Efficacy of organophosphorus derivatives containing substituted chalcone thiosemicarbazones and dithiocarbazates against fungal pathogens of sugarcane

Ten novel organophosphorus derivatives have been prepared by the reactions of 0,O-diethylchlorophosphate with two important series of substituted chalcones viz., substituted chalcone thiosemicarbazones and substituted chalcone dithiocarbazates. The derivatives have been characterized on the basis of analysis and spectral (IR, H-1 NMR) data. Fungicidal activity of these derivatives against Colletotrichum falcatum, Fusarium oxysporum and Curvularia pallescens have been evaluated. The screening results have been correlated with the structural features of the tested compounds. Organophosphorus derivatives containing 2,2'-dihydroxybenzalacetophenone thiosemicarbazone, 2-chlorobenzal-2'-hydroxyacetophenone thiosemicarbazone, 2-chlorobenzal-2'-hydroxy acetophenone-S-benzyl-dithiocarbazate proved more active than some prevalent commercial synthetic fungicides.