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1

Voltammetric Study of Interaction of Copper with Some Methyl-Substituted Ethylenediimine Compounds Using Nonlinear Least-Squares-Excel-Solver

Fotouhi L., Bahmanpour T., Ghasemi J., Dehghanpour S., Heravi M.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 3

483-489

EN

The complex formation of Cu2+ with some recently synthesized methyl-substituted ethylenediimines in binary dimethylformamide-ethanol mixtures was studied by differential pulse voltammetry. The stoichiometry and the stability of the complexes were determined by monitoring the increasing complex peak current against the ligand concentration using nonlinear least squares-Excel solver. In all studied cases, it was found that the stability of the resulting 1:1 complex decreases by increasing the amount of ethanol in the binary mixtures. The observed stability order is discussed in terms of the solvent binary mixtures and the nature of the substituted ethylenediimine structure.

2

Electrochemical Studies of N,N'-Bis-(beta-phenylcinnamaldehyde) Phenylenediimine in Dimethylformamide

Fotouhi L., Nazari S., Dehghanpour S.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 8

1327-1338

EN

The electrochemical reduction mechanism of novel ligand N,N'-bis(_-phenylcinnamaldehyde) phenylenediimine has been investigated in the potential range -1.1 V to -2.7Von glassy carbon (GC) and mercury (Hg) electrodes. Reduction of >C=N bonds was studied in dimethylformamide using direct current (DC) voltammetry, differential pulse (DP) voltammetry, cyclic voltammetry (CV), chronoamperometry, chronocoulometry and coulometry. The studied process consists of two irreversible 2-electron transfers attributable to the reduction of azomethine bonds. The diffusion and transfer coefficients are reported. Adsorption characteristics of the molecule on a mercury electrode were studied and the maximum surface excess was found to be about 1.8x10-10 mol cm-2.

3

Voltametric Behavior of the Nitro Radical Anion Generated Electrochemically from Furazolidone at Glassy Carbon Electrode

Fotouhi L., Kiapasha L.

Polish Journal of Chemistry

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2004

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Vol.78 /nr 11-12

2175-2184

EN

The electrochemical behavior of the nitro radical anion resulted from the reduction of furazolidone has been studied in mixed aqueous-dimethylformamide (DMF) solvent at glassy carbon electrode (GCE) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Furazolidone is reduced in two cathodic steps in the low concentration of DMF and acidic media, giving hydroxylamine and amine derivatives via reduction by four and two electrons, respectively. The addition of DMF to the basic buffer solution enables the presence of two different reduction processes to be established. The first cathodic peak is related to a 1e-reversible reduction process corresponding to the formation of nitro anion radical (RNO2 Ĺ ) and the more negative peak is due to the formation of hydroxylamine via a 3e-irreversible reduction process. The cyclic voltammetry technique has been employed to the study of RNO2/RNO2 Ĺ couple. The reversibility of radical anion is investigated by the ratio of anodic to cathodic current, Ia1/Ic1, by increasing DMF content and pH. The influence of scan rate on the Ia1/Ic1 ratio shows an ECi mechanism, in which this subsequent chemical reaction corresponds to protonation reaction ofRNO2 Ĺ that is initiated electrochemically. The effect of cationic and anionic surfactants has been reported on the electrochemical behavior of furazolidone.

4

Electrochemical Behaviour of Chloride and Bromide Complexes of Palladium(II) with 4-Amino-6-methyl-3-thio-3,4-dihydro-1,2,4-triazin-5(2H)-one in Dimethylformamide at Glassy Carbon Electrode

Fotouhi L., Ghassemzadeh M., Heravi M. M.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 7

895-902

EN

The electrochemical behaviour of palladium(II) complexes of PdCl2L(I) and PdBr2L(II) (L = 4-amino-6-methyl-3-thio-3,4-dihydro-1,2,4-triazin-5(2H)-one) has been investigated in dimethylformamide at glassy carbon electrode. Under cyclic voltammetric conditions, complex PdCl2L is found to undergo a one-electron oxidation at 1.27 V with a prewave, which is similar to oxidation of ligand L. The oxidation of ligand shows an oxidation wave at 1.25 V with EC mechanism. In the chemical reaction following the one electron irreversible oxidation of ligand, the electrochemical-generated cation radical forms a dimer, which is reduced at reverse scan at -0.66 V to reproduce the monomer. Thus, the nature of oxidation of both complexes I and II suggests a ligand-centered oxidation, because their oxidation behaviour is similar to oxidation of ligand L. However, the reduction of both complexes I and II shows a reduction peak at -1.31 V and -1.33 V respectively, which is related to reduction of metal center of complexes, Pd (II) to Pd (I).

5

Electrochemical Behavior of some Thioheterocyclic Compounds in Aqueous-Methanolic Media at Mercury Electrodes

Fotouhi L., Sadeghi R.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 10

1313-1321

EN

This paper presents the electrochemical behavior of 4-amino-3-thio-1,2,4-triazole (I), 4-amino-3-thio-5-methyl-1,2,4-triazole (II) and 4-amino-6-methyl-3-thio-1,2,4-triazin- 5-one (III) at mercury electrodes. The study is performed in aqueous-methanolic solutions by differential pulse polarography (DPP), cyclic voltammetry (CV), chronoamperometry, coulometry and spectrophotometry. All three compounds exhibited one reversible oxidation peak, accompanied by a prepeak, due to the adsorption of these compounds on the electrode. The main peak in each case was found to be diffusion controlled. Their polarographic responses were similar to those of common thiol compounds and involved a one electron oxidation of mercury followed by a disproportionation step to form the mercury(II) salt and Hg, (EC mechanism). The protonation constants (pK), diffusion constants, the rate constants of coupled chemical reaction and transfer coefficients were also obtained.