共查询到18条相似文献,搜索用时 156 毫秒
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为了预测环境污染物多溴代芴的热力学性质,计算了60种多溴代芴的分子连接性指数、电性距离矢量指数、电性拓扑状态指数以及分子形状指数.采用多元线性回归的方法建立了多溴代芴化合物的标准生成焓(Δ_fH~0)、标准熵(S~0)、标准生成吉布斯自由能(Δ_fG~0)及等容热容等热力学性质的QSPR相关性模型,方程的相关系数值均在0.99以上.与相关文献的相关系数R和标准误差S进行比较,该模型具有良好的预测能力和稳定性. 相似文献
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受Randic分子连接性拓扑指数^mZ的启发,本文构建了价电子轨道能量拓扑指数^mZ。用^mZ的0、1阶指数分别与无机氢化物的pKa1值、20种碱金属卤化物的晶格能U、生成焓△rHm、水化能△rG^0m和气态碱金属卤化物核间距R0关联,拟合的回归方程的相关系(指)数,满足优级或良级标准。预测取得较好的结果。 相似文献
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原子配分参数、配分连接性指数及其应用 总被引:9,自引:0,他引:9
结构决定性质,性质反映结构,这是化学、生物学等学科的一条基本规律。因此,分子的微观结构与性质之间存在着密切关系。物质的理化性质、生物活性等数据的获取,迄今主要来自于实验。如能建立结构与性能之间的数量关系用以估算与预测分子的性质,这无疑是一项十分有意义的工作。拓扑指数法以其计算简单、准确性高、应用范围广而在上述领域中发挥重要作用犤1~4犦。拓扑指数是对分子结构进行的定量描述,使分子之间的结构差异定量化。自Wiener提出第一个拓扑指数(W)犤5犦以来,迄今已有200余种拓扑指数问世。其中一部分能够有效地… 相似文献
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将直链烷烃分子看成是一个多自由度振动系统,用机械振动理论中的传递矩阵法计算了C2~C32直链烷烃的固有频率,分析了固有频率随化合物结构单元的变化规律.发现各阶固有频率中的基频与直链烷烃的结构型性质呈现出优良的相关性,用各阶固有频率之和表示的总频与直链烷烃的加和型性质也呈现出优艮的相关性,将两者组合后还能够反映直链烷烃的凝聚型性质的变化规律.在此基础上建立了直链烷烃的物化性能与基频和总频之间的定量相关模型.用该模型对直链烷烃的电离能、沸点、临界温度、临界压力、密度、粘度、标准生成焓、离子标准生成焓、常压热容、折光指数等10种不同类型性质的实验数据进行回归分析,相关系数均大于0.999. 相似文献
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用密度泛函理论B3LYP方法,在6-31G基组水平上,对12个全氟化合物分子进行了全优化计算,得到其分子零点振动能EZPV、热能校正值Eth、恒容热容CVΦ、标准熵SΦ以及配分函数lgQ等热力学参数,并计算了这些分子的电性拓扑状态指数Em.通过最佳变量子集回归建立了电性拓扑状态指数与热力学参数之间的QSPR模型,模型的相关系数R2分别为1.000,1.000,1.000,0.999和1.000,采用逐一剔除法得到的交叉验证相关系数R2cv分别为0.999,1.000,1.000,0.999和1.000,利用建构的数学模型得到热力学性质的相对平均误差分别为0.43%,0.41%,0.46%,0.41%和0.71%.从方程可以看出,F原子取代基数量是影响全氟化合物分子热力学参数大小的主要因素,检验证明所建模型具有良好的稳定性和预测能力. 相似文献
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在相对论有效原子实势近似下,用密度泛函B3LYP方法,求得PuC2气态分子的结构与不同温度下的热力学函数.根据热力学原理,计算得到PuC2气态分子在不同温度下的标准生成自由能变均为较大正值,据此说明, PuC2气态分子不具有热力学稳定性. 相似文献
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信息拓扑指数与烷烃分子热力学性质的关系 总被引:13,自引:0,他引:13
Two topological information indices were constructed based on Randic and Wiener indices, and the values of topological information indices for 85 alkanes were calculated. The thermodynamic properties such as the standard enthalpies of formation, the standard entropies and the standard free energies of formation for these alkanes were also correlated with these topological and information indices. It is found that the thermodynamic properties calculated for both gaseous and liquid states of the 85 alkanes are in excellent agreement with the experimental values through the regression analysis. 相似文献
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根据核磁共振的峰数及Randic的碳原子支化度,提出了碳原子特征值.基于连接矩阵和碳原子特征值,建立新的连接指数 mY.其中的0阶连接性指数 0Y很容易计算,且对烷烃异构体有很强的区分能力.将157种气态链烷烃的标准熵与其 0Y相关联, R=0.9985, 属于优级模型.与Randic指数的 0χ及倪才华等提出的信息拓扑指数Ix、 IW比较, 0Y具有良好的性质相关性与结构选择性. 相似文献
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电负性拓扑指数mF及其对无机物理化性质的预测 总被引:1,自引:0,他引:1
受Randic分子连接性拓扑指数 mX的启发,构建了电负性拓扑指数 mF.用 mF的0、 1阶指数分别与20种碱金属卤化物的晶格能U、生成焓ΔrHm、离子水化能ΔrGθm、 51种金属离子水合热ΔrHθh和80种离子标准生成热ΔfHθm进行关联,拟合的回归方程的相关系(指)数分别为0.9954(0.9954)、 0.9835(0.9840)、 0.9794(0.9795)、 0.9948和0.9865,满足优级或良级标准.结构选择性达到唯一性表征,预测取得满意的结果. 相似文献
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Bonchev D 《Journal of chemical information and computer sciences》2000,40(4):934-941
Earlier attempts to assess the complexity of molecules are analyzed and summarized in a number of definitions of general and topological complexity. A concept which specifies topological complexity as overall connectivity, and generalizes the idea of molecular connectivities of Randic, Kier, and Hall, is presented. Two overall connectivity indices, TC and TC1, are defined as the connectivity (the sum of the vertex degrees) of all connected subgraphs in the molecular graph. The contributions to TC and TC1, which originate from all subgraphs having the same number of edges e, form two sets of eth-order overall connectivities, eTC and eTC1. The total number of subgraphs K is also analyzed as a complexity measure, and the vector of its eth-order components, eK, is examined as well. The TC, TC1, and K indices match very well the increase in molecular complexity with the increase in the number of atoms and, at a constant number of atoms, with the increased degree of branching and cyclicity of the molecular skeleton, as well as with the multiplicity of bonds and the presence of heteroatoms. The potential of the three sets of eth-order complexities for applications to QSPR was tested by the modeling of 10 alkane properties (boiling point, critical temperature, critical pressure, critical volume, molar volume, molecular refraction, heat of formation, heat of vaporization, heat of atomization, and surface tension), in parallel with Kier and Hall's molecular connectivity indices (k)chi. The topological complexity indices were shown to outperform molecular connectivity indices in 44 out of the 50 pairs of models compared, including all models with four and five parameters. 相似文献
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烷基衍生物标准生成焓的QSPR研究 总被引:5,自引:0,他引:5
根据分子拓扑理论,建立了一个新的拓扑指数Y~X,并用Y~X对不同系列烷基衍生物M~nL(n=1,2,3;L=F,OH,Cl,NH~2,Br,SH,I;M=Me,Et;i-Pt,t-Bu,n-Pr,n-Bu,Amyl)的标准生成焓-△~fH~m^θ进行拟合,其相关系数均在0.999以上。计算结果表明,新的拓扑指数易于计算,物量意义明确,具有良好的结构选择性和性质相关性。该法可进一步用于估算其它烷基衍生物的标准生成焓。 相似文献
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An analysis of chemical thermodynamic properties of gaseous polynuclear aromatic compounds containing N-, S-, and O-heteroatoms and five-membered rings is presented. Standard enthalpies of formation, entropies and heat capacities taken from the literature, or derived from appropriate data, serve as the data base for this analysis. Enthalpies of formation are used to compute empirical resonance energies for polynuclear heteroaromatic structures which, in turn, allow critical examination of this property. An additive method is described for estimating entropies and heat capacities. New or revised values for thermodynamic properties for a number of polyaromatic substances are presented and recommended values for some common polyaromatics are given. 相似文献
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CaiHuaNI XianYuZENG HeHUANG 《中国化学快报》2005,16(5):709-710
Edge-adjacency index and information topological index for 82 molecules of alkanes nave been constructed and calculated. The topological indices were used to correlate with seven physical properties of the alkanes. Some empirical equations were obtained through regression. The regression and calculation results show a good agreement of the topological indices and the properties. 相似文献