Spectroscopic studies and biological evaluation of some transition metal complexes of azo Schiff-base ligand derived from (1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one) and 5-((4-chlorophenyl)diazenyl)-2-hydroxybenzaldehyde

Complexes of VO2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Ru3+ and UO22+ with (3‐(hydroxyimino)butan‐2‐ylidene)isonicotinohydrazide were synthesized and characterized using physical and spectral methods. Analytical data revealed that the complexes formed in 1:1 or 1:2 metal–ligand ratios. Spectral studies showed that the ligand bonded to the metal ion in neutral tridentate, monobasic tridentate or monobasic bidentate fashion through azomethine nitrogen atom, protonated/deprotonated imine oxime group and/or ketonic/enolic carbonyl group. From the electronic spectral data together with magnetic susceptibility values a square planar, tetrahedral or distorted octahedral structure can be proposed for all complexes. Electron spin resonance spectra for Cu2+ complexes (2–4) revealed axial symmetry with g|| > g⊥ > ge, indicating distorted octahedral or square planar structures and the unpaired electron exists in a dx2−y2 orbital with marked covalent bond feature. The prepared complexes showed good to excellent biological activity, and the most active complexes against Aspergillus niger were 4 and 9 with zone of inhibition of 25 and 23 mm, respectively. Complexes 10 and 11 showed interesting activity against Escherichia coli with zone of inhibition of 44 and 32 mm, respectively.

Section: Introductionmentioning

confidence: 99%

Transition metal complexes of a hydrazone–oxime ligand containing the isonicotinoyl moiety: Synthesis, characterization and microbicide activities

Shakdofa

El‐Saied

Rasras

et al. 2018

“…This has led to a variety of applications related to their biological activity. The electron‐donor properties of the Schiff base ligands, functional groups in their structures and their position in the coordination sphere of their chelates were the main factors affecting their reactivates in various studies . It is known that copper complexes show anti‐nuclear activity and also they have an effect against rheumatoid arthritis .…”

Section: Introductionmentioning

confidence: 99%

Coordination behaviour and biological activity studies involving theoretical docking of bis‐Schiff base ligand and some of its transition metal complexes

Zayed

Hindy

et al. 2018

The Schiff base ligand 1,2-bis(2-vinylphenoxy)ethane-4,6-diaminopyrimidine-2-thiol derived from the condensation of 4,6-diaminopyrimidine-2-thiol with bisaldehyde was synthesized and characterized. Coordination compounds of this Schiff base with transition metal cations Cd(II), Zn(II), Ni(II), Co(II), Mn(II), Cu(II) and Fe(III) were synthesized and characterized. Microanalytical data, magnetic moments, mass, 1 H NMR and infrared spectra, molar conductance measurements and thermal analyses were used to confirm the structures of the obtained Schiff base ligand and its chelates. According to the data obtained, the 1:1 general stoichiometric formulae of chelates are given by [M(HL)(H 2 O) 2 ]Cl 2 (M = Cd(II), Zn(II), Ni(II), Co(II), Mn(II), Cu(II)) and [Fe(HL)(H 2 O) 2 ]Cl 3 . The diffuse reflectance spectra and magnetic moment measurements suggest an octahedral geometry for the complexes. The bis-Schiff base ligand and metal ions are coordinated in a tetradentate manner via OO and NN donor sites as confirmed by infrared spectra. These complexes were then subjected to antibacterial studies using Gram-positive (Streptococcus pyogenes and Bacillus subtilis) and Gram-negative (Proteus vulgaris and Escherichia coli) organisms. The ligand and metal complexes exhibited pronounced antimicrobial activity against both types of bacteria. A docking study was conducted to evaluate the nature of the binding of the ligand and the most biologically active complexes to protein active sites of these bacteria. KEYWORDS antimicrobial activity and molecular docking studies, bis-Schiff base ligand, elemental and spectroscopic studies, thermal analyses, transition metal complexes

“…New Schiff base ligands display distinctive characteristics and effectiveness, and their preparation is an important step in the development of metal complexes. Therefore, various studies have been conducted on the properties of electron acceptor and donor ligands, function groups of ligands and coordination sphere of ligands in complexes . Some groups attracted interest years ago and are still studied, especially the azomethine group, frequently exhibiting unusual structural properties in complexes made with a diverse number of transition metals .…”

Section: Introductionmentioning

confidence: 99%

Molecular structure, molecular docking, thermal, spectroscopic and biological activity studies of bis‐Schiff base ligand and its metal complexes

Zayed

Hindy

2017

Mn(II) ions were synthesized from the ligand [4,4′-((((ethane-1,2-diylbis(oxy)) bis(2,1-phenylene))bis(methanylylidene))bis(azanylylidene))diphenol]ethane (H 2 L) derived from the condensation of bisaldehyde and 4-aminophenol. Microanalysis, magnetic susceptibility, infrared, 1 H NMR and mass spectroscopies, molar conductance, X ray powder diffraction and thermal analysis were used to confirm the structure of the synthesized chelates. According to the data obtained, the composition of the 1:1 metal ion-bis-Schiff base ligand was foundand Mn(II), n = 2; Fe(III), n = 3). Magnetic susceptibility measurements and reflectance spectra suggested an octahedral geometry for the complexes. Central metals ions and bis-Schiff base coordinated together via O2 and N2 donor sites which as evident from infrared spectra. The Gaussian09 program was applied to optimize the structural formula for the investigated Schiff base ligand. The energy gaps and other important theoretical parameters were calculated applying the DFT/B3LYP method. Molecular docking using AutoDock tools was utilized to explain the experimental behaviour of the Schiff base ligand towards proteins of Bacillus subtilis (5 h67), Escherichia coli (3 t88), Proteus vulgaris (5i39) and Staphylococcus aureus (3ty7) microorganisms through theoretical calculations. The docked protein receptors were investigated and the energies of hydrogen bonding were calculated. These complexes were then subjected to in vitro antibacterial studies against several organisms, both Gram negative (P. vulgaris and E. coli) and Gram positive (S. pyogones and B. subtilis). The ligand and metal complexes exhibited good microbial activity against the Gram-positive andGram-negative bacteria.KEYWORDS bioinorganic chemistry, bis-Schiff base ligand, in vitro biological activity, IR spectroscopy, metal complexes, thermal analysis