Metal ion-binding properties of L-glutamic acid and L-aspartic acid, a comparative investigation

A comparative research has been developed for acidity and stability constants of M(Glu)1, M(Asp)2 and M(Ttr)3 complexes, which have been determined by potentiometric pH titration. Depending on metal ion-binding properties, vital differences in building complex were observed. The present study indicates that in M(Ttr) com-plexes, metal ions are arranged to the carboxyl groups, but in M(Glu) and M(Asp), some metal ions are able to build chelate over amine groups. The results mentioned-above demonstrate that for some M(Glu) and M(Asp) complexes, the stability constants are also largely determined by the affinity of metal ions for amine group. This leads to a kind of selectivity of metal ions, and transfers them through building complexes accompanied with glutamate and aspartate. For heavy metal ions, this building complex helps the absorption and filtration of the blood plasma, and consequently, the excursion of heavy metal ions takes place. This is an important method in micro-dialysis. In this study the different as-pects of stabilization of metal ion complexes regarding to Irving-Williams sequence have been investigated.

A Comparative Investigation of Lead Sulfate and Lead Oxide Sulfate Study of Morphology and Thermal Decomposition

The compound lead oxide sulfate PbSO4.PbO was prepared in our laboratory. The Thermal behavior of PbSO4 was studied using techniques of Thermogravimetry under air atmosphere from 25 to 1200°C. The identity of both compounds was confirmed by XRD technique. Results obtained using both techniques support same decomposition stages for this compound. The electron microscopic investigations are made by SEM and TEM. The compound is characterized by XRD and the purity was determined by analytical Methods. Also a series of thermogravimetric analysis is made and the ideal condition is determined to convert this compound to pure lead oxide.

Equilibria and Stability in Glycine, Tartrate and Tryptophan Complexes, Investigation on Interactions in Cu(II) Binary and Ternary Systems in Aqueous Solution

The acidity and stability constants of M(Gly)1, M(Ttr)1, and M(Trp)1 M: Cu2+, Cu(Bpy2)2+, and Cu(Phen3)2+ complexes, were determined by potentiometric pH titration. It is shown that the stability of the binary Cu(L), (L: Gly, Ttr, and Trp) complex is determined by the basicity of the carboxylate group on one side and amino group on the other side. It is demonstrated that the equilibrium, Cu(Ha4)2+ + Cu(L) Cu(Har)(L) + Cu2+, is displacement due to the well known experience that mixed ligand complexes formed by a divalent 3d ion, a heteroaromatic N base and an O donor ligand possess increased stability. The stability constants of the 1:1 complexes formed between Cu2+, Cu(Bpy)2+ or Cu(Phen)2+ and L2-, were determined by potentiometric pH titration in aqueous solution (I = 0.1 M, NaNO3, 25?C). The order of the stability constants was reported. A comparative investigation between ternary complexes of Trp, Ttr, and Gly is made. The comparison of stability constants of these ternary complexes show that Cu(Har)(Trp) is found near 100% in closed form but Cu(Har)(Gly) exists in open form. The differences between the above mentioned stability constants are based on stacked form of Cu(Har)(Trp). The last provides increased stability.

Complex Bilding Behavior of 2 ((4-Methyl-5-Nitro-6- (Pyrolidine-1-yl)Pyrimidine-2-yl)Amino)Propionic Acid in Aqueous Solution

The acidity constants of MNPPAP1 were determined by potentiometric pH titration. The stability constants of the 1:1 complexes formed between M2+: Ca2+, Mg2+, Mn2+, Co2+, Ni2+, Cu2+ or Zn2+ and MNPPAP2-, were determined by potentiometric pH titration in aqueous solution (I =0.1 M, NaNO3, 25℃). The order of the stability constants was reported. It is shown that the stability of the binary M(MNPPAP) complexes is determined by the basicity of the carboxyl or amino group. All the stability constants reported in this work show the usual trend. The obtained order is Ca2+ 2+ > Mn2+ Co2+ Ni2+ Cu2+ > Zn2+. The observed stability order for MNPPAP follows approximately the Irving-Williams sequence. It is shown that regarding to M ion-binding properties vital differences on complex bilding were considered. It is demonstrated, that in M-MNPPAP complexes, M ion is coordinated to the carboxyl group, M ion is also able to bild macrochelate over pyrimidine group. The up mentioned results demonstrate that for M-MNPPAP complex the stability constants is also largely determined by the affinity of M2+ for carboxyl group. It is shown that MNPPAP can exert a direct influence on reaction mechanism through different kinds of metal ions and donor groups of MNPPAP.