Using PM3 Hamiltonian, factor analysis and regression analysis in developing quantitative structure-property relationships for photohydrolysis quantum yields of substituted aromatic halides

Based on the descriptors computed by the PM3 hamiltonian and the application of factor analysis and multiple regression analysis, several Quantitative Structure-Property Relationship (QSPR) equations for disappearance quantum yields of 45 substituted halogen compounds were obtained. After the exclusion of the outliers, the remaining two QSPR equations can be used to predict disappearance quantum yields for compounds with similar structure. By stepwise variable selection regression analysis, two significant factors relating to the disappearance quantum yields of the compounds were identified: the energy of the lowest unoccupied molecular orbital and the electron-nuclear attraction energy of the two-center term for carbon-halogen bonds. By factor analysis, other factors that may relate to the quantum yields of the compounds were obtained. The quantum chemical descriptors used in the study can be determined by calculation from any given structural formula. So the method used in this study permits near a priori prediction of environmental properties for compounds for which the empirical parameters are not readily available.