Nashwa M. El-Metwally

Spectral, magnetic, thermal and electrochemical studies on phthaloyl bis(thiosemicarbazide) complexes

The coordination behaviour of phthaloyl bis(thiosemicarbazide), H4PBT, towards VO2+, Co(II), Ni(II), Cu(II), Zn(II) and ions has been investigated. The elemental analyses, magnetic moments, spectra [UV-Vis, IR, ESR and MS] and thermal studies were used to characterize the isolated complexes. Cyclic voltammetry was used to study the electrochemical behaviour of the Cu(II) complex. The IR spectra showed that the ligand is deprotonated in the complexes and acts as a binegative SSNN donor. The f U–O (mdyn Å−1) and the length r U−O (Å) of the UO bond are calculated spectroscopically from the IR data. The loss of thiol hydrogen during the formation of complexes was confirmed from the pH-metric titrations of the ligand and its metal(II) complexes. The protonation constants of the ligand (pK1 = 9.45 and pK2 = 7.25) as well as the stability constants of its complexes were calculated. The intensity and position of the V=O band in the IR spectra reflect the geometry of the formed complex. Also, its colour (dark green) is consistent with the suggested stereochemistry. The binuclear VO2+ complex was isolated and confirmed by ESR spectra. The TG analyses for the VO2+, Co(II), Ni(II) and Zn(II) complexes suggest different decomposition steps. The Coats–Redfern and Horowitz–Metzger equations have been used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. The redox properties, nature of the electroactive species and the stability of the Cu(II) complex toward oxidation were examined. The electrochemical data are discussed in terms of the kinetic parameters and the reaction mechanism.

Chelating activity of bis(diacetylmonoxime)thiocarbohydrazone towards VO2+, Co(II), Ni(II), Cu(II) and Pt(IV) ions

A new chelating agent, bis(diacetylmonoxime)thiocarbohydrazone (H3DMT), has been synthesized from reaction between diacetylmonoxime and thiocarbohydrazide. The prepared ligand, characterized by elemental analysis, IR and 1H NMR spectra, is a strong chelating agent and indicator. Its coordinating properties have been studied toward VO2+, Co(II), Ni(II), Cu(II) and Pt(IV) ions. The data revealed the formation of mononuclear complexes with Co(II) and Pt(IV) and binuclear complexes with the rest. In all complexes, the ligand binds in its deprotonated form through the oxime and hydrazone nitrogens as well as the thiol or thione sulfur forming five- and six-membered rings. All complexes exhibit an octahedral structure except for the Cu(II) which has a square-pyramidal geometry based on the spectral and magnetic studies. The ESR spectra of the Cu(II) and VO2+ complexes are in good agreement with the structural results. The color change from acidic (yellow) to basic (reddish brown) media gives the ligand the ability to become as an analytical indicator for weak acid–weak base titrations.

Spectroscopic, magnetic and thermal studies on complexes of Cu(II) and VO2+ with diacetylmonoxime derivatives: new method for extraction of Cu(II)

The coordination behavior of Cu(II) and VO2+ towards some oximes has been investigated. The isolated complexes were characterized by elemental analysis, molar conductance, magnetic moment, spectra (electronic, IR, ESR and mass) and thermal measurements. The IR spectra showed most ligands are deprotonated during complex formation acting as mononegative bi- or tridentate, binegative tetradentate and neutral tridentate. The magnetic moments and electronic spectra showed octahedral, square pyramidal and square-planar structures for the Cu(II) and VO2+ complexes. The ESR spectra of the complexes are quite similar and exhibit axial symmetric g-tensor parameters with g ∥ > g ⊥ > 2.0023 and confirmed the structures. The TG curves showed decomposition steps and indicate stability of the complexes. The ligands can remove Cu(II) ions from water by flotation technology using oleic acid surfactant with high efficiency.

Spectral and Biological Investigation for Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) Complexes With Optically Active Compound

A series of complexes was prepared using optically active compound as ephedrine. Previously Cu(II)-ephedrine complex was prepared and completely different from that prepared in the study concerning the structural and molecular formula. The previous study on ephedrine was concerned on the optical activity for the chiral organic ligand. Here the author focuses on the coordination behavior of the ligand toward the metal ions. The mode of coordination was discussed based on IR and Raman spectra and suggested a neutral bidentate. The electronic spectra and magnetic measurements are coinciding for proposal geometry. The EPR spectral parameters confirm the square-pyramidal geometry of Cu(II) complex; the mass and 1HNMR spectra of Cu(II) and Zn(II) complexes, respectively, support the molecular formula. The thermogravimetric analysis and the kinetic parameters were carried out for most complexes. The effect on DNA degradation was discussed on all prepared complexes in comparing with the free organic compound.