Design, Synthesis, Characterization And Antifungal Activity Research Of Heterocyclic Chalcone Thiosemicarbazone And Semicarbazone Derivatives

In accordance with the principle of connecting bioactive substructures together, two new series of thiosemicarbazone and semicarbazone derivatives?thirty compounds? were designed and synthesized using heterocyclic chalcones as lead compounds and by connecting them with thiosemicarbazide and semicarbazide respectively. Among them, twelve compounds were thiosemicarbazone derivatives?1a-1l? and eighteen compounds were semicarbazone derivatives?2a-2r?. The structure of these compounds was characterized by NMR(¹H NMR and ¹³ C NMR). Additionally, the single crystal of compound 1g was cultured and its structure was determined by single crystal X-ray diffraction. The results showed it crystallizes in the monoclinic system with space group P21/c. The unit cell parameters are a = 7.5119?4? ?, b =15.7255?9? ?, c = 13.5319?6? ?, a = 90.00°, b = 90.394?5?°, g = 90.00°. At the same time, the antifungal activity of the thirty synthesized compounds was screened against six plant pathogenic fungi namely Rhizoctonia solani, Gibberella zeae, Helminthosporium maydis,Botrytis cinerea, Coniothyrium diplodiella and Coniothyrium lagenarium using carbendazim as the comparative standard by the plate growth rate method. The results were as follows:?1? The twelve compounds of the first series all displayed good antifungal activity. Among them, the inhibitory rate of compound 1f against Gibberella zeae, Helminthosporium maydis, Botrytis cinerea, Coniothyrium diplodiella and Coniothyrium lagenarium reached above 70% at 100 mg/L. The inhibitory rate of compounds 1e and 1g against four of the six fungi also reached above 70% at 100 mg/L. The results of the relationship between concentration and efficacy exhibited that they all possessed significant correlations.?2? For the compounds of the second series, the inhibitory rate of seven compounds of them against one of the six fungi reached more than 70% at 100 mg/L. Among them, compound2 l displayed the best activity and its antifungal activity against Coniothyrium lagenarium surpassed 85% at 100 mg/L. These compounds also showed significant correlations between concentration and efficacy.