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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. [ABSTRACT FROM AUTHOR]

A novel Schiff base ligand (H2L) was prepared through condensation of 2,6-diaminopyridine and o-benzoylbenzoic acid in a 1:2 ratio. This Schiff base ligand was characterized using elemental and spectroscopic analyses. A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal complexes of H2L were prepared and characterized using elemental analysis, spectroscopy (¹H NMR, mass, UV-visible, Fourier transform infrared, electron spin resonance), magnetic susceptibility, molar conductivity, X-ray powder diffraction and thermal analysis. The complexes are found to have trigonal bipyramidal geometry except Cr(III), Mn(II) and Fe(III) complexes which have octahedral geometry based on magnetic moment and solid reflectance measurements. The infrared spectral studies reveal that H2L behaves as a neutral bidentate ligand and coordinates to the metal ions via the two azomethine nitrogens. ¹H NMR spectra confirm the non-involvement of the carboxylic COOH proton in complex formation. The presence of water molecules in all reported complexes is supported by thermogravimetric studies. Kinetic and thermodynamic parameters were determined using Coats-Redfern and Horowitz-Metzger equations. The synthesized ligand and its complexes were screened for antimicrobial activities against two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), two Gram-negative bacteria (Escherichia coli and Neisseria gonorrhoeae) and one fungus (Candida albicans). Anticancer activities of the ligand and its metal complexes against human breast cancer cell line (MCF7) were investigated. [ABSTRACT FROM AUTHOR]

A novel Schiff base ligand, namely 2,2′‐((1E,1′E)‐(1,3‐phenylenebis(azanylylidene))bis(methanylylidene))diphenol (H2L), was synthesized by condensation of m‐phenylenediamine and 2‐hydroxybenzaldehyde (in 1:2 ratio). Series of complexes were obtained from the reaction of La(III), Er(III) and Yb(III) chlorides with H2L. The ligand and complexes were characterized using elemental analysis, infrared, 1H NMR, UV–visible and mass spectroscopies, magnetic susceptibility and conductivity measurements and thermal analysis. Infrared and 1H NMR spectra indicated the coordination of the azomethine nitrogens and deprotonated phenolic oxygen atoms in a tetradentate manner (ONNO). The thermal behaviour of the complexes was studied from ambient temperature to 1000°C. The complexes were found to have water molecules of hydration and coordinated water molecules. The complexes were found to possess high biological activities against various organisms compared to the free ligand (Gram‐positive bacteria Staphylococcus aureus and Bacillus subtilis, Gram‐negative bacteria Salmonella sp., Escherichia coli and Pseudomonas aeruginosa and fungi Aspergillus fumigatus and Candida albicans). The more effective and probable binding modes between H2L with different active sites of colon cancer (PDB code: 2hq6) and lung cancer (PDB code: 1x2j) receptors were investigated using molecular docking studies. [ABSTRACT FROM AUTHOR]