Synthesis, characterization, solvatochromic, antioxidant and antibacterial activities investigation of 2,2'-((1E,1'E)-((1,2,5-oxadiazole-3,4-diyl)bis (azanylylidene))bis(methanylylidene))bis(4-(phenyldiazenyl)phenol)

The azo-azomethine dyes 2-[(4-amino-1,2,5-oxadiazol-3-ylimino)methyl)-4-(phenyl diazenyl]phenol (2a-h) have been synthesized from the condensation reaction of  3,4-diamino -1,2,5-oxadiazole with 2-hydroxy-5-[(E)-(aryldiazenyl)]benzaldehyde(1a-h) in methanol. The structures of dyes have been characterized by elemental analysis, mass, IR, UV-Vis, ¹H and ¹³С NMR spectroscopy. UV–Vis absorption spectra indicated enol–keto tautomeric and positive solvatochromism in compounds 2a-h which is dependent on the substitution, solvent, pH and environment temperature. The synthesized compounds were investigated for their in vitro antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Compounds substituted with electron donating groups, such as, alkyl and methoxy groups showed moderate to mild antioxidant activity. The in-vitro antibacterial activity of all compounds was determined by disc diffusion method. The tested compounds showed varying degree of inhibition against B. cereus and S. aureus strains. However, E.coli and K. pneumonia were not sensitive to any of the tested samples.