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U Maran

Publications and source records attributed to U Maran.

6 recordsLinked to original sources
PubMed2000

QSPR correlation and predictions of GC retention indexes for methyl-branched hydrocarbons produced by insects.

A successful interpretation of the complex manner by which the GC retention indexes of methylalkanes produced by insects are related to chemical structure was achieved using the quantitative structure-property relationship (QSPR) method. A general QSPR model including mainly topological descriptors was obtained for 178 data points. The error of the model is similar to the experimental error. The model was supported by (i) leave-one-out cross validation and (ii) division into three sets and prediction of each set from the other two. As a further test of the utility of the model, retention indexes were successfully predicted for an external set of 30 methyl-branched hydrocarbons not involved in the deduction of the correction equation from the main data set. General trends of the structural variation of compounds in any given range of retention index are discussed. The average error was 4.6 overall and 4.3 for the 165 compounds remaining after leaving out small monomethyl alkanes.

Alkanes↗
PubMed1991

About the mutagenicity of chlorine-substituted furanones and halopropenals. A QSAR study using molecular orbital indices.

Electron affinities, frontier molecular orbital energies and electron densities at individual carbon atoms were calculated for 11 chlorofuranones including the strong mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) and for 5 halopropenals by semi-empirical AM1 and ab initio STO-3G methods. Significant correlations were found between Ames TA100 mutagenicity and the following AM1 electronic parameters of chlorofuranones: electron affinity (r = 0.9556). LUMO energy (r = 0.9332) and frontier electron density of LUMO at the alpha-carbon (r = 0.8882). In halopropenals only LUMO electron density at the beta-carbon correlates well with mutagenicity. The observed correlations suggest a reaction mechanism in which chlorofuranones and halopropenals act as electron acceptors in the interaction with DNA.

Aldehydes↗
PubMedDate not supplied

Correlation of the solubilities of gases and vapors in methanol and ethanol with their molecular structures.

Two four-parameter quantitative structure-property relations, with R2 = 0.95 and R2 = 0.97, respectively, gave good correlations for the solubilities of 87 gases and vapors in methanol and 61 in ethanol. All the descriptors used are derived solely from the structures of the molecules, making it possible to predict solubilities for unavailable or unknown compounds.

Journal Article↗
PubMedDate not supplied

Interpretation of quantitative structure-property and -activity relationships.

The potential utility of data reduction methods (e.g. principal component analysis) for the analysis of matrices assembled from the related properties of large sets of compounds is discussed by reference to results obtained from solvent polarity scales, ongoing work on solubilities and sweetness properties, and proposed general treatments of toxicities and gas chromatographic retention indices.

Chemical Phenomena↗
PubMedDate not supplied

Theoretical descriptors for the correlation of aquatic toxicity of environmental pollutants by quantitative structure-toxicity relationships.

Quantitative structure-toxicity relationships were developed for the prediction of aqueous toxicities for Poecilia reticulata (guppy) using the CODESSA treatment. A two-parameter correlation was found for class 1 toxins with R(2) = 0.96, and a five-parameter correlation was found for class 2 toxins with R(2) = 0.92. A five-parameter correlation for class 3 toxins had R(2) = 0.85. The correlations for class 4 toxins were less satisfactory. All the descriptors utilized are calculated solely from the structures of the molecules, which makes it possible to predict unavailable or unknown toxins.

Animals↗