Synthesis, antioxidant, and antimicrobial activity of some novel N-substituted derivatives of 3-(benzo[b]thiophen-2-yl)-5-(3-[trifluoromethyl]styryl)-4,5-dihydro-1H-pyrazole

The new series of various N-substituted pyrazoline derivatives containing benzo[b]thiophene and styryl with trifluoromethyl substitution at meta- position were synthesized. Compound 1-(3-(benzo[b]thiophen-2-yl)-5-(3-[trifluoromethyl]styryl)-4,5-dihydro-1H-pyrazol-1-yl)-2-chloroethan-1-one (3b) was further substituted with various thiols. The structures of newly synthesized compounds were characterized by UV, IR, NMR, and Mass and had been screened for antioxidant and antimicrobial activity. The in vitro antioxidant screening revealed that hydroxyl radical scavenging (HRS) activities of compounds 3a, 3b, 3c, 3f, 3i, 3j, 4a, and 4c are stronger than the other compounds and the in vitro antimicrobial activities of the compounds were tested against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis, Aspergillus flavus, and Aspergillus Niger. The compounds 3d and 3e exhibit good activity against P. mirabilis. Compounds 3a, 3b, 3c, 3 h, 3i, 3j, and 4a showed significant activity against S. aureus. Compounds 3e and 3f showed very good activity against A. flavus. Compounds 3e, 3f, and 4c showed good activity against A. Niger.