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

Abstract

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, 1 H NMR, 13 C 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.Pyrazole Schiff bases Chloramphenicol Antibacterial activity Density functional theory Minimum inhibitory concentration

Green Synthesis, Characterization, Antibacterial Activity of Heterocyclic Compounds from Chalcone on Basis of in vitro and Quantum Chemistry Calculation

“…The synthetic route of compounds is outlined in Scheme-I. The chemical structures of the synthesized compounds were established by spectroscopic (FT-IR, 1 H NMR, 13 C NMR, Mass) and elemental analyses.…”

“…IR absorption spectra were recorded on Shimadzu FTIR-8400s using KBr pellets in the range of 4000-400 cm -1 . 1 H and 13 C NMR spectra were recorded on Bruker-AVANCE-III 600 MHz spectrophotometer and TMS (tetramethylsilane) as an internal standard. The 1 H and Asian Journal of Chemistry; Vol.…”

“…26, No. 21 (2014), 7283-7288 13 C NMR chemical shifts were reported as parts per million (ppm) downfield from TMS. Mass spectra were recorded on EI-MS spectrometer.…”

Highly efficient, catalyst‐free, one‐pot, pseudo five‐component synthesis of novel pyrazoline‐containing Schiff bases, metal complexes formation and computational studies via DFT method

“…Recently, computational chemistry has become a chief tool for chemists to survey the calculated data of experimental results. The Density Functional Theory (DFT) method is one of the most important and accurate approached in running these theoretical calculations . Continuing our recent studies on the synthesis of pharmacologically interesting heterocyclic compounds and green chemistry protocols, we report a simple and highly efficient synthesis of novel pyrazoline‐containing Schiff bases by in situ generation of diamine (DHNE) from the reaction of 1,1‐bis(methylthio)‐2‐nitroethylene (BMTNE) and hydrazine, and its application for one‐pot condensation reaction with various aldehydes under catalyst‐free conditions in EtOH at room temperature (Scheme ).…”

“…The Density Functional Theory (DFT) method is one of the most important and accurate approached in running these theoretical calculations. [31][32][33][34][35][36] Continuing our recent studies on the synthesis of pharmacologically interesting heterocyclic compounds and green chemistry protocols, [37][38][39][40][41][42][43] we report a simple and highly efficient synthesis of novel pyrazoline-containing Schiff bases by in situ generation of diamine (DHNE) from the reaction of 1,1bis(methylthio)-2-nitroethylene (BMTNE) and hydrazine, and its application for one-pot condensation reaction with various aldehydes under catalyst-free conditions in EtOH at room temperature (Scheme 1). In another section, Job's method (the method of continuous variation) [44][45][46][47] was employed to determine the stoichiometry of the reaction of pyrazoline-containing Schiff base 4o as ligand and metal ions [Mn(OAc) 2 , Cu(OAc) 2 and Zn(OAc) 2 ].…”