Nadia A. El-Wakiel

Formation of novel mono- and multi-nuclear complexes of Mn(II), Co(II) and Cu(II) with bis azo-dianils containing the pyrimidine moiety: Thermal, magnetic and spectral studies

A novel series of Mn(II), Co(II) and Cu(II) complexes with some bisazo-dianils (compounds having two N=N and two HC=N groups) containing the pyrimidine moiety were prepared and characterized by elemental and thermal analyses, molar conductance and magnetic moment determination as well as IR, electronic absorption and ESR spectra. The data revealed different geometries around the metal ions, depending on both the ligand and metal ion.

UV/Vis, IR and 1H NMR spectroscopic studies of bisazo-dianil compounds based on 5-(2-carboxyphenyl azo)-salicylaldehyde and primary diamines

The electronic absorption and emission spectra of the titled biazo-dianils are studied in organic solvents of different polarity as well as in aqueous buffer solutions of varying pH. The important bands in the IR spectra as well as the main signals of the 1H NMR spectra are assigned. The observed UV/Vis absorption bands are assigned to the corresponding electronic transitions. The fluorescence quantum yield and pK(a)(-) values in the ground and excited states are determined.

Synthesis, spectral, antitumor, antioxidant and antimicrobial studies on Cu(II), Ni(II) and Co(II) complexes of 4-[(1H-Benzoimidazol-2-ylimino)-methyl]-benzene-1,3-diol

A new Schiff base of 2-aminobenzimidazole with 2,4-dihydroybezaldehyde (H₃L), and its Cu(II), Ni(II) and Co(II) complexes have been synthesized and characterized by elemental analyses, molar conductance, thermal analysis (TGA), inductive coupled plasma (ICP), magnetic moment measurements, IR, EI-mass, UV-Vis. and ESR spectral studies. On the basis of spectral studies and analytical data, it is evident that the Schiff base acts as dibasic tridentate ligand coordinating via deprotonated OH, NH and azomethine nitrogen atom. The results showed that Co(II) and Ni(II) complexes have tetrahedral structure while Cu(II) complexes has octahedral geometry. The kinetic and thermodynamic parameters of the thermal decomposition stages have been evaluated. The studied complexes were tested for their in vitro antimicrobial activities against some bacterial strains. The anticancer activity of the ligand and its metal complexes is evaluated against human liver Carcinoma (HEPG2) cell. These compounds exhibited a moderate and weak activity against the tested HEPG2 cell lines with IC₅₀ of 9.08, 18.2 and 19.7 μg/ml for ligand, Cu(II) and Ni(II) complexes, respectively. In vitro antioxidant activity of the newly synthesized compounds has also been evaluated.

Synthesis, spectral, thermal analyses, molecular modeling, and antimicrobial activities of Cu(II)-complexes with 1,3,4-oxadiazole Schiff-base derivatives

Seven Cu(II)-complexes with 2-amino-5-substituted aryl-1,3,4-oxadiazole Schiff bases are presented. The donors and possible geometries of the complexes were investigated by elemental and thermal (differential thermal analysis and thermogravimetric analysis) analyses, molar conductance, magnetic moments, IR, 1H-NMR, ESR, UV-Vis, and mass spectra. The ligands are bidentate, coordinating through the nitrogen of azomethine and the nearest nitrogen to it. The results are supported by 3-D molecular modeling of 2 using CS Chem 3-D Ultra Molecular Modeling and Analysis Program. The investigated complexes have been screened for in-vitro antibacterial (Escherichia coli and Staphylococcus aureus) and antifungal (Aspergillus flavus and Candida albicans) activities. The qualitative and quantitative antimicrobial activities prove that the complexes are very active against the tested microorganisms.

Chromone Schiff base complexes: synthesis, structural elucidation, molecular modeling, antitumor, antimicrobial, and DNA studies of Co(II), Ni(II), and Cu(II) complexes

A new Schiff base, namely 3-{(5-mercapto-1,3,4-thiadiazol-2-ylimino) methyl}-4H-chromen-4-one, and its complexes of divalent Co, Ni, and Cu ions have been synthesized. Elemental analyses, molar conductance, thermal analysis (TGA), inductive coupled plasma (ICP), magnetic moment measurements, and spectral techniques (X-ray powder diffraction, IR, EI-mass, 1H NMR, 13C NMR, UV–Vis, and ESR spectral studies) have been employed for structure elucidation of the target complexes. The spectral and analytical data revealed that the Schiff base acts as monobasic tetradentate ligand via deprotonated SH, oxygen atom of carbonyl group, and azomethine nitrogen atom for Ni2+ and Cu2+ complexes; bidentate via oxygen atom of carbonyl group and azomethine nitrogen atom for Co2+ complex. Molecular modeling calculations confirm the structural geometry of the complexes. The complexes were assayed for their in vitro antimicrobial activities against some bacterial strains. The anticancer activity of the target compounds is evaluated against human liver carcinoma (HEPG2) cell. These compounds exhibited weak activities against the tested HEPG2 cell lines. The interaction of the investigated materials with calf-thymus DNA was also studied.