Spectroscopic and solvatochromism studies along with antioxidant and antibacterial activities investigation of 2-((2-mercaptophenylimino)methyl)-4-(phenyldiazenyl)phenol

• The aminothiophenole based azo–azomethine dyes have synthesized.
• The tautomerism equilibrium between azo and hydrazone forms in organic solvent was studied.
• The solvatochromism is dependent on the substitution, solvent, pH and temperature.
• The effect of dipole moment on enol–keto tautomerism of azo–azomethine dyes.
• The antibacterial activity of azo–azomethine dyes increased with electron releasing of substituents.

The condensation reaction of 2-hydroxy-5-(aryldiazenyl)benzaldehyde (1a–d) with 2-aminothiophenole affored Schiff base compounds 2-((2-mercaptophenylimino)methyl-4-(-aryldiazenyl)phenol (2a–d). The structures of compounds (2a–d) were characterized by elemental analysis, mass, infrared, UV–vis and NMR spectroscopy. The 2a–d shows enol–keto tautomeric and positive solvatochromism. The antibacterial activities of 2a–d were also evaluated by disc diffusion method. Compound 2b displayed activity against Staphylococcus aureus and Bacillus cereus, 2a and 2c were active against B. cereus but 2d did not exhibit activity against the tested organisms. Among the tested compounds, 2b showed the best antioxidant properties as evaluated by free radical scavenging activity on 1,1-diphenyl-2-picryl-hydrazyl and ferric reducing power determination.

New azo–azomethine dyes were prepared via condensation reaction of 2-aminothiophenol with azo couled 2-hydroxy-5-(aryldiazenyl)benzaldehyde. The UV–vis spectra indicated positive solvatochromism in synthesized compound are dependent on the substitution, solvent, pH and temperature. Some compounds exhibited antibacterial or antioxidant activities.Figure optionsDownload as PowerPoint slide