Quantitative structure–chromatographic retention relationship for polycyclic aromatic sulfur heterocycles

Polycyclic aromatic sulfur heterocycles (PASHs) are of concern in petroleum geochemistry and environmental chemistry. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 114 PASHs reported previously at the HF/6-31G* level of theory. A group of 25 statistically based parameters have been extracted. Linear relationships between gas-chromatographic retention index (RI) and the structural descriptors have been established by stepwise linear regression analysis. The result shows that two quantities derived from positive electrostatic potential on molecular surface, Vs+¯ (the average value of the positive electrostatic potentials on molecular surface) and σ+2 (a measure of dispersion tendency of positive electrostatic potential), together with Vmc (the molecular volume) and EHOMO (the energy of the highest occupied molecular orbital) can be well used to express the quantitative structure–retention relationship (QSRR) of PASHs. Predictive capability of the model has been demonstrated by leave-one-out cross-validation with the cross-validated correlation coefficient (RCV) of 0.992. Furthermore, when splitting the 114 PASH samples into calibration and test sets in the ratio of 2:1, a similar treatment yields an equation of almost equal statistical quality and very similar regression coefficients, validating the robustness of our model. Predictions for six PASHs from other source have also been made. The QSRR model established may provide a new powerful method for predicting chromatographic properties of aromatic organosulfur compounds.