Ali Reza Ghaderi

Tarbiat Modares University, Teheran, Tehrān, Iran

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Publications (2)3.92 Total impact

  • Ali Reza Ghaderi, Hassan Sabzyan, Nasser L Hadipour
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    ABSTRACT: Nuclear quadrupole coupling constants (NQCC), chi, and asymmetry parameters, eta, of 2D, 14N and 17O nuclei have been calculated for aliphatic amino acids and their dimers using MP2/6-311++G** method to shed some light on the differences between the structural parameters in the aliphatic amino acids and their dimers. For this purpose, electric field gradient (EFG) at the sites of quadrupolar nuclei have been calculated and evaluated for each compound. A correlation is observed between the calculated NQCC parameters and the conformational structures of the compounds, showing that extraction of structural data from the NQR spectra might be promising. Our results showed that 17O NQCC of terminal carboxylic acid and 14N NQCC of the terminal amino groups are, respectively, the least and the most sensitive parameters to the variation of the size of the residue. It is found also that conformation of R (i.e. values of the dihedral angles) plays a very effective role in the determination of the values of the calculated NQCC parameters. Sensitivity of the NQR parameters to the changes in the conformational structure is significantly greater (nearly 20-fold) than that to the changes in the other structural parameters such as bond lengths.
    Biophysical Chemistry 04/2006; 120(1):62-70. · 2.32 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The molecular recognition of l-amino acids such as asparagine, glutamine, lysine and arginine with some crownpyryliums, CP's, and a crownpyridinium compound, as receptors, were examined in methanol. 1H NMR spectroscopy was used to examine the structural stability of the receptors in the presence of the amino acids. The fluorimetric titration of the receptors by specified amino acids, other than arginine, was followed within a few minutes and the stoichiometry and stability of the resulting amino acid complexes were evaluated. The data analysis clearly demonstrated the critical role of the terminal amino group to carboxylic acid distance of amino acids for their proper fixation on the receptor molecules. Ion pairing for the two oppositely charged carboxylate anion and pyrylium (or pyridinium) cation, as well as the hydrogen bonding between crown ethers' oxygens and ammonium hydrogens are expected as the main interaction sources in the host–guest complexations.
    Journal of Molecular Structure 10/2005; · 1.60 Impact Factor

Publication Stats

9 Citations
3.92 Total Impact Points

Institutions

  • 2006
    • Tarbiat Modares University
      • Department of Chemistry
      Teheran, Tehrān, Iran
  • 2005
    • Imam Hossein University
      Teheran, Tehrān, Iran