The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and n -octanol/water partition coefficient of three groups of environmentally important chemicals-poly...The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and n -octanol/water partition coefficient of three groups of environmentally important chemicals-polychlorinated biphenyls(PCBs), polychlorinated dibenzodioxins and dibenzofurans(PCDDs and PCDFs). For each compound, five quantum parameters were calculated using AM1 semiempirical molecular orbital methods and used as structure descriptors: average molecular polarizability(α), energy of the lowest unoccupied molecular orbit( E _ LUMO ), energy of the highest occupied molecular orbit( E _ HOMO ), the most positive charge on a hydrogen atom( q _+), and the most negative atomic partial charge( q _-) in the solute molecule. Then standard independent variables in TLSER equation was extracted and two series of quantitative equations between these quantum parameters and aqueous solubility and n -octanol/water partition coefficient were obtained by stepwise multiple linear regression(MLR) method. The developed equations have both quite high accuracy and explicit meanings. And the cross-validation test illustrated the good predictive power and stability of the established models. The results showed that TLSER could be used as a promising approach in the estimation of partition and solubility properties of macromolecular chemicals, such as persistent organic pollutants.展开更多
用量子化学MOPAC-AM1法计算21种多环芳烃(PAHs)的SEDs(steric and electronic descriptors)参数,然后用多元线性回归法建立预测多环芳烃的沸点(BP)和辛醇/水分配系数(logK_(ow))等的QSPR模型,预测BP的模型含3个变量[前线轨道能量差(E_(l...用量子化学MOPAC-AM1法计算21种多环芳烃(PAHs)的SEDs(steric and electronic descriptors)参数,然后用多元线性回归法建立预测多环芳烃的沸点(BP)和辛醇/水分配系数(logK_(ow))等的QSPR模型,预测BP的模型含3个变量[前线轨道能量差(E_(lumo)-E_(homo))、分子总电子能(EE)和分子总连接性(TCon)],预测logK_(ow)的模型含3个变量[偶极矩(D)、分子总能量(TE)和分子总连接性(TCon)]。所建2个模型的相关系数的平方(R^2)分别为0.997 6和0.9861,交叉验证系数(R_(LOO)~2)分别为0.9820和0.9575,说明模型均具有很好的预测能力和较强的稳健性,同时也证明SEDs参数适用于多环芳烃类化合物的QSPR研究。展开更多
In this paper, according to the peak numbers of the nuclear magnetic resonance and the Randic embranchment degree (δ_i) of carbon atom i, the carbon atom’s environment valence g_i is defined as: g_i=(t_i+δ_i)/2.The...In this paper, according to the peak numbers of the nuclear magnetic resonance and the Randic embranchment degree (δ_i) of carbon atom i, the carbon atom’s environment valence g_i is defined as: g_i=(t_i+δ_i)/2.The g_i reflect the characteristic of each carbon atom, and as well as the conjunction detail of the carbon atom with other carbon atoms.So, the g_ i could distinguish better the chemical environment of each carbon atom in the molecule than δ_i.A connectivity index of environment valence ( mS) and its athwart index ( mS′) are proposed based on the adjacency matrix and the carbon atom’s environment valence g_i.Among them, the 0S and 0S′ include the characteristic and the connectivity of each carbon atom, the 1S and 1S′ reflect the second conjunction between carbon atoms.Based on 0S′ and N(the number of carbon atom), a new structural parameter——symmetry degree (N_ ec), is defined as: N_ ec=[(0S′_S/0S′_C)N] 2/3,and the N_ ec reflect the size of the molecule as well as the symmetry of the molecule.The N_ ec, 0S and R_n(the biggest ring’s edge numbers of cycloalkanes) of 474 saturated hydrocarbons (216 paraffins and 258 cycloalkanes) were calculated and correlated with their boiling points.The best regression equation was obtained as follow: ln(1056-T_b)=6.9480-0.1040N_ ec -0.0086890S-0.009614R_ n+0.01998R 0.5_n,n=474,R=0.9989,F=52627,S=5.63K.The model was checked up by the Jackknife’s method.It should have overall steadiness and could be used for predicting the boiling point of saturated hydrocarbons.展开更多
Based on the partition function in statistical thermodynamics, atomic partit ion parameter fi =lg[(ni－1)0.5·Ar,i] is introduced in this paper. The fi has demonstrated good unitarity for all the ground state ato ...Based on the partition function in statistical thermodynamics, atomic partit ion parameter fi =lg[(ni－1)0.5·Ar,i] is introduced in this paper. The fi has demonstrated good unitarity for all the ground state ato ms, and excellent correlativity with the standard entropies (,J·mol－1·K －1) of 70 cations in solid compounds: = －10.247＋27.508 fi , r=0.996. A satisfactory curve equation is developed as follows: =6.229＋13.257 fi1.5, r= 0.999. On the basis of adjacency matrices and fi , a novel partition connectivit y index is developed for the study on the standard entropies of 64 S block compo unds. The linear regression equation is set up by the least square method: =－3 9.416＋33.9610H, r=0.985. The binary linear equation among and 0H, nM (princip al quantum number of the ground state atoms for S block) is drawn up: =－21.591 ＋32.0720H－31.013nM－1, R=0.990. The calculated values of basically tally w ith the experiment values. fi and 0H demonstrate that the method possesses the a dvantage of easy computation and clear physical significance.展开更多
Twenty eight alkyl(1-phenylsulfonyl) cycloalkane carboxylates were computed at the B3LYP/6-31G* level. Based on linear solvation energy theory, two quantitative correlation equations of the molecular structures of alk...Twenty eight alkyl(1-phenylsulfonyl) cycloalkane carboxylates were computed at the B3LYP/6-31G* level. Based on linear solvation energy theory, two quantitative correlation equations of the molecular structures of alkyl(1-phenylsulfonyl) cycloalkane carboxylate com- pounds to their chromatographic retention (capacity factor lgKW) and the toxicity for photo- bacterium phosphoreum (–lgEC50) were developed by using the molecular structural parameters as theoretical descriptors (r2 = 0.9501, 0.9488). The two quantitative correlation equations were consequently cross validated by leave-one-out (LOO) validation method with q2 of 0.9113 and 0.9281, respectively. The result showed that the two equations achieved in this work by B3LYP/6-31G* are both more advantageous than those from AM1, and can be used to predict the lgKW and –lgEC50 of congeneric organics.展开更多
基金TheNationalKeyBasicResearchFoundationofChina (No .G1 9990 4 571 1 )
文摘The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and n -octanol/water partition coefficient of three groups of environmentally important chemicals-polychlorinated biphenyls(PCBs), polychlorinated dibenzodioxins and dibenzofurans(PCDDs and PCDFs). For each compound, five quantum parameters were calculated using AM1 semiempirical molecular orbital methods and used as structure descriptors: average molecular polarizability(α), energy of the lowest unoccupied molecular orbit( E _ LUMO ), energy of the highest occupied molecular orbit( E _ HOMO ), the most positive charge on a hydrogen atom( q _+), and the most negative atomic partial charge( q _-) in the solute molecule. Then standard independent variables in TLSER equation was extracted and two series of quantitative equations between these quantum parameters and aqueous solubility and n -octanol/water partition coefficient were obtained by stepwise multiple linear regression(MLR) method. The developed equations have both quite high accuracy and explicit meanings. And the cross-validation test illustrated the good predictive power and stability of the established models. The results showed that TLSER could be used as a promising approach in the estimation of partition and solubility properties of macromolecular chemicals, such as persistent organic pollutants.
文摘用量子化学MOPAC-AM1法计算21种多环芳烃(PAHs)的SEDs(steric and electronic descriptors)参数,然后用多元线性回归法建立预测多环芳烃的沸点(BP)和辛醇/水分配系数(logK_(ow))等的QSPR模型,预测BP的模型含3个变量[前线轨道能量差(E_(lumo)-E_(homo))、分子总电子能(EE)和分子总连接性(TCon)],预测logK_(ow)的模型含3个变量[偶极矩(D)、分子总能量(TE)和分子总连接性(TCon)]。所建2个模型的相关系数的平方(R^2)分别为0.997 6和0.9861,交叉验证系数(R_(LOO)~2)分别为0.9820和0.9575,说明模型均具有很好的预测能力和较强的稳健性,同时也证明SEDs参数适用于多环芳烃类化合物的QSPR研究。
文摘In this paper, according to the peak numbers of the nuclear magnetic resonance and the Randic embranchment degree (δ_i) of carbon atom i, the carbon atom’s environment valence g_i is defined as: g_i=(t_i+δ_i)/2.The g_i reflect the characteristic of each carbon atom, and as well as the conjunction detail of the carbon atom with other carbon atoms.So, the g_ i could distinguish better the chemical environment of each carbon atom in the molecule than δ_i.A connectivity index of environment valence ( mS) and its athwart index ( mS′) are proposed based on the adjacency matrix and the carbon atom’s environment valence g_i.Among them, the 0S and 0S′ include the characteristic and the connectivity of each carbon atom, the 1S and 1S′ reflect the second conjunction between carbon atoms.Based on 0S′ and N(the number of carbon atom), a new structural parameter——symmetry degree (N_ ec), is defined as: N_ ec=[(0S′_S/0S′_C)N] 2/3,and the N_ ec reflect the size of the molecule as well as the symmetry of the molecule.The N_ ec, 0S and R_n(the biggest ring’s edge numbers of cycloalkanes) of 474 saturated hydrocarbons (216 paraffins and 258 cycloalkanes) were calculated and correlated with their boiling points.The best regression equation was obtained as follow: ln(1056-T_b)=6.9480-0.1040N_ ec -0.0086890S-0.009614R_ n+0.01998R 0.5_n,n=474,R=0.9989,F=52627,S=5.63K.The model was checked up by the Jackknife’s method.It should have overall steadiness and could be used for predicting the boiling point of saturated hydrocarbons.
文摘Based on the partition function in statistical thermodynamics, atomic partit ion parameter fi =lg[(ni－1)0.5·Ar,i] is introduced in this paper. The fi has demonstrated good unitarity for all the ground state ato ms, and excellent correlativity with the standard entropies (,J·mol－1·K －1) of 70 cations in solid compounds: = －10.247＋27.508 fi , r=0.996. A satisfactory curve equation is developed as follows: =6.229＋13.257 fi1.5, r= 0.999. On the basis of adjacency matrices and fi , a novel partition connectivit y index is developed for the study on the standard entropies of 64 S block compo unds. The linear regression equation is set up by the least square method: =－3 9.416＋33.9610H, r=0.985. The binary linear equation among and 0H, nM (princip al quantum number of the ground state atoms for S block) is drawn up: =－21.591 ＋32.0720H－31.013nM－1, R=0.990. The calculated values of basically tally w ith the experiment values. fi and 0H demonstrate that the method possesses the a dvantage of easy computation and clear physical significance.
基金This work was financially supported by the National Basic Research Program of China (2003CB415002), the China Postdoctoral Science Foundation (No. 2003033486) and the Natural Science Research Fund of University in Jiangsu (04KJB150149)
文摘Twenty eight alkyl(1-phenylsulfonyl) cycloalkane carboxylates were computed at the B3LYP/6-31G* level. Based on linear solvation energy theory, two quantitative correlation equations of the molecular structures of alkyl(1-phenylsulfonyl) cycloalkane carboxylate com- pounds to their chromatographic retention (capacity factor lgKW) and the toxicity for photo- bacterium phosphoreum (–lgEC50) were developed by using the molecular structural parameters as theoretical descriptors (r2 = 0.9501, 0.9488). The two quantitative correlation equations were consequently cross validated by leave-one-out (LOO) validation method with q2 of 0.9113 and 0.9281, respectively. The result showed that the two equations achieved in this work by B3LYP/6-31G* are both more advantageous than those from AM1, and can be used to predict the lgKW and –lgEC50 of congeneric organics.
