QSPR study on the aqueous solubility (-IgSw) and n-Octanol/water partition coefficients (IgKow) of polychlorinated dibenzo-p-dioxins (PCDDs)

Optimized calculation of 75 Polychlorinated Dibenzo-p-dioxins (PCDDs) and their parent compound DD was carried out at B3LYP/6-31G* level with GAUSSIAN 98 program. The structural parameters identified with the Theoretical Linear Solvation Energy Relationship (TLSER) model were employed as theoretical descriptors in the Quantitative Structure-Property Relationship (QSPR) models derived to predict the aqueous solubility (-1gS(w)) and n-octanol/water partition coefficients (IgK(ow)) of PCDDs. The regression model obtained to predict -1gS(w) contains only one variable: the mean molecular polarizability (a). The best fitted equation for the correlation between -IgS(w) and a of 12 PCDDs was -1gS(w) = - 3.6425 + 0.0693a with r(3) as 0.9776, Standard Deviation (SD) as 0.30, and suggesting high accuracy of the - 1gS(w) predicting model. At the same time, there exists high correlation (r(3) = 0.8862) between n-octanol/water partition coefficients (1gK(ow)) and the mean molecular polarizability (alpha), and the SD is small. The mean molecular polarizability (alpha) is the only theoretical descriptor used in the QSPR model derived to predict 1gK(ow).