Green synthesis of novel pyrazole containing Schiff base derivatives as antibacterial agents on the bases of in-vitro and DFT

A series of pyrazole containing Schiff bases were synthesized, by the reaction of 3,5-dimethyl-1-phenylpyrazole-4-carboxaldehyde and the corresponding active amines under microwave irradiation. The structures of the synthesized compounds were established by spectroscopic data (FT-IR, 1H NMR, 13C NMR and ESI-MS) and elemental analyses. The anti-bacterial activity of these compounds were tested in vitro by the disc diffusion assay against two Gram-positive and two Gram-negative bacteria, and then the minimum inhibitory concentration using chloramphenicol as reference drug. All the molecules were modeled and optimized by using density functional theory, DFT/B3LYP method. Calculated descriptors, the lower unoccupied molecular orbital and the density were used to interpret the antibacterial activity of the compounds. The results showed that compound 3 is better inhibitor of both types of test bacteria as compared to chloramphenicol.