Quantitative Structure Property Relationship (QSPR) Study For Oxygenates And Sulfur Compounds

Quantitative Structure Activity/Property Relationships (QSAR/QSPR) remain thefocus of many chemic studies aimed at the modeling and prediction of biological andphysicochemical properties of molecules. The basic task of QSAR/QSPR is to findoptimum quantitative relationships, which can then be used for the prediction of theproperties of molecular structures. And the performance of QSPR model mostlydepends on the parameters used to describe molecular structures.In the paper, a novel quantum toplogical index X was proposed for the reserchingof quantitative structure-retention relationship (QSRR) and the new index haddifinitional physicochemical meaning and easy to calculate. The novel quantumtoplogical index combined with Odd-Even Index (OEI), Molcular equlibrumelectronegativity(χeq)were used as structure descriptors to predict chromatographicretention indices (RI) on different polar stationary phases for thiols, The obtainedQSRR models showed high values of correlation coefficient (R＞0.97)andFisher-ratio statistics.In order to investigate the quantitative structure-retention relationship ofdisulfides compounds, the molecular structure was divided into two parts, R and X, toobtain molecular structure parameters. The topological indices: VertexDegree-distance Index (VDI), Odd-Even Index (OEI), the Total Topological StericEffect Index (TTSEI) and Polarization Effect Index (PEI) were extended and used topredict the chromatographic retention indices (RI) for disulfides compounds. Simplelinear regressions between the retention indices and molecular structural descriptorswere established. The correlation coefficients were larger than0.98. The performanceof the model was tested through cross-validation by the Leave-one-out procedure(LOO), showing good statistical parameters. Statistical analysis showed that thequantitative structure-retention relationship (QSRR) models had high internalstability and good predictive ability.A quantitative structure–property relationship (QSPR) analysis of aliphaticalcohols was presented. Four physicochemical properties were studied: Boiling point(BP), n-octanol–water partition coefficient (lg KOW), water solubility (lg W) and thechromatographic retention indices (RI) on different polar stationary phases. TheMolecular Polarizability Effect Index (MPEI) combined with Odd-Even Index (OEI), the Sum Eigenvalues of bond-connecting matrix (SX1CH) previously developed in ourteam, were used to predict the property of aliphatic alcohols. The sets of moleculardescriptors were derived directly from the structure of the compounds based on graphtheory. QSPR models were generated using only calculated descriptors and multiplelinear regression techniques. These QSPR models showed high values of multiplecorrelation coefficient (R>0.99) and Fisher-ratio statistics. The leave-one-outcross-validation demonstrated the final models to be statistically significant andreliable.The topological index: Steric Effect Index (SVij) and Eigenvalues ofbond-connecting matrix (SX1CH,SX1CC) were used to predict the boiling points andmolar refractions for a set of aliphatic aldehydes and ketones. Simple linearregressions between the polarity parameters and molecular structural descriptors wereestablished separately, showing good statistical parameters(R>0.99). Statisticalanalysis showed that the QSPR models have high internal stability and goodpredictive ability.