Schiff Bases Derived from 2‐Amino‐6‐methylbenzothiazole, 2‐Amino‐5‐chloropyridine and 4‐Chlorobenzaldehyde: Structure, Computational Studies and Evaluation of Biological Activity

Abstract

Molecular structure of (E)‐N‐(4‐chlorobenzylidene)‐6‐methylbenzo[d]thiazol‐2‐amine, (E)‐N‐(4‐chlorobenzylidene)‐5‐chloropyridin‐2‐amine was determined in solution and solid states by various techniques such as UV/Vis, FT‐IR, NMR spectroscopy, HRMS and X‐ray diffraction. Both the Schiff base compounds crystallize as monoclinic system with identical space group P21/c. Supramolecular interactions observed in X‐ray structure are validated via density functional theory (DFT) calculations. Further, the reactivities of both compounds (ligands) are analysed with the help of frontier molecular orbitals (FMOs) analysis. They were treated with Cu and Ag salts to obtain corresponding coordination complexes. Both the ligands contain three possible coordination sites namely, endocyclic nitrogen, sulfur and the imine nitrogen. Among these nucleophilic centres, imine nitrogen is more basic and readily coordinates with Cu and Ag metals. The compounds were tested for their fluorescence properties and all the compounds were found to be fluorescence active. The Schiff base ligands and their complexes were also tested for preliminary biological activities such as antibacterial, antioxidant and enzyme inhibition. Molecular docking studies were implemented to compare and validate the enzyme inhibition potentials of ligands. Moderate activities were observed for all compounds. The activities of ligands enhanced by complexation with Cu(II) and Ag(I) metals ions.

Supramolecular Assemblies of 3/4-Chlorobenzoic Acid and Amino-Chloropyridine Derivatives: Synthesis, X-ray Diffraction, DFT Calculations, and Biological Screening

“…These values reflect the semiconductor behavior of these compounds, along with high chemical and kinetic stabilities. The same type of behavior was noticed in compounds recently reported in [57]. Electronic density distributions illustrate that in compounds 1a and 1b, the HOMO densities reside on the chloro-group of the 3-chlorobenzoic acid fragment and its nearest carbon (Figure 10).…”

“…The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the antioxidant potential (free radical scavenging activity) of the prepared materials and the respective pure starting materials [57]. Samples of about 20 µL and a DPPH reagent volume of 180 µL were loaded into microplate wells.…”

New N4-Donor Ligands as Supramolecular Guests for DNA and RNA: Synthesis, Structural Characterization, In Silico, Spectrophotometric and Antimicrobial Studies

“…In the case of the Ag(I) polymer, the coordination was evidenced by the shifts of the c, d, and e proton signals compared to the parent spectrum of L1 ( Figure S12 ). In the literature, there are some reports on the decomposition of Schiff bases upon the addition of metal salt [ 34 ], but in the case of our acyclic and macrocyclic Schiff bases, our experimental results indicated that they were highly stable [ 11 , 35 , 36 , 37 ].…”

Benzimidazol‐1‐yl‐1‐phenylpropanone Analogs as Potent Antimicrobial Agents: Rational Design and Synthesis

“…Moreover, some of the Schiff bases were also explored and have been reported to carry the notable therapeutic profile [9] . Research disciplines are extensively flooded with a myriad of medicinal properties for instance, anti‐cancer [10] anti‐microbial [11] analgesic [12] etc. The synthetic scheme to attain Schiff base includes condensation of aromatic aldehydes or ketones with primary amines in presence of alcohol by the aid of reflux assembly [13] …”