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Computational Electrochemistry of the Two-Step Reduction Potentials of Some Quinones Using DFT Response Combined with CPCM Continuum Solvation Model in Acetonitrile

Alizadeh K., Shamsipur M., Biglari Z., Namazian M.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 10

1771-1782

EN

DFT calculations have been performed using B3LYP with 6-31G* and 6-31G** basis sets in combination with CPCM (COSMO) dielectric continuum model to investigate two stepwise reduction potentials for eight different quinone derivatives in acetonitrile solution. The electrode potentials of quinone molecules were calculated relative to a reference molecule and compared with the experimental findings. The root mean square errors (r.m.s.) of the calculations based on B3LYP/6-31G* and B3LYP/6-31G** methods found to be 0.14 and 0.12 V, respectively. Analysis of correlation between the experimental electrode reduction potentials and the theoretically calculated values revealed that notable relations existed between the two stepwise reduction electrode potentials and the eigenvalues of LUMOs of the quinone derivatives.

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Density Functional Theory Calculations of Oxidation Potentials of Some Aromatic Hydrocarbons Derivatives in Acetonitrile

Alizadeh K., Seyyed S., Shamsipur M.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 7

1449-1449

EN

Density functional theory method at the level of B3LYP in combination with the polarizable continuum model have been used to compute one-electron oxidation potentials for fifteen different aromatic hydrocarbons derivatives in acetonitrile solution. A linear relation ship was observed between the the o retically predicted redox values and experimentally determined anodic peak potentials of the aromatic hydrocarbons derivatives. A good correlation is also found between experimental anodic peak oxidation potentials and a simple computed property, namely the energy of the high est occupied molecular orbital for neutral or radical cation of the aromatic hydrocarbons in acetonitrile (R2 = 0.95).

3

Application of Chemometrics and Quantum Chemical Calculations to the Study of Complexation Equilibria Between 1,8-Bis(o-aminophenoxy)-3,6-dioxaoctane and Some Transition and Heavy Metal Ions in Acetonitrile Solution

Shamsipur M., Ghavami R., Hemmateenejad B., Sharghi H., Alizadeh K., Niknam K.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 8

1621-1621

EN

Evolutionary factor analysis (EFA) and rank annihilation factor analysis (RAFA) were applied to resolve the two-way equilibrium spectrophotometric data for the determination of stability constants of the complexes of 1,8-bis(o-aminophenoxy)-3,6-dioxaoctane (BOAPD) with Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+ and Hg2+ ions. The number of component species was determined by factor analysis of the absorbance data and then a hard model between the analytical concentrations of the ligand and metal ions, the equilibrium concentrations of all species present and the corresponding equilibrium constants was written. By knowing the equilibrium constants, the equilibrium concentrations of the species will be calculated at each metal to ligand mole ratio. The values of equilibrium constants were varied iteratively and, at each iteration, the ligand’s in formation (i.e., the equilibrium concentration and spectral in formation) were annihilated from the original data matrix until the rank of the original data matrix was reduced by one. The results revealed that ligand forms ML complexes with Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ and a ML2 adduct with Hg2+ ion. The equilibrium constants, the concentration and spectrum profiles of each complexed species were then calculated. The residual standard deviation (RSD) of the residual matrix after bilinearization of the back ground matrix is regarded as the evaluation function.

4

Lithium-7 NMR and ab initio Calculation Studies of Complexation of Li+ Ion with 12-Crown-4, Benzo-12-crown-4, 15-Crown-5, Benzo-15-crown-5, and Dibenzo-15-crown-5 in Binary Nitromethane-Acetonitrile Mixtures

Shamsipur M., Alizadeh N., Rofouei M. K., Alizadeh K.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 10

1743-1743

EN

Complexes of 12-crown-4 (12C4), benzo-12-crown-4 (B12C4), 15-crown-5 (15C5), benzo-15-crown-5 (B15C5) and dibenzo-15-crown-5 (DB15C5) with Li+ ion were investigated by lithium-7 NMR in a number of nitromethane (NM)-acetonitrile (AN) binary mixtures. In all cases, the exchange between the free and complexed lithium ionwas fast on the NMR time scale and a single population average resonance was observed. Both 1:1 and 2:1 (sandwich) complexeswere observed between lithium ion and 12C4 and B12C4 in pure nitromethane solution. Stepwise formation constants of the 1:1 and 1:2 (metal/ligand) complexes were evaluated from computer fitting of the NMR mole ratio data to equations which relate the observed metal ion chemical shifts to formation constants. There is an inverse linear relationship between the logarithms of the stability constants and the mole fraction of acetonitrile in the solvent mixtures. The stability of the complexes varies inversely with the Gutmann donor number of the solvent. The stability order of the complexes was found to be 15C5.Li+> B15C5.Li+> DB15C5.Li+> 12C4.Li+ > B12C4.Li+. The optimized structures of the free ligands and their 1:1 and 2:1 complexes with Li+ ionwere predicted by ab initio theoretical calculations using theGaussian 98 software, and the results are discussed.

5

Differential Pulse Polarographic Study of Mercury Complexes with Some Substituted Pyrimidines in Binary Acetonitrile-Dimethylformamide Mixtures

Maddah B., Alizadeh K., Shamsipur M., Moghimi A., Ganjali M.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 5

737-744

EN

The complex formation of Hg2+ ion with five synthesized substituted pyrimidines in binary acetonitrile-dimethylformamide (AN-DMF) mixtures was studied by differential pulse polarography at 25 graduate C. The stoichiometry and stability of the complexeswere determined by monitoring the shift in the Hg2+ differential pulse peak potential against the pyrimidines concentration. In all cases studied, itwas found that the stability of the resulting 1:1 complex decreases drastically by increasing the amount of dimethylformamide in the binary mixtures. The observed stability order in a given solvent mixture is discussed in terms of the solvating ability of the solvent, donor site number, and steric hindrance on the pyrimidines.