Development of semi‐empirical electrotopological index using the atomic charge in QSPR/QSRR models for alcohols

Abstract

The semi-empirical electrotopological index (I SET ) used for quantitative structure-retention relationship (QSRR) models firstly developed for alkanes and alkenes, was remodeled for different organic compounds such as ketones, aldehydes and esters. In this study, the I SET was developed and optimized to describe the chromatographic retention of aliphatic alcohols on six different stationary phases (SE-30, OV-3, OV-7, OV-11, OV-17 and OV-25). The presence of a hydroxyl group leads to a charge redistribution increasing the interactions between these molecules and the stationary phases relative to the interactions between hydrocarbons and the same stationary phases. These considerations were included in the calculation of I SET . The simple linear regressions (SLR) between retention indices and the I SET for each stationary phase showed good statistical quality, high internal stability and good predictive ability for external groups, especially for stationary phases with low polarity. A single combined model, in which the McReynolds polarity term was added as a descriptor, was developed for all the data points for the stationary phases and the results were of satisfactory predictive quality. The efficiency and the applicability of the approach were demonstrated through the high quality quantitative structure-property relationship (QSPR) model for the boiling point (BP). For this physical property 134 compounds were used; most of them were not included in the original data set employed to develop the I SET .

Molecular Interactions in Chromatographic Retention: A Tool for QSRR/QSPR/QSAR Studies

“…Thus, it is clear that it is necessary to introduce an equivalent local dipole moment for each of the organic functions that participate in increasing the retention value. For alcohols, as in the case of ketones, aldehydes and esters, this was achieved by multiplying the SET i values of the atoms belonging to the C-OH group by a function A µ as defined by equation 4, with µ F being the equivalent local dipole moment which is dependent on the charges of the atoms belonging to the C-OH group (Souza et al, 2010). Clearly, µ F is directly related to the net atomic charge of the oxygen atoms since it must reflect some contribution to the electrostatic interaction between these atoms and the stationary phase.…”

“…The semi-empirical topological index (I ET ) allowed the creation of a new descriptor, the electrotopological index, I SET , which was recently developed by our group and applied to QSPR studies to predict the chromatographic retention index for a large number of organic compounds, including aliphatic hydrocarbons, alkanes and alkenes, aldehydes, ketones, esters and alcohols (Souza et al, , 2009a(Souza et al, , 2009b(Souza et al, , 2010. The new descriptor for the above series of molecules can be quickly calculated from the semi-empirical, quantum-chemical, AM1 method and correlated with the approximate numerical values attributed by the semiempirical topological index to the primary, secondary, tertiary and quaternary carbon atoms.…”

“…This new index, I SET , is able to distinguish between the cis-and trans-isomers directly from the values for the net atomic charges of the carbon atoms that are obtained from quantumchemical calculations . For polar molecules like aldehydes, ketones, esters and alcohols, the presence of heteroatoms like oxygen changes considerably the charge distribution of the corresponding hydrocarbons, leading to a small increase in the interactions between the solute and the stationary phase (Souza et al, 2009a(Souza et al, , 2009b(Souza et al, , 2010). An appropriate way to calculate the I SET was developed, taking into account the dipole moment exhibited by these molecules and the atomic charges of the heteroatoms and the carbon atoms attached to them.…”

Estimating the Octanol/Water Partition Coefficient for Aliphatic Organic Compounds Using Semi-Empirical Electrotopological Index

“…This new approach takes into account the charges of the heteroatom and the carbon atoms attached to them through the definition of an equivalent local dipole moment [23–26]. …”

A Quantitative Structure-Property Relationship (QSPR) Study of Aliphatic Alcohols by the Method of Dividing the Molecular Structure into Substructure

“…QSPR has received significant contributions from various research schools [ 3 – 8 ]. Various quantitative structure–property relationship (QSPR) models have been proposed for estimating the properties of a series of aliphatic alcohols [ 9 – 12 ].…”