Synthesis, Antimicrobial and Antioxidant Activity of Some New Pyrazolines Containing Azo Linkages

Pyrazolines and azo-pyrazolines are influential groups of heterocyclic compounds with two nitrogen atoms inside the five-membered ring. They play an important role in a wide range of biological processes, such as antifungal, antioxidant, antimalarial and other antimicrobial activities.

The main objective of this study is to synthesize some new heterocyclic compounds with antioxidant and antimicrobial activity Methods: One-pot three components and traditional synthesis of new azo-pyrazoline compounds were achieved in this work. The preparation process has been started by diazotizing 4-(6-methylbenzothiazol-2-yl) benzamine and its coupling reaction with 4-hydroxy acetophenone producing azo-acetophenone, followed by benzylation with benzyl chloride to form the starting material, azo-benzyloxy acetophenone. A series of substituted benzaldehydes were reacted with the latter compound via one pot and classical methods, forming new chalcones containing azo linkages and benzyloxy moieties, which were then converted into new target azo-pyrazoline derivatives.

The structures of the synthesized compounds were confirmed by spectroscopic techniques using FT-IR, ¹H-NMR, ¹³C-NMR, and ¹³C- DEPT- 135 spectra. Finally, the synthesized compounds were screened for their antioxidant and antimicrobial activities against Staphylococcus aureus and Escherichia coli.

Overall, the one-pot three-component synthesis of pyrazoline compounds generally provides advantages in terms of efficiency, simplicity, and time-consumption compared to classical synthesis methods. Hence, the study advocates the one-pot method because it eliminates the tedious process of making chalcones, which takes time, materials, and unnecessary effort. Therefore, this is the most convenient and effective approach to green chemistry.