Synthesis and Characterization of 4-(E)-2-Hydroxy-4-methoxybenzylidene)amino-1, 5-dimethyl-2-phenyl-1, 2-dihydro-3H-pyrazol-3-one

Thesynthesismethodof 4-(E)-2-hydroxy-4-methoxybenzylidene)amino-1,5-dimethyl-2-phenyl-1, 2-dihydro-3H-pyrazol-3-one by the reaction of 2-hydroxy-4-methoxybenzaldehyde and 4-aminoantipyrine was studied. The maximum yield was 84% obtained under the molar ratio 1:1.75 of 2-hydroxy-4-methoxybenzaldehyde and 4-aminoantipyrine at temperature of 70℃ for 3.5 h. The molecular and crystal structure of the product was characterized by UV-vis, IR, ¹H NMR and X-ray single crystal diffraction. The results show that the object compound crystallizes in the monoclinic system, space group C2/c with a=30.827(6) Å, b=6.967 5(13) Å, c=16.978(4) Å, β=110.786(2)°, V=3 409.4(11) ų, D_c=1.315 g·cm^-3, Z=8, F(000)=1 424, μ=0.091 mm^-1, R₁=0.068 6, wR₂=0.171 1; the structure of the object compound features a stable crystal structure constructed by intramolecular hydrogen bond O₂-H2…N1, C(8)-H(8A)…O(3). It was a mild antioxidant, IC₅₀ was 2.10 mg·mL^-1, DPPH free radical scavenging activity was 5.11% under the concentration of 200 mg·mL^-1 of the object compound; the object compound has mild antibacterial activity against Staphylococcus aureus; minimal inhibitory concentration (MIC) was 1.0×10^-5 mol·L-1; but had no antibacterial activity against Pseudomonas aeruginosa and Escherichia coli.