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Modeling the semi‐empirical electrotopological index in QSPR studies for aldehydes and ketones
Author(s) -
Souza Érica Silva,
Kuhnen Carlos Alberto,
Junkes Berenice da Silva,
Yunes Rosendo Augusto,
Heinzen Vilma Edite Fonseca
Publication year - 2009
Publication title -
journal of chemometrics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.47
H-Index - 92
eISSN - 1099-128X
pISSN - 0886-9383
DOI - 10.1002/cem.1215
Subject(s) - chemistry , quantitative structure–activity relationship , dipole , partial charge , molecule , mulliken population analysis , chemical polarity , heteroatom , computational chemistry , kovats retention index , polar , moment (physics) , molecular descriptor , thermodynamics , organic chemistry , gas chromatography , stereochemistry , chromatography , ring (chemistry) , physics , classical mechanics , astronomy
The semi‐empirical electrotopological index, I SET , used for quantitative structure–retention relationship (QSRR) models firstly developed for alkanes and alkenes, was remodeled for organic functions such as ketones and aldehydes. The I SET values for hydrocarbons are calculated through the atomic charge values obtained from a Mulliken population analysis using the semi‐empirical AM1 method and their correlation with the SET i values attributed to the different types of carbon atoms according to experimental data. For ketones and aldehydes the interactions between the molecules and the stationary phase are slowly increased relative to the hydrocarbons, due to the charge redistribution that occurs in the presence of heteroatoms. For these polar molecules the increase in the interactions was included in the calculation of the I SET values through the dipole moment of the whole molecule and also through an equivalent local dipole moment related to the net charges of the atoms of the CO and HCO functional groups. Our findings show that the best definition of an equivalent local dipole moment is clearly dependent on the specific features of the charge distribution in the polar region of the molecules (e.g. ketones and aldehydes), which allows them to be distinguished. Thus, the QSRR models for 15 aldehydes and 42 ketones obtained using the remodeled I SET were of good quality as shown by the statistical parameters. The ability of this remodeled index to include charge distribution and structural details opens a new way to study the correlations between the molecular structure and retention indices in gas chromatography. Copyright © 2009 John Wiley & Sons, Ltd.