Synthesis and biological activities of 3,6-disubstituted-1,2,4-triazolo(3,4-b)-1,3, 4-thiadiazoles

4-Amino-5aryl/heteroaryl substituted 3-mercapto-1,2,4-triazoles, have been prepared from the corresponding aromatic carboxylic acid through a multistep sequence. These trizoles have been made to react with various aromatic acids to yield 3,6-disubstituted-1,2,4-triazole{3,4-b}-1,3,4 thiadiazoles. Elemental analysis IR, 1H NMR and mass spectral data has elucidated the structures of all newly synthesized compounds. These compounds have shown significant pharmacological activities and are found to be highly active against various fungi and bacteria