Quantitative Structure Activity Relationships for the Antifungal Activity of O, O-Diaryl O-2-Chloroethyl Phosphorothionates*

The relationship between the structure of a series of O, O-diaryl O-2-chloroethyl phosphorothionates and their fungicidal activity against Rhizoctonia solani and Sclerotium rolfsii was analysed using physico-chemical parameters of the compounds by means of multiple regression analysis. The QSAR model have revealed that the electron donating groups in the benzene ring and a high value of π, hydrophobic parameter whether positive or negative are important in imparting high fungicidal activity against R. solani whereas shape of the para substituents as determined by high and low value of STERIMOL length [ΣL(p) and width [ΣB4(p)] parameters respectively and low value of hydrophobic parameter, R_M are favourable for the fungicidal activity of compounds in this series against S. rolfsii.