The new Schiff bases of 2-alkylthio-5-(4-aminophenyl)-1,3,4-oxadiazoles and their antimicrobial activity

By the reaction of 5-(4-aminophenyl)-1,3,4-oxadiazolin-2-thione with alkyl halides 2-alkylthio-5-(4-aminophenyl)-1,3,4-oxadiazoles, 2-4 were obtained. By the reaction of compounds 2-4 with aromatic aldehydes, new Schiff bases 5a-d and 6a-d were synthesized. The structures of synthesized compounds are confirmed by the IR, UV, H-1 NMR for all compounds, C-13 NMR for compounds 3, 4, 5a-5d, 6a, 6d and X-ray for compound 3. All substances were tested in vitro for their antibacterial and antifungal activity. The results showed that Compound 2 exhibited remarkable activity against Candida albicans. Compounds 5a-d were found to exhibit a weak selective activity against Gram-positive bacteria of Bacillus subtilis and compounds 6a-d against Gram-negative bacteria of Escherichia coli.