Fungicidal evaluation of substituted 4-(1,3,4-thiadiazol-2-yl) benzene-1,3-diols

Fungicidal properties of 4-(1,3,4-thiadiazol-2-yl)benzene-1,3-diols set under in vitro conditions against five phytopathogenic fungi have been evaluated. The substitution panel includes amino-, alkyl-, alkoxyl-, aryl- and heteroarylderivatives. The most active compound with the benzyl substituent exhibits fungistatic effects amounting to 90-100% with the concentration of 20 μg mL-1 against R. solani, similar to the standard fungicides. The derivatives with amine moiety generally display lower activity than other analogues. F. culmorum seems to be the most refractory fungus compared to studied compounds. The influence of substitution of C-5 at the constant fragment at C-2 of 1,3,4-thiadiazole ring on the antifungal effect is discussed. To explain differences in the activity the quantum-chemical calculations were made.