计算机结构自动解析专家系统--空间异构体穷举生成算法

提出了一种穷举生成化合物立体异构体的算法. 该方法包括以下3个步骤: 首先输入该化合物的二维连接表, 查找该化合物中不对称碳和碳碳双键所产生的立体中心. 然后, 在自同构划分的基础上得到以该二维连接表作为图的自同构群. 最后, 通过立体中心在自同构群的作用下得到不同的等价类, 即可穷举生成该拓扑结构的所有可能的立体异构体. 最终得到的立体异构体用2.5维连接表表示.     

计算机自动结构解析专家系统研究──一个新的拓扑等价性识别算法

介绍了一个正确识别化合物结构或结构片断中各原子的拓扑等价性问题的新算法。算法中引入了节点矩阵Ｎ和键矩阵Ｂ，并由这两个新矩阵来计算化合物结构图中的各节点的特征值，以此来表征节点的环境特征，从而识别节点的拓扑等价性，以保证结构解析专家系统结构产生器的穷举和非冗余性。     

计算机自动结构解析专家系统研究—一个新的拓扑等价性识别…

介绍了一个正确识别化合物结构片断中各原子的拓扑等价性问题的新算法，算法中引入了节点矩阵Ｎ和键矩阵Ｂ，并由这两个新矩阵来计算化合物结构图中的各节点的特征值，以此来表征节点的环境特征，从而识别节点的拓扑等价性，以保证结构解析专家系统结构产生器的穷举和非冗余性。     

计算机辅助有机化合物结构解析ESESOC—Ⅱ

简要介绍了有机化合物结构自动解析专家系统ＥＳＥＳＯＣ－Ⅱ及其结构产生器由分子式穷举生成有机化合物结构异构体的基本算法。主要讨论了结构２产生器的穷举性，非冗性和有效性问题。     

计算机辅助有机化合物结构解析ESESOC-Ⅱ

简要介绍了有机化合物结构自动解析专家系统ＥＳＥＳＯＣ－Ⅱ及其结构产生器由分子式穷举生成有机化合物结构异构体的基本算法。主要讨论了结构产生器的穷举性、非冗性和有效性问题。     

CoTPP电化学催化原溴代环己烷的机理

以电化学循环伏安、现场ＥＳＲ电化学以及现场薄层电化学方法研究了电生Ｃｏ（Ｉ）ＴＰＰ与溴代五己烷的反机制。在ＤＭＦ中，Ｃｏ（Ⅱ）／Ｃｏ（Ⅰ）的氧化还原有明显的催化溴代环己烷还原的特片，反现场有自由基生成，反应产物之一是Ｃｏ－Ｃ键化合物，可以在１．３０Ｖ（ＳＣＥ）－电子还原，当存在ＣＨ２－ＣＨＣＮ时，。生成另一种Ｃｏ－Ｃ键化合物，该化合物在－１．１０Ｖ（ＳＣＥ）处一电子还原，证明溴代环己烷与Ｃｏ（Ｉ）     

RE2CuO4的热力学稳定性（RE=La,Nd,Sm,Eu）

构筑了ＭｇＯ部分稳定的ＺｒＯ２基固体电解质电化学电池测量ＥＡＦ的实验装置，测定了Ｓｍ２ＣｕＯ４的标准Ｇｉｂｂｓ生成自由能。结果表明化合物ＲＥ２ＣｕＯ２３（ＲＥ＝Ｌａ，Ｎｄ，Ｓｍ，Ｅｕ）随着镧系元素离子半径减小，热力学稳定性下降，并用晶体场理论解释了这一规律。     

最佳定域分子轨道的新算法

本文提出了最佳群对称定域分子轨道（ＯＳＬＭＯＳ）的概念，报道了ＯＳＬＭＯｓ的生成方法。ＯＳＬＭＯｓ满足分子对称、等价与正交；同时最佳逅近经典的非正交价键型轨道，并可作为ＭＣＳＣＦ与ＣＩ方法中的单电子轨道。     

化学键的高选择性拓扑指数及应用

基于分子和原子的高选择性拓扑指数, 提出了化学键的高选择性拓扑指数bATID. 分别采用300余万个化学键的虚拟数据集和实际数据集检验bATID的唯一性, 未发现简并, 即bATID具有较强的化学键区分能力. 进一步将bATID应用于有机化合物的化学键识别, 获得了较好结果. 如, 利用bATID可识别出富勒烯C₆₀的90个化学键为30个6∶6键和60个5∶6键. 研究还表明, bATID的化学键识别可应用于手性中心自动设定和自同构群穷举生成的顶点置换.     

有机化合物结构的唯一性表征方法研究——一个高选择性的拓扑…

以扩展连接矩阵ＥＡ的幂级数函数为基础，建立了一个新的拓扑指数ＥＡＴＩ，该指数对１￣２２个碳原子的所有３８０７４３４个烷烃异构体的指认并不出现简并，且能区分含杂原子的化合物，其唯一性良好。该指数可用于数据库中替代ＣＡＳ登录号进行结构的编码、管理及检索。     

Molecular symmetry perception

An algorithm for molecular symmetry perception is presented. The method identifies the full set of molecular symmetry elements (proper and improper) and determines their coordinates. The algorithm eliminates the necessity to explore the entire graph automorphism group; as a result its computer application is extremely effective. Application to several dendrimers and fullerenes with high topological symmetry is presented.     

Understanding topological symmetry: a heuristic approach to its determination

An algorithm based on heuristic rules for topological symmetry perception of organic structures having heteroatoms, multiple bonds, and any kind of cycle, and configuration, is presented. This algorithm identifies topological symmetry planes and sets of equivalent atoms in the structure, named symmetry atom groups (SAGs). This approach avoids both the need to explore the entire graph automorphism groups, and to encompass cycle determination, resulting in a very effective computer processing. Applications to several structures, some of them highly symmetrical such as dendrimers, are presented.     

Symmetry calculation for molecules and transition states

The symmetry of molecules and transition states of elementary reactions is an essential property with important implications for computational chemistry. The automated identification of symmetry by computers is a very useful tool for many applications, but often relies on the availability of three‐dimensional coordinates of the atoms in the molecule and hence becomes less useful when these coordinates are a priori unavailable. This article presents a new algorithm that identifies symmetry of molecules and transition states based on an augmented graph representation of the corresponding structures, in which both topology and the presence of stereocenters are accounted for. The automorphism group order of the graph associated with the molecule or transition state is used as a starting point. A novel concept of label‐stereoisomers, that is, stereoisomers that arise after labeling homomorph substituents in the original molecule so that they become distinguishable, is introduced and used to obtain the symmetry number. The algorithm is characterized by its generic nature and avoids the use of heuristic rules that would limit the applicability. The calculated symmetry numbers are in agreement with expected values for a large and diverse set of structures, ranging from asymmetric, small molecules such as fluorochlorobromomethane to highly symmetric structures found in drug discovery assays. The new algorithm opens up new possibilities for the fast screening of the degree of symmetry of large sets of molecules. © 2014 Wiley Periodicals, Inc.     

A graph theory-based “expert system” methodology for structure-activity studies

A new graph theory-based methodology is proposed for the statistical evaluation of the link between the structure and the chemical/biological activity of organic molecules. The computer-aided analysis involves the heuristic processing of molecules as chemical graphs which are decomposed into their component subgraphs. Common topological features among the subgraphs are then statistically isolated, and a set of rules is developed that can be used to explain the activities of the analyzed compounds as well as predict the activities of new compounds. The validity of the methodology is demonstrated by its application to actual experimental data.     

三梯级和四梯级圆筒和Mbius分子的拓扑特性研究

Walba等以其卓越的工作,合成了三-THYME(C_(42)H_(72)O_(18))和四-THYME(C_(56)H_(96)O_(24))圆筒及其Mbius扭曲环带分子,被誉为拓扑学进入有机化学领域的奇迹,成为迄今为止拓扑立体化学研究的重要内容,但从拓扑学的观点探索分子图拓扑结构特性尚缺乏深入研究,本文作者考虑到一般性,曾将扭曲数T为偶数(0,2,4)的定义为Hckel型,扭曲数     

A simple algorithm for unique representation of chemical structures-cyclic/acyclic functionalized achiral molecules

An algorithm, based on "vertex priority values" has been proposed to uniquely sequence and represent connectivity matrices of chemical structures of cyclic/acyclic functionalized achiral hydrocarbons and their derivatives. In this method, "vertex priority values" have been assigned in terms of atomic weights, subgraph lengths, loops, and heteroatom contents. Subsequently, the terminal vertices have been considered upon completing the sequencing of the core vertices. This approach provides a multilayered connectivity graph, which can be put to use in comparing two or more structures or parts thereof for any given purpose. Furthermore, the basic vertex connection tables generated here are useful in the computation of characteristic matrices/topological indices and automorphism groups and in storing, sorting, and retrieving chemical structures from databases.     

The heptakisoctahedral group and its relevance to carbon allotropes with negative curvature

We introduce the pollakispolyhedral groups and describe in detail the representational structure of PSL(2,7) or ⁷ O, the automorphism group of the Klein graph composed of 56 trivalent vertices arranged in 24 heptagonal faces. Leapfrog and quadruple transformations of the graph are described and their eigenvalue spectra derived. Considered as carbon frameworks on the “plumber's nightmare” surface these chiral structures exhibit significant steric strain which prevents the molecular realisation of the Klein symmetry. This revised version was published online in July 2006 with corrections to the Cover Date.     

Symmetry properties of chemical graphs VIII. On complementarity of isomerization modes

Isomerization mode defines the process of interconversion of one isomer into another. Several mechanisms are conceivable for degenerate rearrangements and, in general, lead to a distinctive network of relations between participating isomers. Here we consider selected modes which are complementary in the sense that if mode 1 transforms an isomer A into B, C, D etc., then mode 2 transforms the same isomer A into X, Y, Z, etc., which includes all isomers not comprised by the first mode. Physico-chemical complementarity can be translated into mathematical complementarity of associated chemical graphs. This allows us to use the tool of Graph Theory. One example of graph theoretical use is the theorem that graph G and its complement G have the same automorphism group (i.e., the same symmetry). We have shown that a close examination of a graph and its complement and their components allows us to recognize the automorphism group in some complex cases without resorting to canonical numbering or other involved procedures, and even allows us to determine isomorphism of different processes.Dedicated to Professor Kurt Mislow of Princeton UniversityOperated for the U.S. Department of Energy by Iowa State University under contract W-7405-Eng-82. Supported in part by the Office of the Director.     

Unique description of chemical structures based on hierarchically ordered extended connectivities (HOC procedures). III. Topological,chemical, and stereochemical coding of molecular structure

A topological code is devised on the basis of the unique topological representation of the molecule described in the preceding two parts of this series.¹ By adding to the topological code additional chemical information on atoms and/or bonds, as well as stereochemical information, a chemical and respectively stereochemical code (SHOC) are also constructed. The advantages of the new linear codes are that they are convention-free codes, preserving the symmetry of molecular graph, and easily implemented either manually or by means of computer programs. By concentrating all topological, chemical, and stereochemical information, our code (SHOC) is more compact and more general than the codes based on several separate lists.