以物质的电子、空间等结构性质为基础,运用Gaussian98和Cerius2程序包对偶极距(Dipole)、最高占据轨道能量(EHOMO)、最低空轨道能量(ELUMO)、分子总能量(E)、旋转键(Rotlbonds)、最弱的R-NO2键长(R-NO2 bond length,R为C或N)、氢键供体(...以物质的电子、空间等结构性质为基础,运用Gaussian98和Cerius2程序包对偶极距(Dipole)、最高占据轨道能量(EHOMO)、最低空轨道能量(ELUMO)、分子总能量(E)、旋转键(Rotlbonds)、最弱的R-NO2键长(R-NO2 bond length,R为C或N)、氢键供体(Hbond donor)和中点势(Vmid)8种描述符进行了计算,采用Cerius2程序包中的QSPR方法建立了芳香系炸药密度与8种描述符之间的构效关系式,相关系数R为0.909,30个化合物所构成的训练集和15个化合物所构成的预测集预测密度与实测密度之间的平均误差分别为3.33%和2.94%。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
基于密度泛函理论,利用多氯二苯并对二噁英(PCDDs)和多氯二苯并呋喃(PCDFs)几何构型全优化而得的量子化学和延伸计算参数:前线轨道能、熵、无迹四极矩、分子绝对硬度、电负性和亲电指数等,对两类化合物在(虹鳉)脂-水间的平衡分配性质进...基于密度泛函理论,利用多氯二苯并对二噁英(PCDDs)和多氯二苯并呋喃(PCDFs)几何构型全优化而得的量子化学和延伸计算参数:前线轨道能、熵、无迹四极矩、分子绝对硬度、电负性和亲电指数等,对两类化合物在(虹鳉)脂-水间的平衡分配性质进行了定量化模型研究,并由多元线性回归分析(MLR)建立了二次函数型的定量结构-性质相关关系(QSPR):lgKbw=5.343-0.001(S-125.480)2-0.355(ω-3.239)2+0.006(Qzz-2.950)2-22.728(η-2.365)2.结果表明,模型具有较高的拟合优度与稳健性,其决定系数和交叉验证相关系数分别为0.943和0.908,且模型的内外部预测性能理想,总体质量明显优于SOFA(solubility parameter for fate analysis)计算结果,可用于未知脂-水分配性质的预测;PCDD/Fs脂-水平衡分配(系数)主要与分子体积以及由电荷分布决定的芳烃分子间相互作用有关,也受潜在的生物转化和分子反应性的影响.展开更多
文摘以物质的电子、空间等结构性质为基础,运用Gaussian98和Cerius2程序包对偶极距(Dipole)、最高占据轨道能量(EHOMO)、最低空轨道能量(ELUMO)、分子总能量(E)、旋转键(Rotlbonds)、最弱的R-NO2键长(R-NO2 bond length,R为C或N)、氢键供体(Hbond donor)和中点势(Vmid)8种描述符进行了计算,采用Cerius2程序包中的QSPR方法建立了芳香系炸药密度与8种描述符之间的构效关系式,相关系数R为0.909,30个化合物所构成的训练集和15个化合物所构成的预测集预测密度与实测密度之间的平均误差分别为3.33%和2.94%。
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.
文摘基于密度泛函理论,利用多氯二苯并对二噁英(PCDDs)和多氯二苯并呋喃(PCDFs)几何构型全优化而得的量子化学和延伸计算参数:前线轨道能、熵、无迹四极矩、分子绝对硬度、电负性和亲电指数等,对两类化合物在(虹鳉)脂-水间的平衡分配性质进行了定量化模型研究,并由多元线性回归分析(MLR)建立了二次函数型的定量结构-性质相关关系(QSPR):lgKbw=5.343-0.001(S-125.480)2-0.355(ω-3.239)2+0.006(Qzz-2.950)2-22.728(η-2.365)2.结果表明,模型具有较高的拟合优度与稳健性,其决定系数和交叉验证相关系数分别为0.943和0.908,且模型的内外部预测性能理想,总体质量明显优于SOFA(solubility parameter for fate analysis)计算结果,可用于未知脂-水分配性质的预测;PCDD/Fs脂-水平衡分配(系数)主要与分子体积以及由电荷分布决定的芳烃分子间相互作用有关,也受潜在的生物转化和分子反应性的影响.
