Synthesis and evaluation of in vitro antibacterial and antioxidant activity of 4-((3-formyl-4-hydroxyphenyl) diazenyl)-alkylpyridinium derivatives

Monoazo compounds, which have the common structure unit of the azo chromophore, - N=N-, linking two aromatic systems.Delocalizedintegratedπ-orbitals systems in aryl azo compounds causes theappearance ofbright colorsfromyellowto red. According to thenontoxicity, thiscompounds use inpainting, biologyand medicalstudies. The pharmaceutical importance of compounds including an arylazo group has been extensively reported in the literature [1]. Also, azo dyes are reported to have a broad range of antibacterial, antifungal, antitumor and anti-oxidant activities [2, 3]. The simple reaction of 2-hydroxy-5-(pyridin-4-yldiazenyl) benzaldehyde (A) with n-alkyl bromides generated five novel azo pyridinium salts in good to excellent yields. The UV-Vis absorption spectra of synthesized compounds indicated enol–keto tautomeric, solvatochromism and cis-trans isomerization. The solvatochromism behavior of compounds due to intramolecular hydrogen bond in enol–keto tautomeric, dipole moment changes and depends on the substitution, solvent, pH and temperature. Antibacterial activity was studied by disc diffusion and MIC methods. Diphenylpicrylhydrazyl (DPPH) assay was used to determine the antio-xidant property.