Synthesis, spectral studies, antioxidant and antibacterial evaluation of aromatic nitro and halogenated tetradentate Schiff bases

Herein, we report the synthesis, characterization, and biological properties of eleven (3a-3k) novel Schiff bases. The spectral data of FT-IR, 1H NMR, 13C NMR, and LC-MS are associated with these synthesized compounds. From the FT-IR analysis, we confirmed the azomethine (-C=N-) group and from 1H NMR data, the phenolic –OH proton is appeared at range δ 13.92–14.09ppm due to hydrogen bonding. The LC-MS analysis agreed with molecular ion peaks of synthesized Schiff bases. To evaluate the antibacterial activity of newly synthesized compounds were screened against b. licheniformis, b. species, e. coli, and s. aureus. Furthermore, the antioxidant activity was investigated by two methods 2,2-diphenyl-1-picryl hydrazyl (DPPH) and hydroxyl radical scavenging methods. The (-NO2,-Cl,-Br,-I) substituted compounds have shown good antibacterial activity against tested organisms. Also, these compounds were exhibited higher antioxidant activity by given methods.