Structural Studies and Investigation on the Activity of Imidazole-Derived Thiosemicarbazones and Hydrazones against Crop-Related Fungi

New imidazole derived thiosemicarbazones and hydrazones were prepared by condensation of 4(5)-imidazole carboxaldehyde, 4-(1 H-imidazole-1-yl)benzaldehyde and 4-(1 H-imidazole-1-yl)acetophenone with a thiosemicarbazide or hydrazide. All compounds were characterized by quantitative elemental analysis, IR and NMR techniques. Eight structures were determined by single crystal X-ray diffraction. The antifungal activities of the compounds were evaluated. None of the compounds exhibited significant activity against Aspergillus flavus and Candida albicans, while 4(5)-imidazolecarboxaldehyde thiosemicarbazone (ImT) and 4-(1 H-imidazole-1-yl)benzaldehyde thiosemicabazone (4ImBzT) were highly and selectively active against Cladosporium cladosporioides. 4(5)-Imidazolecarboxaldehyde benzoyl hydrazone (4(5)ImPh), 4(5)-imidazolecarboxaldehyde- para-chlorobenzoyl hydrazone (4(5)Im pClPh), 4(5)-imidazolecarboxaldehyde- para-nitrobenzoyl hydrazone (4(5)Im pNO 2Ph), 4-(imidazole-1-yl)acetophenone- para-chloro-benzoyl hydrazone (4ImAc pClPh) and 4-(imidazole-1-yl)acetophenone- para-nitro-benzoylhydrazone (4ImAc pNO 2Ph) were highly active against Candida glabrata. 4(5)Im pClPh and 4(5)Im pNO 2Ph were very effective against C. cladosporioides. In many cases, activity was superior to that of the reference compound nystatin.