Predicting Ah Receptor Binding Data of PCDFs Using Quantum Chemical Method(2): Grey Relationship Analysis of Invariables

To elucidate the relationship between the Ah receptor binding affinity and molecular structures of PCDFs, grey relationship analysis approach was introduced. The magnitudes of twelve quantum chemical parameters as well as a derived parameter is calculated from the view of their effects on the Ah receptor binding affinity. The physical meanings of variables were considered for the result analysis. Three parameters of largest magnitudes were obtained, namely, the energy of lowest unoccupied molecular orbit(E_(lumo)), the electrophilic superdelocalizability (S_r~E) and the average molecular polarizability(α). It means the potential of electron reception has the most important effect on the Ah receptor binding affinity. With the increase of chlorine atom number in the molecular, E_(lumo) and S_r~E decreases, whic means the molecular becomes more intensive to get electron and to be reduced. At the same time, α increases, which means the molecular has larger affinity for electrons and stronger force on the receptor. Those factors caused the increasing trend of Ah receptor binding affinity.