Optimized calculations of 75 PCDDs and their parent DD were carded out at the B3LYP/6-31G＊ level by density functional theory （DFT） method. The structural parameters were obtained and significant correlation betwee...Optimized calculations of 75 PCDDs and their parent DD were carded out at the B3LYP/6-31G＊ level by density functional theory （DFT） method. The structural parameters were obtained and significant correlation between the C1 substitution position and some structural parameters was found. Consequently, the number of C1 substitution positions was taken as theoretical descriptors to establish two novel QSPR models for predicting lgKow and -lgSw of all PCDD congeners. The two models achieved in this work contain two variables （Na and Nβ）, of which r = 0.9312, 0.9965 and SD = 0.27, 0.12 respectively, and t values are all large. The variation inflation factors （VIF） of variables in the two models herein are both less than 5.0, suggesting high accuracy of the lgKow and -lgSw predicting models, and the results of cross-validation test also show that the two models exhibit optimum stability and good predictive power. By comparison, the correlation and predictive ability of the present work are more advantageous than those obtained using semi-empirical AM1 and GC-RI methods.展开更多
Optimized calculations of 209 polychlorinated diphenyl ethers （PCDEs） and diphenyl ethers were carried out at the B3LYP/6-31G^＊ level with the Gaussian 98 program. Based on the theoretical linear solvation energy r...Optimized calculations of 209 polychlorinated diphenyl ethers （PCDEs） and diphenyl ethers were carried out at the B3LYP/6-31G^＊ level with the Gaussian 98 program. Based on the theoretical linear solvation energy relationship （TLSER） model, the obtained structural parameters were taken as theoretical descriptors to establish the novel QSPR model for predicting aqueous solubility （-lgSw） of PCDEs. The model obtained in this work contains two variables： mean molecular polarizability （a） and the most positive partial charge on a hydrogen atom （qH^＋）, of which RE = 0.9606 and SD = 0.32. And the results of cross-validation test also show that the model exhibits optimum stability and better predictive power. Moreover, the predictive power of the new model is better than that of MCIs method.展开更多
Optimization calculations of 209 polychlorinated biphenyls （PCBs） were carried out at the B3LYP/6-31G^＊ level. It was found that there is significant correlation between the Cl substitution position and some struct...Optimization calculations of 209 polychlorinated biphenyls （PCBs） were carried out at the B3LYP/6-31G^＊ level. It was found that there is significant correlation between the Cl substitution position and some structural parameters. Consequently, Cl substitution positions were taken as theoretical descriptors to establish a novel QSPR model for predicting –lgSw of all PCB congeners. The model achieved in this work contains four variables, of which r^2 = 0.9527, q^2 = 0.9490 and SD = 0.25 with large t values. In addition, the variation inflation factors （VIFs） of variables in this model are all less than 5.0, suggesting high accuracy of the –lgSw predicting model. And the results of cross-validation test and method validation also show that the model exhibits optimum stability and better predictive capability than that from the AM1 method.展开更多
Structural parameters of 36 fluorobenzene, chlorobenzene and bromobenzene compounds were computed at the B3LYP/6-31G^＊ level with DFT method. Based on the experimental data of aqueous solubility （–lgSw） and n-octa...Structural parameters of 36 fluorobenzene, chlorobenzene and bromobenzene compounds were computed at the B3LYP/6-31G^＊ level with DFT method. Based on the experimental data of aqueous solubility （–lgSw） and n-octanol/water partition coefficient （lgKow）, using the modified theoretical linear solvation energy relation （MTLSER） model, correlation equations that can predict –lgSw and lgKow were developed using structural parameters as theoretical descriptors. The correlation coefficients （r） of these equations are 0.9728 and 0.9967, respectively. These equations were further validated by variance inflation factors （VIF） and t-test methods and then used to predict –lgSw and lgKow values. By comparison, the correlation and predictive ability of our work are more advantageous than those calculated from valence molecular connectivity indices method and molecular topology index method.展开更多
Optimized calculation of dibenzofuran （DF） and 135 polychlorinated dibenzofurans （PCDFs） was carried out at the B3LYP/6-31G＊ level in GAUSSIAN 98 program. Based on the theoretical linear solvation energy relation...Optimized calculation of dibenzofuran （DF） and 135 polychlorinated dibenzofurans （PCDFs） was carried out at the B3LYP/6-31G＊ level in GAUSSIAN 98 program. Based on the theoretical linear solvation energy relationship （TLSER） model, the obtained structural parameters were taken as theoretical descriptors to establish the novel quantitative structureproperty relationship （QSPR） model for predicting n-octanol/water partition coefficients （lgKow） of PCDFs. The new model of lgKow achieved in this work contains three variables： energy of the highest occupied molecular orbital （EHOMO）, the most negative atomic partial charge （q^-） and average molecular polarizability （a）, of which R^2= 0.9011 and SD = 0,17 with larger t values. In addition, the variation inflation factors （VIF） of variables in the present model are all less than 5.5, suggesting high accuracy of the lgKow model. And the results of cross-validation test （q^2 = 0.8688） and method validation also show this model exhibits optimum stability and better predictive power than semi-empirical method. At the same time, it is found that the aqueous solubility （-lgSw） has high relative correlation with constant volume molar heat capacity （Cv^0）, of which R^2 = 0.9777 and SD = 0.22. Moreover, lgKow and -lgSw values of all PCDF congeners were predicted respectively.展开更多
在高效液相色谱(HPLC)测定方法的基础上,采用摇瓶法,准确测得25℃时16个取代苯硫酚类化合物的水溶解度(-lgSw)和19个正辛醇/水分配系数(lgKow)数据.采用密度泛函理论(DFT)中的B3LYP方法,在6-311G**基组上全优化计算得到24个取代苯硫酚...在高效液相色谱(HPLC)测定方法的基础上,采用摇瓶法,准确测得25℃时16个取代苯硫酚类化合物的水溶解度(-lgSw)和19个正辛醇/水分配系数(lgKow)数据.采用密度泛函理论(DFT)中的B3LYP方法,在6-311G**基组上全优化计算得到24个取代苯硫酚的结构参数和热力学参数,采用SPSS12.0 for windows程序,分别求得-lgSw和lgKow值与这些参数之间的相关方程,相关系数R2分别为0.958和0.946.用交叉验证法对方程的稳定性进行了验证(q2分别为0.925和0.930),并用t检验和变异膨胀因子(Variance Inflation Factors,VIF)对两个方程中各变量的显著性和自相关性进行了检验.结果表明:所建方程具有较强的预测能力,并用其预测了8个没有实验数据的取代苯硫酚的-lgSw值和5个lgKow值.展开更多
基金This work was supported by the National Natural Science Foundation of China (No. 20737001)(2003CB415002)China Postdoctoral Science Foundation (No. 2003033486)
文摘Optimized calculations of 75 PCDDs and their parent DD were carded out at the B3LYP/6-31G＊ level by density functional theory （DFT） method. The structural parameters were obtained and significant correlation between the C1 substitution position and some structural parameters was found. Consequently, the number of C1 substitution positions was taken as theoretical descriptors to establish two novel QSPR models for predicting lgKow and -lgSw of all PCDD congeners. The two models achieved in this work contain two variables （Na and Nβ）, of which r = 0.9312, 0.9965 and SD = 0.27, 0.12 respectively, and t values are all large. The variation inflation factors （VIF） of variables in the two models herein are both less than 5.0, suggesting high accuracy of the lgKow and -lgSw predicting models, and the results of cross-validation test also show that the two models exhibit optimum stability and good predictive power. By comparison, the correlation and predictive ability of the present work are more advantageous than those obtained using semi-empirical AM1 and GC-RI methods.
基金funded by the 973 National Basic Research Program of China (2003CB415002)China Postdoctoral Science Foundation (No. 2003033486)
文摘Optimized calculations of 209 polychlorinated diphenyl ethers （PCDEs） and diphenyl ethers were carried out at the B3LYP/6-31G^＊ level with the Gaussian 98 program. Based on the theoretical linear solvation energy relationship （TLSER） model, the obtained structural parameters were taken as theoretical descriptors to establish the novel QSPR model for predicting aqueous solubility （-lgSw） of PCDEs. The model obtained in this work contains two variables： mean molecular polarizability （a） and the most positive partial charge on a hydrogen atom （qH^＋）, of which RE = 0.9606 and SD = 0.32. And the results of cross-validation test also show that the model exhibits optimum stability and better predictive power. Moreover, the predictive power of the new model is better than that of MCIs method.
基金This work was supported by the 973 National Basic Research Program of China (2003CB415002)the China Postdoctoral Science Foundation (No. 2003033486)
文摘Optimization calculations of 209 polychlorinated biphenyls （PCBs） were carried out at the B3LYP/6-31G^＊ level. It was found that there is significant correlation between the Cl substitution position and some structural parameters. Consequently, Cl substitution positions were taken as theoretical descriptors to establish a novel QSPR model for predicting –lgSw of all PCB congeners. The model achieved in this work contains four variables, of which r^2 = 0.9527, q^2 = 0.9490 and SD = 0.25 with large t values. In addition, the variation inflation factors （VIFs） of variables in this model are all less than 5.0, suggesting high accuracy of the –lgSw predicting model. And the results of cross-validation test and method validation also show that the model exhibits optimum stability and better predictive capability than that from the AM1 method.
基金Project supported by the 973 National Basic Research Program of China (2003CB415002)the Chinese Postdoctoral Science Foundation (No. 2003033486)
文摘Structural parameters of 36 fluorobenzene, chlorobenzene and bromobenzene compounds were computed at the B3LYP/6-31G^＊ level with DFT method. Based on the experimental data of aqueous solubility （–lgSw） and n-octanol/water partition coefficient （lgKow）, using the modified theoretical linear solvation energy relation （MTLSER） model, correlation equations that can predict –lgSw and lgKow were developed using structural parameters as theoretical descriptors. The correlation coefficients （r） of these equations are 0.9728 and 0.9967, respectively. These equations were further validated by variance inflation factors （VIF） and t-test methods and then used to predict –lgSw and lgKow values. By comparison, the correlation and predictive ability of our work are more advantageous than those calculated from valence molecular connectivity indices method and molecular topology index method.
基金This work was supported by the China Postdoctoral Science Foundation (No. 2003033486)
文摘Optimized calculation of dibenzofuran （DF） and 135 polychlorinated dibenzofurans （PCDFs） was carried out at the B3LYP/6-31G＊ level in GAUSSIAN 98 program. Based on the theoretical linear solvation energy relationship （TLSER） model, the obtained structural parameters were taken as theoretical descriptors to establish the novel quantitative structureproperty relationship （QSPR） model for predicting n-octanol/water partition coefficients （lgKow） of PCDFs. The new model of lgKow achieved in this work contains three variables： energy of the highest occupied molecular orbital （EHOMO）, the most negative atomic partial charge （q^-） and average molecular polarizability （a）, of which R^2= 0.9011 and SD = 0,17 with larger t values. In addition, the variation inflation factors （VIF） of variables in the present model are all less than 5.5, suggesting high accuracy of the lgKow model. And the results of cross-validation test （q^2 = 0.8688） and method validation also show this model exhibits optimum stability and better predictive power than semi-empirical method. At the same time, it is found that the aqueous solubility （-lgSw） has high relative correlation with constant volume molar heat capacity （Cv^0）, of which R^2 = 0.9777 and SD = 0.22. Moreover, lgKow and -lgSw values of all PCDF congeners were predicted respectively.
文摘在高效液相色谱(HPLC)测定方法的基础上,采用摇瓶法,准确测得25℃时16个取代苯硫酚类化合物的水溶解度(-lgSw)和19个正辛醇/水分配系数(lgKow)数据.采用密度泛函理论(DFT)中的B3LYP方法,在6-311G**基组上全优化计算得到24个取代苯硫酚的结构参数和热力学参数,采用SPSS12.0 for windows程序,分别求得-lgSw和lgKow值与这些参数之间的相关方程,相关系数R2分别为0.958和0.946.用交叉验证法对方程的稳定性进行了验证(q2分别为0.925和0.930),并用t检验和变异膨胀因子(Variance Inflation Factors,VIF)对两个方程中各变量的显著性和自相关性进行了检验.结果表明:所建方程具有较强的预测能力,并用其预测了8个没有实验数据的取代苯硫酚的-lgSw值和5个lgKow值.
