Synthesis, characterization and antimicrobial evaluation of ferrocene-oxime ether benzyl 1H-1,2,3-triazole hybrids

A series of eight novel ferrocene-oxime ether benzyl 1H-1,2,3 triazole hybrids 5a-h were designed and synthesized by employing Cu(i) catalyzed azide-alkyne [3+2] cycloaddition (CuAAC) between ferrocenecarboxaldehyde oxime O-propargyl ether and benzyl azides. The alkyne, ferrocenecarboxaldehyde oxime O-propargyl ether 3, was synthesized by converting ferrocenecarboxaldehyde 1 into ferrocenecarboxaldehyde oxime 2 with subsequent O-propargylation. All the ferrocenyl triazole derivatives are remarkably stable crystalline solids and were obtained in good yields. All the products were well characterized by means of various analytical and spectroscopic techniques. The electrochemical behavior of the synthesized ferrocene-oxime ether benzyl triazole hybrids was investigated. Further, the structure of one of the triazoles 5a was unambiguously established by means of single-crystal X-ray diffraction study. All the triazole compounds have been screened for in vitro antimicrobial activity against two Gram-positive (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae), and one fungal (Candida albicans) microorganism. All the ferrocene-oxime ether benzyl 1H-1,2,3 triazole hybrids have shown moderate to good inhibitory activity against most of the tested bacterial and fungal strains in comparison with standard drugs.