and their thermodynamic properties at 98.15 K, 1.013 ×105 Pa were consequently obtained. Based on our isodesmic reaction, standard formation heat (ΔfH) and standard formation free energy (ΔfG) of PBCZs were calculated. Furthermore, the relationship between thermodynamic parameters and the position and number (NPBS) of Brsubstitution were also discussed. To our interest, a good dependence can be observed among entropy (S), ΔfH, ΔfG and NPBS. Ultimately, the theoretical stability order of isomers can be decided judging from the ΔfG value.     

二甲氧基嘧啶胺与金属配合物的恒容燃烧热测定

在无水乙醇中，使钴、铜、锌、锰的盐与二甲氧基嘧啶胺(AMP)反应，回流数 小时后，浓缩、冷却，抽滤，制得了6种二甲氧基嘧啶胺与钴、铜、锌、锰的固态 配合物．用化学分析和元素分析确定了它们的组成，分别为Co(AMP)_2Cl_2(1)， Cu(AMP)_2Cl_2(2)，Cu(AMP)_2(NO_3)_2(3)，Zn(AMP)_2Cl_2(4)，Mn(AMP) _2Cl_2(5)和zn(AMP)s04(6)；用IR，～1H NMR研究了他们的成键情况；用精密转动 弹热量计测定了配体及配合物的恒容燃烧热△_cU，计算了它们的标准摩尔燃烧焓 △_cH_m～θ和标准摩尔生成焓△fH_m～θ．     

估计聚合热与熵的原子团加和法

<正> 二十年来,Benson-Buss原子团加和法,已广泛用于低分子化合物的热力学参数估计.我们认为它也可以推广到高分子化合物,用来估计聚合热、聚合熵与聚合自由能等.本文推荐的经验估算法比文献估算方法有三个优点:简单直观;物理意义明确;不必引入任何另外的经验参数.     

Determination of combustion energies and the standard enthalpies of formation for the complexes of RE(Et_2dtc)_3(phen)

Solid complexes, RE(Et2dtc)3(phen) (RE=La, Pr, Nd, Sm-Lu), were synthesized with sodium diethyldithiocarbamate (NaEt2dtc3H2O),1,10-phenanthroline (o-phen·H2O) and hydrated lanthanide chlorides in absolute ethanol. The constant-volume combustion energies of complexes,ΔcU, were determined by a precise rotating-bomb calorimeter at 298.15 K. The standard enthalpies of combustion,ΔcHmθ, and standard enthalpies of formation,ΔfHmθ, were calculated for these complexes, respectively. The experiment results showed the "tripartite effect" of rare earth.     

Lu(Et2dtc)3(phen)的生成反应焓变、摩尔热容和恒容燃烧能测定

A ternary solid complex Lu(Et₂dtc)₃(phen) has been obtained from the reaction of hydrated lutetium chloride with sodium diethyldithiocarbamate (NaEt₂dtc), and 1,10-phenanthroline (o-phen·H₂O) in absolute ethanol. IR spectrum of the complex indicates that Lu³⁺ binds with sulfur atom in the Na(Et₂dtc)₃ and nitrogen atom in the o-phen. The enthalpy change of liquid-phase reaction of formation of the complex, Δ_rH_m^Ө (l), was determined to be (-32.821 ± 0.147 ) kJ·mol^-1 at 298.15 K by an RD-496 Ⅲ type heat conduction microcalormeter. The enthalpy change of the solid-phase reaction of formation of the complex, Δ_rH_m^Ө (s), was calculated to be (104.160 ± 0.168) kJ · mol^-1 on the basis of an appropriate thermochemistry cycle. The thermodynamics of liquid-phase reaction of formation of the complex was investigated by changing the temperature of liquid-phase reaction. Fundamental parameters, such as the activation enthalpy (ΔH_≠^Ө), the activation entropy (ΔS_≠^Ө), the activation free energy (ΔG_≠^Ө), the apparent reaction rate constant (k), the apparent activation energy (E), the pre-exponential constant (A) and the reaction order (n), were obtained by combination the reaction thermodynamic and kinetic equations with the data of thermokinetic experiments. The molar heat capacity of the complex, c_m, was determined to be (82.23 ± 1.47) J·mol^-1·K^-1 by the same microcalormeter. The constant-volume combustion energy of the complex, Δ_cU, was determined as (-17 898.228 ± 8.59) kJ·mol^-1 by an RBC-Ⅱtype rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, Δ_cH_m^Ө, and standard enthalpy of formation, Δ_fH_m^Ө, were calculated to be (-17 917.43 ± 8.11) kJ·mol^-1 and (-859.95 ±10.12) kJ·mol^-1, respectively.     

多氯10-氧吩噁噻系列化合物的热力学性质及稳定性的密度泛函理论方法研究

采用Gaussian 03程序中的密度泛函理论(DFT)方法,在BHandHLYP/6-311G**水平上对135个多氯10-氧吩噁噻系列化合物(PCPTO)进行了全优化和振动分析计算,得到了各分子在298.15K,1.013×105Pa标准状态下的热力学参数.设计等键反应,计算了PCPTO系列化合物的标准生成热(△fH)和标准生成自由能(△fG),同时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(S),△fH,△fG与NPCS之间有很强的相关性(R2≥0.991).根据△fG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PCPTO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,结果发现Cp,m与T,T-1和T-2之间有着很好的相关性(R2=1.000).     

ZnSO~4-Thr-H~2O体系(25℃)的相平衡及配合物的合 成与性质

用半微量相平衡方法研究了硫酸锌-苏氨酸-水体系在25℃及全浓度范围内的溶度性质,绘制了体系的相图和饱和溶液折光率曲线,体系中不存在新化合物。在水-丙酮混合溶剂中合成了未见文献报道的Zn(Thr)SO~4·H~2O三元固态化合物,通过化学分析、元素分析、IR,XRD,XPS和TG-DTG等对其组成、结构及热稳定性进行了研究。用精密转动弹热量计测定了配合物的标准燃烧能(-11848.76±17.76)J·g^-^1,求得它的标准燃烧焓(-3534.82±5.30)kJ·mol^-^1,标准生成焓(-256.37±5.69)kJ·mol^-^1.     

硝酸咪康唑与牛血清白蛋白作用的热力学特征研究

在模拟动物体生理条件和不同温度下,用荧光猝灭光谱、同步荧光光谱、三维荧光光谱和紫外可见吸收光谱等,研究了不同温度下硝酸咪康唑(Miconazole Nitrate,MIN)与牛血清白蛋白(BSA)相互作用的光谱行为。用Stern-Volmer方程、Lineweav-er-Burk双倒数方程和热力学方程等处理实验数据,得到在16～37℃温度范围内的作用常数KLB及热力学参数;发现MIN与BSA可结合形成具有一定结构的复合物,其荧光猝灭作用更符合静态猝灭作用特征,作用力可能主要是静电力;同时探讨了MIN对BSA构象的影响。为研究MIN的治病机制和生物学效应等提供了重要信息。     

铜(II)与四(间甲基)苯基卟啉镉(II)取代反应动力学

用分光光度法研究了二甲亚砜溶液中, 氯化铜与meso-四(间甲基)苯基卟啉镉(Ⅱ)(Cd(Ⅱ)P)亲电取代反应的动力学. 讨论了影响反应的因素, CuCl_2+Cd(Ⅱ)P→Cu(Ⅱ)P+CdCl_2提出了反应机理并进行了验证. 用AST286微机对实验数据进行非线性最小二乘法拟合, 得到拟合曲线及似平衡步的平衡常数K及其它基元步骤的速率常数k_1, k_(-1), k_2. 研究了温度对反应的影响, 求得似平衡步的△_rH_m~-θ-, △_rS_m~-θ-及其它基元步骤的活化参数△~≠H_m, △~≠S_m.     

量热法研究Cr3+水解聚合作用的热力学性质

水合多价金属离子在水溶液中发生水解聚合是一种普遍现象，铬（Ⅲ）离子就是这样的金属离子，具有水解聚合特征，铬（Ⅲ）的许多应用常与其水解特性有关［1］，虽然早在1907年Bjerrum［2］已经指出，但迄今为止，有关它的水解聚合的研究报道仍然较少［3］，而用微量热法研究Cr3十水解聚合作用的热力学还未见报道．Cr3＋水解聚合状态与其浓度有关，在低浓度和较高浓度下发现水解聚合产物不同．在较高浓度下形成单羟联的聚合质点，此观点曾相继由Hall［4］、戴安邦［5］等人提出并得到了验证．之后，戴安邦等人对Cr3＋的水解聚合作用进行了…     

反相高效液相色谱中溶质保留过程的热力学研究 Ⅱ. 焓变及其分量, 吸附及解吸附焓变

依据液相色谱中溶质计量置换保留模型, 从理论上分别推导出了在反相高效液相色谱(RP-HPLC)中lgI(与1mol溶质对固定相的亲合势有关的常数)和Z(对应于1mol溶质被固定相吸附时释放出置换剂的摩尔数)对绝对温度导数的线性关系式。发现非极性与极性小分子溶质的lgI和Z均具有热力学衡常数的特征。如在前报[1]报告的吉布斯自由能变一样, 也推导出了可将溶质保留过程中的总吸附焓变△H(Pa)分成两个独立的分量, 吸附焓变△(1,a)和解吸附焓变△H(Z,D)的表达式。可同时对在流动相中不同置换剂浓度条件下的△H(Pa)和△(Z,D)进行估算,并与实验值进行了比较, 偏差小于±10%。并用△H(1,a)和△H(Z,D)值对溶质在RP-HPLC的保留过程中热变化进行了解释。     

新型多氨-多酰氨配体和氨基酸的三元铜(Ⅱ)配合物(英)

合成3个多氨-多酰氨配体1，12-二((α-羟甲基)苯基)-2，5，8，11-四氮杂十二烷-1，12-二酮(L₁)，1，13-二((α-羟甲基)苯基)-2，5，9，12-四氮杂十三烷-1，13-二酮(L₂)，1，15-二((α-羟甲基)苯基)2，5，8，11，14-五氮杂十五烷-1，15-二酮（L₃）。利用pH滴定分别在5.0 ℃，15.0 ℃，25.0 ℃，35.0 ℃测定了铜(Ⅱ)与这3种配体在     

Theoretical Studies on the Molecular Structures and Thermodynamic Properties of Polychlorinated Fluorenes

Geometric structures of 135 polychlorinated fluorene (PCFR) molecules were optimized using density functional theory (DFT) at the B3LYP/6-311G** level and their thermodynamic properties in the ideal gas state were calculated. The relations of these thermodynamic properties with the number and position of chlorine atoms were also explored, from which the relative stability of PCFR congeners was theoretically proposed according to the magnitude of the relative standard Gibbs free energy of formation (Δr,fGθ). The results show that the geometric configuration of PCFR isomers is determined by the position of chlorine atoms. There exist two types of intramolecular weak interactions, i.e., C-H···Cl and Cl···Cl interactions in PCFR molecules. The change of ΔfHθ and ΔfGθ of most stable PCFR isomers with increasing the number of chlorine atoms is different from that in most unstable PCFR congeners. The values of ΔfHθ and ΔfGθ for PCFR isomers with the same number of chlorine atoms strongly depend on the position of chlorine atoms and the relative stability of PCFR congeners is mainly determined by intramolecular delocalized π bond and Cl···Cl nuclear repulsive interaction.     

用均根拓扑指数与路径数预测链烷烃的沸点和热力学性质

以距离矩阵为基础，建构调和均根拓扑指数（K），以表征链烷烃分子的大小 和分支情况，85种链烷烃的沸点(T_b)、标准生成焓(Δ_rH_m~θ)、标准熵(S_m~θ )、标准生成自由能(Δ_fG_m~θ)与K及路径数(P_2, P_3)的回归方程为: ln(793- T_b) = 6.48346-0.10092K + 0.00131P_2-0.01110P_3, R = 0.9996; -Δ_fH_m~θ = 62.664 + 25.331 K + 6.597 P_2 - 0.678 P_3, R = 0.9984; S_m~θ = 170. 691 + 67.425 K - 4.712P_2 + 5.251 P_3, R = 0.9989; Δ_fG_m~θ = -45.677 + 10.060 K + 0.555 P_2 + 2.342P_3, R = 0.9935。它们的计算值与相应实验值 都非常吻合。结果表明，K对链烷烃具有良好的结构选择性和性质相关性。     

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).     

三聚氰胺的生成焓、热容和熵

通过多种热化学方法研究了三聚氰胺的热力学性质. 首先用氧弹式燃烧热量计测定了三聚氰胺在298.15 K 时的燃烧热, 根据燃烧热结果, 计算出三聚氰胺的标准摩尔燃烧焓和标准摩尔生成焓, 分别为: △cHΘm=(-2455.17±4.65) kJ·mol-1; △fHΘm =(-763.38±5.16) kJ·mol-1. 然后根据键焓与燃烧焓之间的关系, 估算出三聚氰胺中的C≈N(此键介于单键与双键之间)键能为458.30 kJ·mol-1, 此值介于碳氮单键键能和双键键能之间. 通过绝热热量计测定了三聚氰胺从80到385 K的低温热容. 根据热容值, 计算了此温度区间的标准摩尔生成焓, 其与温度呈线性关系. 另外, 三聚氰胺的热稳定性也用热重-差示扫描量热(TG-DSC)法进行了分析, 确定其分解的DSC曲线的峰顶温度为603.37 K.     

一种精密恒温环境微量燃烧-溶解-反应多用量热计的设计及应用

将SRC-100型溶解-反应量热计改进成了一种精密恒温环境微量燃烧-溶解-反应多用量热计。采用电能法标定了量热计的能当量,其值为Ccalor=(987.63±0.61)J×K~(-1)。用该量热计分别测定了苯甲酸和丁二酸的标准质量燃烧热,分别为ΔcU~θ_(m,B)(cr,T=298.15 K)=-(26425.99±10.70)J?g~(-1)和Δ_cU~θ_(m,S)(cr,T=298.15 K)=-(12621.97±5.30)J?g~(-1)。测量的不确定度小于0.04%,精度高于0.05%。