Gholamhossein Shafiee

Shahid Beheshti University, Teheran, Tehrān, Iran

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Publications (2)0.69 Total impact

  • F. Gharib · H. Aghaei · A. Shamel · A. Taghvamanesh · G. Shafiee ·
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    ABSTRACT: The dependence of L-glutamine protonation and its complexation with dioxovanadium(V) on ionic strength (I) is reported in sodium perchlorate solution as a background salt. The measurements have been performed at 25 0.1C and various ionic strengths in the range 0.1 to 1.0 mol/l, using a combination of potentiometric and spectrophotometric techniques. The overall analysis of the present and the previous data dealing with the determination of stability constants at different ionic strengths allowed us to obtain a general equation, by which a formation constant determined at a fixed ionic strength can be calculated, with a good approximation, at another ionic strength, if 0.1 I 1.0 mol/l (NaClO4).
    Russian Journal of Coordination Chemistry 01/2003; 29(6):408-413. DOI:10.1023/A:1024034227434 · 0.48 Impact Factor
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    ABSTRACT: The stability consts. of the complexes of thallium(I) ion with some sulfur-contg. amino acids (L-cysteine, N-acetyl-Lcysteine, and L-methionine) were detd. in aq. soln. in the range 1.4 £ pH £ 10.5 at 0.1 mol dm-3 ionic media and 25 °C, using a combination of potentiometric and spectrophotometric techniques. Sodium perchlorate soln. was used to maintain the ionic strength. The compns. of the formed complexes were detd. and it was shown that thallium(I) forms two mononuclear 1:1 species with cysteine and methionine of the type TlHL and TlL- and only one mononuclear 1:1 complex with N-acetylcysteine of the type TIL-. The logarithms of the cumulative stability consts., bxyz, of the complexes, [(metal ion)x(H)y(ligand)z], are logb111 and logb101 = 11.03, 11.41 (for cysteine), 0.37, 2.19 (for methionine), resp., and logb101 = 2.93 for N-acetylcysteine.
    Main group metal chemistry 01/2003; 26(1):39-47. DOI:10.1515/MGMC.2003.26.1.39 · 0.21 Impact Factor