Structure and properties of organic molecules. 1. Three-dimensional topological indices of alkanes

The Winer and Schultz three-dimensional topological indices of alkanes are considered and compared with ordinary two-dimensional indices. Methods of index design and details of calculations are discussed. Unlike two-dimensional indices, three-dimensional ones adequately reflect differences between both structural and rotational isomers. Regression analysis of property-index correlations for formation enthalpy, molar volume, evaporation heat, and boiling temperature is performed using various two- and three-parameter (linear, quadratic, exponential, logarithmic, and power) functions. The ability of three-dimensional indices to correlate with these properties is found to be as good as that of two-dimensional ones. Tver State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 3, pp. 484–492, May–June, 1998. This work was supported by RFFR grant No. 96-03-32384.     

Correlations of indices calculated from the matrix of maximal topological distances with boiling points of alkylbenzenes

The matrix of maximal topological distances of a graph can serve as a basis for constructing new topological indices of ringcontaining structures. A comparative study of the structureproperty correlations of the indices of the matrix of maximal topological distances and known Wiener, Horary, and Schultz indices (instructive sample of 29 alkylbenzenes) showed that the best two- and three-parameter correlations with boiling points include the indices of the maximal distance matrix. The two-parameter (r = 0.0992, s = 3.5) and three-parameter (r = 0.994, s = 3.1) correlations may be used for quantitative predictions of the boiling points of alkylbenzenes. Translated fromZhumal Struktumoi Khimii, Vol. 38, No. 1, pp. 167–172, January–February, 1997.     

Molecular modeling of wine polyphenols

Due to wide range of health effects of wine polyphenols, it is important to investigate the relationship between their structure and physical properties (quantitative structure–property relationship, QSPR). We have investigated linear, nonlinear (polynomial), and multiple linear relationships between given topological indices and molecular properties of main pharmacological active components of wine, such as molecular weight (MW), van der Waals volume (Vw), molar refractivity (MR), polar molecular surface area (PSA) and lipophilicity (log P). Partition coefficient (log P) was calculated using three different computer program (CLOGP, ALOGPS and MLOGP). The best models were achieved using the MLOGP program. Topological indices used for correlation analysis include: the Wiener index, W(G); connectivity indices, χ(G); the Balaban index, J(G); information-theoretic index, I(G); and the Schultz index, MTI(G). QSPR was performed on the set of 19 polyphenols and, particularly, on the group of phenolic acids, and on the group of flavonoids with resveratrol. The connectivity index has been successfully used for describing almost all parameters. Significant correlations were achieved between the Wiener index and van der Waals volume, as well as molecular weight.     

Generalized Hosoya polynomials of hexagonal chains

Similar to the well-known Wiener index, Eu et al. [Int. J. Quantum Chem. 106 (2006) 423–435] introduced three families of topological indices including Schultz index and modified Schultz index, called generalized Wiener indices, and gave the similar formulae of generalized Wiener indices of hexagonal chains. They also mentioned three families of graph polynomials in x, called generalized Hosoya polynomials in contrast to the (standard) Hosoya polynomial, such that their first derivatives at x = 1 are equal to generalized Wiener indices. In this note we gave explicit analytical expressions for generalized Hosoya polynomials of hexagonal chains.     

Extended molecular connectivity: Prediction of boiling points of alkanes

It is shown that extended molecular connectivity may be used for “structure-property” studies. The statistical parameters of the correlation relations of boiling points with extended molecular connectivity indices found for a sample of alkanes (n = 74) are the following: the best two-parameter correlation r = 0.9948, s = 4.7; the best three-parameter correlation r = 0.9971, s = 3.5. Translated fromZhurnal Strukturnoi Khimii, Vol. 38, No. 6, pp. 1154–1159, November–December, 1997.     

Topological approach in determining the structure-property dependence in a series of 4-cyclohexene-1,2-dicarboxylic acids

Theoretical information indices of cis- and trans-4-cyclohexene-1,2-dicarboxylic acids and their methyl and dimethyl substituted derivatives are calculated. Correlations between the indices and physicochemical properties of these compounds are analyzed. Original Russian Text Copyright ? 2009 by M. S. Salakhov, B. T. Bagmanov, and O. T. Grechkina __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 1, pp. 183–187, January–February, 2009.     

Graph and hypergraph models of molecular structure: A comparative analysis of indices

Eight series of molecular structures represented by molecular hypergraphs and molecular graphs are considered. A comparative analysis is performed for 23 integral topological and information theoretical indices for the graph and hypergraph models. For each series, the sensitivity is studied on both models, correlations are established for indices inside the models, and indices not correlating with each other are found. The results of this analysis showed that the sensitivity of most indices is higher in the hypergraph model. The total number of noncorrelated indices also increases in the latter model. Translated fromZhurnal Struktumoi Khimii, Vol. 39, No. 6, pp. 1163–1171, November–December, 1998.     

Use of molecular connectivity indices to predict LC retention of dansylamides in six different eluent systems

Summary Molecular connectivity indices (x) through the sixth order were calculated and compared with measured reversed-phase liquid chromatographic retention data of sixteen dansyl derivatives of amines (dansylamides). Retention measurements were performed in the capacity factor, k′, range 1–30 with organic solvent-water eluents using acetone, acetonitrile, ethanol, methanol, 1-propanol and 2-propanol. Mainly valence level indices were selected to describe retention. Indices of different order were selected in the different eluents, suggesting that there are differences in the retention mechanism in these eluents. Retention can be predicted with great accuracy by the molecular connectivity indices, as the high correlations between the calculated and observed retention indicate. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

Generalized Wiener indices of zigzagging pentachains

The “pentachains” studied in this paper are graphs formed of concatenated 5-cycles. Explicit formulas are obtained for the Schultz and modified Schultz indices of these graphs, as well as for generalizations of these indices. In the process we give a more refined version of the procedure that earlier was reported for the ordinary Wiener index.     

A method of finding an informative set of molecular graph indices for the prediction of chemical compound properties

The method and algorithms for predicting properties of chemical compounds by their quantitative structural characteristics, in particular, molecular graph indices, are presented. The prediction procedure consists of establishing the priority of indices for training sample compounds, classifying control sample compounds in the Euclidean space of indices, and finding a locally optimum (informative) index set giving a least prediction error. The algorithms have been successfully tested using the BACC system (analysis and classification of biologically active compounds), created at the S. V. Sobolev Institute of Mathematics of the Siberian Branch of the Russian Academy of Sciences. Translated fromZhumal Strukturnoi Khimii, Vol. 38, No. 4, pp. 795–802, July–August, 1997.     

Identification by GC—MS of cymene isomers and 3,7,7-trimethylcyclohepta-1,3,5-triene in essential oils

Retention indices of cymene isomers published in popular GC—MS atlases were found to be erroneous by analyzing synthetic samples. The following retention indices (RI) were found using a nonpolar phase (diphenyl: dimethylpolysiloxane, 5:95) for four essential-oil components with indistinguishable mass spectra: 3,7,7-trimethylcyclohepta-1,3,5-triene (RI = 970), m-cymene (RI = 1022), p-cymene (RI = 1024), and o-cymene (RI = 1039). The relative distributions of these compounds were evaluated based on the analysis of about 1000 essential oils. Simple methods were given for preparing standard mixtures of isomeric compounds for identification by GC—MS. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 569–571, November–December, 2006.     

Prediction of plasma protein binding of drugs using Kier–Hall valence connectivity indices and 4D-fingerprint molecular similarity analyses

Summary A 115 compound dataset for HSA binding is divided into the training set and the test set based on molecular similarity and cluster analyses. Both Kier–Hall valence connectivity indices and 4D-fingerprint similarity measures were applied to this dataset. Four different predictive schemes (SM, SA, SR, SC) were applied to the test set based on the similarity measures of each compound to the compounds in the training set. The first algorithmic scheme (SM) predicts the binding affinity of a test compound using only the most similar training set compound’s binding affinity. This scheme has relatively poor predictivity based both on Kier–Hall valence connectivity indices similarity measures and 4D-fingerprints similarity analyses. The other three algorithmic schemes (SM SR, SC), which assign a weighting coefficient to each of the top-ten most similar training set compounds, have reasonable predictivity of a test set. The algorithmic scheme which categorizes the most similar compounds into different weighted clusters predicts the test set best. The 4D-fingerprints provide 36 different individual IPE/IPE type molecular similarity measures. This study supports that some types of similarity measures are highly similar to one another for this dataset. Both the Kier–Hall valence connectivity indices similarity measures and the 4D-fingerprints have nearly same predictivity for this particular dataset.     

Forming taxonomic groups of organic compounds for calculating gas-chromatographic retention indices from physicochemical constants

The traditional approach to calculations of gas-chromatographic retention indices from physicochemical constants of organic compounds in homologous series does not encompass all possible objects. Forming different taxonomic groups of compounds by variations in the formal unsaturation, the number of atoms of different elements within molecules, or any complex fragments of structure/composition makes it possible to calculate unknown retention indices by several independent methods from different arrays of initial data. The application of simple three-parameter equations provides an accuracy comparable to the modern interlaboratory error of determination of retention indices for any compounds. St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 6, pp. 176–182, November–December, 1994. Translated by L. Smolina     

Topological analysis of the structure-mesomorphous property ralationship

The use of topological indices to reveal the relationship between molecular structure and mesomorphous properties is discussed. Mathematical models for classification of mesophase types are proposed. The effect of molecular structure and attractive ability on phase transition temperatures is described. Examples of using correlation equations to predict the properties of 2,5-disubstituted 1,3-dioxanes are given. A. V. Bogatskii Physicochemical Institute, Ukrainian Academy of Sciences. Translated fromZhurnal Struktumoi Khimii, Vol. 35, No. 4, pp. 53–60, July–August, 1994. Translated by L. Smolina     

Gas-liquid chromatography of thioesters of perfluorocarboxylic acids 1. Characteristics of retention

Retention of thioesters of perfluoropentanoic acid C₄F₉C(O)SR was studied by GLC on packed and capillary columns using stationary phases SE-30, SKTFT-50X, XE-60, and Carbowax 20M. The retention indices of these compounds were calculated, and their relationship with the structure of the compounds and the conditions of the analysis were established. Translated fromIzvestiya Akademii, Nauk. Seriya Khimicheskaya, No. 5, pp. 984–986, May, 1997.     

Generalized characteristics of mass spectra of aromatic compounds and their correlation with the constants of substituants

A scheme for calculating generalized mass-spectral characteristics (indices) is suggested. The indices were formed by using a set of parameters determined experimentally: mass numbers (m/z) and intensities of ion peaks (I). Linear correlations of mass-spectral indices with Hammett constants are established for several classes of aromatic and heteroaromatic compounds (azo compounds, azomethines, amides, triazenes).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2073–2077, December, 1993.This work was supported by the Russian Foundation for Basic Research (Grant 93-03-4424).     

Molecular structure and electronic effects of chlorophosphorane from mndo calculations and35Cl NQR data

The molecular geometries of eleven compounds of pentacoordinated phosphorus are optimized and charges on the central phosphorus atom and on the ligands are calculated by the semiempirical MNDO method. In cases of chlorine atoms as ligands, correlations between the chlorine-35 NQR frequencies and charges on the chlorine atoms of P-Cl bonds, on the one hand, and these bond lengths, on the other, are established. Parameters of the corresponding correlation equations are obtained and discussed. The efficiency of this calculation procedure and NQR method for analyzing the geometrical structure and electron distributions in chlorophosphorane molecules is shown. Translated fromZhurnal Struktumoi Khimii, Vol. 38, No. 6, pp. 1074–1082, November–December, 1997.     

Structural analogy principle for estimating gas chromatographic retention indices

It is shown that using additive schemes complying with the general principle of structural analogy for all molecular transformations is admissible for calculating gas chromatographic retention indices, which are very important analytical parameters for identification of organic compounds. From this viewpoint, we compare the possibilities of using the homomorphism factors and the fit increments of the retention indices of reagents and products in chemical reactions, including those of some topochemically equivalent hypothetical transformations of the structure and composition of organic molecules. Scientific-Research Institute of Chemistry, St. Petersburg University. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 4, pp. 784–795, July–August, 1996. Translated by L. Smolina     

A novel ferrocenylalkylating reagent. Ferrocenylalkylation of imidazole and its derivatives

Reactions of α-(1-benzotriazolyl)ethylferrocene (1) with 1,2,4-triazole, imidazole, benzimidazole, and edenine have been studied in the MeOH−HCl, MeOH, and AcOH systems. Compound 1 is a novel ferrocenylalkylating reagent which, unlike α-hydroxyalkylferrocenes, is capable of alkylating imidazole, benzimidazole (even in the absence of an acid catalyst), and adenine (regioselectively at the N(3) position). The antitumor activity discovered for ferrocenylalkylazoles of the type 1 may be attributed to the ability of such compounds to ferrocenylalkylate nucleic bases. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 172–174, January, 1997.     

Hyper-Wiener index for acyclic structures

The discriminating ability of the hyper-Wiener index (the ability to discriminate between isomers) is discussed on a class of acyclic structures (trees) including the molecular graphs of alkanes. For trees with 4 to 26 vertices, numerical data on the classes of trees with coincident indices were obtained. For classes with maximal power, the diagrams of the corresponding trees are presented. Using the index for processing chemical structural data is discussed. Translated fromZhurnal Strukturnoi Khimii, Vol. 40, No. 2, pp. 351–357, March–April, 1999.