Synthesis, structural studies and antimicrobial evaluation of nickel (II) complexes of NNS tridentate thiosemicarbazone based ligands

Successful preparation of Schiff base 4‐(4‐aminophenoxy)‐N‐(1‐(pyridin‐2‐yl)ethylidene)aniline derived from refluxing of 4,4‐oxydianniline with 2‐acetylpyridine within 2 h in 1:1 molar ratio was performed. Different transition metal complexes were synthesized by reacting metal chlorides with the formed ligand in 1:1 molar ratio. Structural features of the complexes were obtained from different tools such as infrared (IR), 1H‐nuclear magnetic resonance (1H‐NMR), ultraviolet–visible (UV‐vis), molar conductivity, thermogravimetric (TG)/differential thermogravimetric (DTG), microanalysis, and mass spectrometry. All complexes had an octahedral structure and Schiff base acted as a neutral bidentate ligand that linked to metal centers via N‐azomethine and N‐pyridine atoms. Cr(III), Fe(III), and Ni(II) complexes were electrolytes while other complexes were nonelectrolytes. The molecular structure of Schiff base was optimized theoretically and its HOMO and LUMO energies were dictated by B3LYP/DFT calculations. The in vitro antibacterial activity versus some selected bacteria species showed that all prepared compounds were biologically active except Fe(III) complex against certain species and Co(II) complex had the highest biological activity values. Molecular docking was used to determine effective binding modes between ligand and its [Co(L)(H2O)2Cl2]·4H2O complex with active sites of 4WJ3, 4ME7, 4K3V, and 3T88 receptors. The strongest binding of Co(II) complex was with the 4ME7 receptor with lowest binding energy value −25.4 kcal mol−1. Schiff base as corrosion inhibitors for mild steel in 1.0‐M HCl had been investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PP), and electrochemical frequency modulation (EFM). The results showed that the inhibitor acts as a mixed‐type inhibitor. The inhibition efficiency increases with increasing inhibitor concentration to its maximum of 97.5% at 1 × 10−3 M solution. The adsorption model obeys the Langmuir isotherm, and Gibbs free energy was around −40 kJ/mol, indicating that it is spontaneously and chemically adsorbed on the surface. SEM/EDX results proved the sticking of a barrier film on the mild steel sample.

Section: Resultsmentioning

confidence: 99%

Antibacterial and anticorrosion behavior of bioactive complexes of selected transition metal ions with new 2‐acetylpyridine Schiff base

Deghadi

Elsharkawy

Ashmawy

et al. 2022

“…[ 98 ] In the same way we found that compound 4 has better activity (14.3 and 13.3 mm) than the Ni(II) compound [NiCl(L 1 )] (14.0 and 13.0) against S. aureus and E. coli , respectively. [ 99 ]…”

Section: Resultsmentioning

confidence: 99%

Synthesis, spectroscopic, electrochemical characterization, density functional theory (DFT), time dependent density functional theory (TD‐DFT), and antibacterial studies of some Co(II), Ni(II), and Cu(II) chelates of (E)‐4‐(1,5‐dimethyl‐3‐oxo‐2‐phenyl‐2,3‐dihydro‐1H‐pyrazol‐4‐yl)‐1‐(3‐hydroxynaphthalen‐2‐yl)methylene) thiosemicarbazide Schiff base ligand

El‐Sawaf

Abdel‐Monem

Azzam

2020

In this study, mononuclear Co(II), Ni(II), and Cu(II) chelates of the potentially tridentate O, N, S donor ligand (E)-4-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-1-(3-hydroxynaphthalen-2-yl)methylene) thiosemicarbazide (H 2 L) were synthesized and characterized by elemental analyses, conductivity measurements, Fourier transform infrared spectroscopy, UV-visible spectroscopy, magnetic susceptibility, electron spin resonance (ESR) spectral analysis, thermal thermogravimetric analyses, cyclic voltammetry, and theoretical density functional theory (DFT) and time dependent density functional theory (TD-DFT) studies. The potential donors O (phenolic) and N (azomethine) are found in a syn configuration due to a strong intramolecular hydrogen bond [O-H …. N(1)] as shown in the 1 H NMR spectrum of the free ligand. In addition, analytical results revealed the formation of the metal chelates in a ligand-to-metal molar ratio of 1:1. The organic ligand (H 2 L) coordinated to the metal center through azomethine nitrogen, phenolate oxygen, and thione/thiolate sulfur groups with the formation of a five-and six-membered rings. The magnetic and spectral results supported the formation of tetrahedral geometry around the Co(II) and Ni(II) centers, while Cu(II) centers were assumed to have a square planar geometry. The time dependent density functional theory (TD-DFT) calculation outputs were used to expect and explain the experimental bathochromic and hypsochromic shifts resulting from the ligand chelation. The antibacterial activity of the compounds under study was evaluated in vitro against Staphylococcus aureus and Escherichia coli demonstrating Gram-positive and Gram-negative bacteria, respectively. It was found that among synthesized compounds, Cu(II) chelate 5 showed the most inhibitory activity against both Gram-positive and Gram-negative

“…The ligands have shown usefulness in coordination chemistry with a chelation mode of pyridine-2-carboxaldehyde TSC ligands via the azomethine (N), pyridinyl (N), and thiolate (S) atoms in a monobasic character that has been shown by single crystal XRD studies of respective metal complexes. [7,[27][28][29][30][31] These tridentate ligands are stable at room temperature and exhibit thione-thiol tautomerism in the solid form, but the thiol conformation is predominant in the ligand solution. [28][29][30][31] The reaction of Pb (II) and Hg (II) with the TSCs took place in aqueous ethanol under refluxing conditions and the solids formed were washed extensively with boiling water to remove unreacted metal precursor.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…[7,[27][28][29][30][31] These tridentate ligands are stable at room temperature and exhibit thione-thiol tautomerism in the solid form, but the thiol conformation is predominant in the ligand solution. [28][29][30][31] The reaction of Pb (II) and Hg (II) with the TSCs took place in aqueous ethanol under refluxing conditions and the solids formed were washed extensively with boiling water to remove unreacted metal precursor. The yellow complexes were obtained in moderate yields (51%-77%) and exhibited very poor solubility at room temperature in several organic solvents, for example, methanol, ethanol, acetone, and methylene chloride.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…[26] Recently, we prepared a number of pyridine-2-carboxaldehyde thiosemicarbazone ligands and investigated the structural and antimicrobial activities of their complexes with Mn (II), Ni (II), Cu (II), Zn (II), and Cd (II) ions. [7,[27][28][29][30][31] In this work, we have investigated the reaction of two of the ligands (Figure 1), HL 1 {4-[4-nitrophenyl]-1-[(pyridin-2-yl)methylene]thiosemicarbazide} and HL 2 {4-[2-chloro]-1-[(pyridin-2-yl)methylene]thiosemicar-bazide} with the heavy metal ions Pb (II) and Hg (II). We have further investigated the ability of the resulting metal complexes to inhibit growth of the human pathogen C. sphaerospermum through their effect on the cellular soluble protein (SP), dry mass (DM), total antioxidant (TA), and sugar consumption.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Pb (II) and Hg (II) thiosemicarbazones for inhibiting the broad‐spectrum pathogen Cladosporium sphaerospermum ASU18 (MK387875) and altering its antioxidant system

Ibrahim

Mahmoud

Cordes

et al. 2022

Self Cite

Pb (II) and Hg (II) ions were reacted in aqueous solution with two tridentate thiosemicarbazones, resulting in four complexes {[Pb(L1)2] 1, [Pb(L2)2] 2, [Hg(L1)2] 3, and [Hg(L2)2] 4; HL1 = 4‐(4‐nitrophenyl)‐1‐[(pyridin‐2‐yl)methylene]thiosemicarbazide and HL2 = 4‐(2‐chlorophenyl)‐1‐[(pyridin‐2‐yl)methylene]thiosemicarbazide}. The solid‐state structures of complexes 2 and 3 were determined by X‐ray crystallography, which also confirmed the monobasic tridentate NNS nature of the ligands, and the octahedral coordination geometry around the metal centers. Complexes 1–4 exhibited high antifungal activity against the pathogen Cladosporium sphaerospermum; all four complexes give rise to a reduction in the fungal dry mass and sugar consumption. Complexes 2 and 4 that inhibited C. sphaerospermum growth at the concentration of 1.8 mM are more efficient inhibitors than the free ligand and metal ions. Further, the complexes gave varied values of the fungal total antioxidants (TA), superoxide dismutase (SOD), and catalase (CAT) activities dependent on their concentrations.