The support vector machine (SVM), as a novel type of learning machine, was used to develop a Quantitative Structure-Property Relationship (QSPR) model of the O-H bond dissociation energy (BDE) of 78 substituted phenols. The six descriptors calculated solely from the molecular structures of compounds selected by forward stepwise regression were used as inputs for the SVM model. The root-mean-squ...

In order to accurately simulate C NMR spectra of hydroxy, polyhydroxy and methoxy substituted flavonoid a quantitative structure–property relationship (QSPR) model, relating atom-based calculated descriptors to C NMR chemical shifts (ppm, TMS = 0), is developed. A dataset consisting of 50 flavonoid derivatives was employed for the present analysis. A set of 417 topological, geometrical, and ele...

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. Th...

The use of descriptors based on local properties calculated at the molecular surface for QSPR models is discussed. It is suggested that descriptors should be related to the physical theory of intermolecular interactions and the relationship between established surface-based descriptors and the fundamental types of intermolecular interaction is discussed. Descriptors based on local properties th...

Relative centricity RC values of vertices/atoms are calculated within the Distance Detour and Cluj-Distance criteria on their corresponding Shell transforms. The vertex RC distribution in a molecular graph gives atom equivalence classes, useful in interpretation of NMR spectra. Timed by vertex valences, RC provides a new index, called Centric Connectivity CC, which can be useful in the topologi...

tant molecular property, playing a large role in the behavior of compounds in many areas of interest. Given the importance of solubility, a means of prediction based solely on molecular structure should prove a useful tool, as many compounds exist for which the solubility simply is not available. The solubility of chemicals and drugs in the water phase has an essential influence on the extent o...

A data set of 181 diverse anionic surfactants has been investigated to relate the logarithm of critical micelle concentration (cmc) to the molecular structure using Comprehensive Descriptors for Structural and Statistical Analysis (CODESSA Pro) software. A fragment approach provided superior quantitative structure-property relationship (QSPR) models in terms of statistical characteristics and p...

The nature and origin of a fundamental quantum QSPR (QQSPR) equation are discussed. In principle, as any molecular structure can be associated to quantum mechanical density functions (DF), a molecular set can be reconstructed as a quantum multimolecular polyhedron (QMP), whose vertices are formed by each molecular DF. According to QQSPR theory, complicated kinds of molecular properties, like bi...

Sign change problem (SCP) in multivariate Quantitative Structure-Activity/Property Relationships (QSAR/QSPR) is the inconsistency in the direction of association between molecular descriptors and the dependent variable. Sign change is observed when the signs of the elements of the reference vector (correlation vector for the data set obtained from variable selection) are compared to the signs o...