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-(1H-imidazole-1-yl)benzaldehyde and 4-(1H-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-(1H-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)ImpClPh), 4(5)-imidazolecarboxaldehyde-para-nitrobenzoyl hydrazone (4(5)ImpNO2Ph), 4-(imidazole-1-yl)acetophenone-para-chloro-benzoyl hydrazone (4ImAcpClPh) and 4-(imidazole-1-yl)acetophenone-para-nitro-benzoylhydrazone (4ImAcpNO2Ph) were highly active against Candida glabrata. 4(5)ImpClPh and 4(5)ImpNO2Ph were very effective against C. cladosporioides. In many cases, activity was superior to that of the reference compound nystatin.