Synthesis and biological activities of 3,6-disubstituted-1,2,4-triazolo-1,3,4- thiadiazole derivatives

Twelve novel triazolothiadiazole derivatives were synthesized from 4-amino-5-substituted-4H-1,2,4-triazole-3-thiols with various aromatic carboxylic acids by cyclization in the presence of phosphorous oxychloride. All the newly synthesized compounds were characterized by FTIR, 1H NMR, mass spectroscopy and elemental analysis. The antimicrobial activities of the title compounds were examined by disc diffusion method against Escherichia coli, Staphylococcus aureus, Pyricularia oryzae and Rhizoctnia solani. The bioassay indicated all synthesized triazolothiadiazole derivatives possessed moderate to good antibacterial and antifungal activities against the tested organisms. Especially, compounds 2e and 2k exhibited excellent antibacterial and antifungal activities among these triazolothiadiazole derivatives.