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    Spectroscopic and electrochemical studies of transition metal complexes with N,N?-bis(2-aminothiophenol)-1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane and structure effects on extractability of ligand towards some divalent cations
    (Springer Wien, 2007) Temel, Hamdi; Alp, Hueseyin; Ilhan, Salih; Ziyadanogullari, Berrin; Yilmaz, Ismail
    La(III), Cu(II), Ni(II), and Zn(II) metal complexes with a novel quadridentate Schiff base derived from 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane and 2-aminothiophenol were synthesized and characterized by microanalytical data, elemental analysis, magnetic measurements, H-1 NMR, C-13 NMR, UV-Vis, IR, mass spectra, cyclic voltammetric and conductance measurements. The extractability of divalent cations was evaluated as a function of relationship between distribution ratio of the metal and pH or ligand concentration. The highest extraction percentage of Cu2+ and Ni2+ showed pH 7.0 and 6.4. It was concluded that the ligand can effectively be used in solvent extraction of copper(II) and nickel(II) from the aqueous phase to the organic phase.
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    Öğe
    Spectroscopic and extraction studies of new transition metal complexes with N,N'-bis(2-aminothiophenol)-1, 4-bis(2-carboxaldehydephenoxy)butane
    (Taylor & Francis Ltd, 2008) Temel, Hamdi; Alp, Hueseyin; Ilhan, Salih; Ziyadanogullari, Berrin
    Metal complexes of La(III), Cu(II) and Ni(II) with a thio Schiff base derived from 1,4-bis(2-carboxaldehydephenoxy)butane and 2-aminothiophenol have been synthesized in absolute ethanol and characterized by microanalytical data, magnetic measurements, H-1 NMR, C-13 NMR, UV-visible, IR-spectra, mass spectra and conductance measurements. The extractability of divalent cations was evaluated as a function of relationship between distribution ratios of the metal and pH or ligand concentration. The highest extraction percentage of Cu+2 and Ni+2 were at pH 7.0 and 6.4, respectively. The ligand can effectively be used in solvent extraction of copper(II) and nickel(II) from aqueous phase to organic phase.
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    Öğe
    Synthesis, electrochemistry and in situ spectroelectrochemistry of a new Co(III) thio Schiff-base complex with N,N?-bis(2-aminothiophenol)-1,4-bis(carboxylidene phenoxy)butane
    (Pergamon-Elsevier Science Ltd, 2008) Yilmaz, Ismail; Temel, Hamdi; Alp, Hueseyin
    A new cobalt Schiff-base complex, [Co(L)(OH)(H2O)] (where L = [N,N'-bis(2-aminothiophenol)-1,4-bis(carboxylidene phenoxy)butane), was synthesized and its electrochemical and spectroelectochemical properties were investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and thin-layer spectro-electrochemistry in solutions of dimethyl sulfoxide (DMSO) and dichloromethane (CH2O2). The [Co(L)(OH)(H2O)] complex displays two well-defined reversible reduction processes with the corresponding anodic waves. The half-wave potentials of the first and second reduction processes were displayed at E-1/2 = 0.08 V and E-1/2 = -1.21 V (scan rate: 0.100 Vs(-1)) in DMSO, and E-1/2 = -0.124 V and E-1/2 = -1.32 V (scan rate: 0.100 Vs(-1)) in CH2Cl2. The potentials of the reduction processes in DMSO are shifted toward negative potentials (0.220-0.112 V) compared to those in CH2O2. The electrochemical results are assigned to two one-electron reduction processes; [Co(III)L] + (-)e -> [Co(II)L](-) and [Co(II)L](-) + (-)e -> [Co(I)L](2-). The six-coordination of the complex remains unchanged during the reduction processes and the electron transfer processes were not followed by a chemical reaction upon scan reversal. It was also seen that [Co(L)(OH)(H2O)1 was reduced at a more positive potential than the corresponding salen analogs. The shift and reversibility are apparently related to the high degree of electron delocalization of the [Co(L)(OH)(H2O)] complex, having a N2O2S2 donor set and two additional benzene units. Additionally, in situ spectro-electrochemical measurements support Co(III)/Co(II) and Co(II)/Co(I) reversible reduction processes with the observation of the corresponding spectral changes with the applied potentials E-app = -0.40 and -1.60 V. Application of the spectroelectrochernical results allowed the determination of E-1/2 and n (the number of electrons) from the spectra of the fully oxidized and reduced species in one unified experiment as well. The results obtained by this method are in agreement with those by the CV and DPV methods. (C) 2007 Elsevier Ltd. All rights reserved.