Characterization, DFT, and antimicrobial evaluation of some new N₂O₂ tetradentate Schiff base metal complexes

Abstract

Fe (III), Co (II), Ni (II), Cu (II), Y (III), Zr (IV), La (III), and U (VI) interact with Gat‐o‐phdn Schiff base (4E,4′E)‐4,4′‐(1,2‐phenylenebis (azaneylylidene))bis(1‐cyclopropyl‐6‐fluoro‐8‐methoxy‐7‐(3‐methylpiperazin‐1‐yl)‐1,4‐dihydroquinoline‐3‐carboxylic acid to produce cationic mononuclear complexes. The isolated solid complexes were characterized with physicochemical, spectroscopic techniques (FT‐IR, UV–Vis and 1H NMR), mass spectrometry, and thermogravimetric analyses. The infrared data indicated that Gat‐o‐phdn acting as tetradentate ligand chelated to the metal ions through the carboxylate oxygen and the nitrogen of azomethine group. The metal ions complete the coordination number with water molecules. The mechanism of the thermal decomposition was detected, and the kinetic parameters of the dissociation steps were evaluated using Coats–Redfern (CR) and Horowitz–Metzger (HM) methods. Bond lengths, bond angles, total energy, heat of formation, dipole moment, and the lowest energy model structures have been determined using density functional theory (DFT) calculations. The synthesized ligand and its complexes were screened for antimicrobial activities against two Gram‐positive bacteria, two Gram‐negative bacteria, and two fungi. The Cu (II) complex was very highly significant against Staphylococcus aureus compared with free Gat‐o‐phdn and references standard control. Also, it showed the highest antibacterial effects compared with all complexes.

Novel Enrofloxacin Schiff Base Metal Complexes: Synthesis, Spectroscopic Characterization, Computational Simulation and Antimicrobial Investigation against Some Food and Phyto-Pathogens

“…25, 88.37, 14.67, 89.12 Ω −l mol −1 cm 2 , respectively. These data clearly showed the chelates of Fe(III), Y(III) and La(III) were ionic in character and electrolytes, while the Zr(IV) complex was a non-electrolyte [15,16,19].…”

“…In the literature survey there is not any study on the enrofloxacin Schiff base. With the continuing interest in the chemistry of the potentially useful Schiff base generated from fluoroquinolone that have biological action [16][17][18], the aim of the current research was to study the effect of changing atomic radii, atomic mass, or oxidation state of Fe(III), Y(III), Zr(IV) and La(III) with Cl − as a counter ion on the efficacy or stability of the biological properties of enrofloxacin as antibacterial agent in its new form as a H 2 Erx-en Schiff base (Scheme 1) to determine the target sites of novel synthesized complexes at the bacterial cells. The resulting complexes were characterized using elemental analyses, molar conductivity, magnetic susceptibility assessments, FT-IR, UV-Vis, 1 HNMR, mass spectra, and thermal behavior and DFT.…”

Comments on multiple publications reporting single heating rate kinetics

“…The purpose of this note is to alert the Applied Organometallic Chemistry community to an alarming number of publications that report the single heating rate kinetics for thermal decomposition of compounds. According to Scopus, [ 1 ] most recently (i.e., in the years 2021 and 2022) this journal published 21 papers [ 2–22 ] that study the thermal decomposition kinetics as measured by thermogravimetry at a single heating rate. The resulting measurements are treated by means of the Coats–Redfern [ 23 ] or Horowitz–Metzger [ 24 ] method in order to evaluate the kinetic parameters, that is, the activation energy, E, preexponential factor, A, and reaction model, g(α) .…”

Synthesis, Spectral Characterization, Thermal Investigation, Computational Studies, Molecular Docking, and In Vitro Biological Activities of a New Schiff Base Derived from 2-Chloro Benzaldehyde and 3,3′-Dimethyl-[1,1′-biphenyl]-4,4′-diamine

“…Schiff bases are nitrogen analogs of aldehydes and ketones, with imine or azomethine groups replacing the carbonyl group (CO). Schiff bases are used in closure, cycloaddition, and replacement to synthesize several beneficial compounds for industry and human health. − They are also analgesics, anti-inflammatory agents, allergy inhibitors, radical scavengers, anticancer agents, antibacterial agents, antidiabetic agents, and antioxidants. − Due to their biological uses, simplicity of synthesis, chelating properties, and stability, Schiff base compounds are an important and extensively studied class. − …”