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.

DFT Study on the Thermodynamic Properties of Polychloridized Phenoxazines

Fully optimized calculation and frequency analysis of 135 polychloridized phenoxazine (PCPX) compounds derivatives were carried out by using a DFT method at the B3LYP/6-31G* level and their thermodynamic parameters were obtained. The isodemic reactions were designed to calculate standard enthalpy of formation (ΔfH ) and standard free energy of formation (Δf ) of the PCPX congeners. The relation of these thermodynamic parameters with the number and the position of Cl atom substitution (NPCS) was studied, and it was found that there existed high correlation between of thermal correction to heat capacity at constant volume, entropy ( ), standard enthalpy of formation (Δf ) and or standard free energy of (CVө)formation (Δf ) and with NPCS. The order of relative stability of the PCPX congeners was theoretically proposed based on the relative magnitude of their Δf . The values of Cp,m were calculated by using statistical thermodynamics calculation Program program at the temperatures between( 200 to and 1800) K based on Gaussian 03 output files, and a obtained relative equation between the Cp,m and temperature was obtained by the least square method, found finding that the Cp,m has and T、T-1、T-2 have a very good relationship with T, T－1, and T－2.