Equilibrium Studies of the Ternary Complex Systems Mⁿ⁺ + Dipicolinic Acid + N-(2-Acetamido)iminodiacetic Acid or Amino Acids

Abstract

Complex formation in the ternary systems M n + + dipicolinic acid + amino acids or N-(2-acetamido)iminodiacetic acid (H2ADA), where M n + = CuII, ZnII, NiII, CoII, HgII, CdII, PbII, UO2 II, YIII, and CeIII, have been investigated pH-metrically in aqueous media at 25 °C and at ionic strength I = 0.10 mol dm-3 (KNO3). The stability constants of the different binary and ternary complexes formed in such systems have been determined and discussed in terms of the nature of both metal ion and secondary ligand (amino acids or H2ADA). It was deduced that, except in the case of dicarboxylic amino acid, the stability of the ternary complex is lower than that of the corresponding binary M n + + amino acid or H2ADA.

Solution Equilibria of Binary and Ternary Systems Involving Transition Metal Ions, Adenosine 5‘-Triphosphate, and Amino Acids

“…The formation constant (log K) values of the different 1:1 and 1:2 binary complexes (Table 1) were determined by applying the original equations of Irving and Rossotti to the binary complex solution systems (curves b, c and d, e for [M(aa)] (n-m) and [M(ATP) k ] (n-4k) , respectively. Some of the log K values are in good agreement with those found in the literature (Mahmoud et al, 1989a,b;Ahmed et al, 1996;Krishna and Ram, 1991;Martell and Sillen, 1971). …”

“…c Mahmoud et al, 1989. d Martell and Sillen, 1971. e Krishna and Ram, 1991. f Ahmed et al, 1996. The data cited in Table 2 indicate that the stability of the 1:1:1 mixed ligand complexes of the same ligand is higher than that of the corresponding 1:2:1 ternary complexes.…”

“…Moreover, no studies appear to have been made on the ternary systems of the trivalent transition metal ions containing ATP and amino acid ligands. Continuing our studies on the mixed ligand complexes (Ahmed et al, 1996(Ahmed et al, , 1997(Ahmed et al, , 1998, this paper represents a systematic potentiometric study on the complex formation between some transition metal ions (Cu II , Ni II , Co II , La III , and Ce III ) and adenosine 5′-triphosphate, in the form of the disodium salt (H 2 L) 2-, as a primary ligand and some monocarboxylic as well as dicarboxylic amino acids (proline, lysine, histidine, asparagine, glutamine, aspartic acid, and glutamic acid) as secondary ligands in aqueous media at (25 ( 0.1)°C. The structures of the ligands used in this study are…”

Stripping chronopotentiometry at scanned deposition potential (SSCP). Part 8. Metal speciation analysis in gels

“…c à PbðIIÞ ¼ 4  10 À7 mol dm À3 , t d = 300 s, I s = 5 · 10 À11 A. Table 2 Comparison of calculated speciation and Donnan partitioning in the Pb(II)-PCA system with that measured at a gel-coated microelectrode absence of gel coating) in agreement with the literature data corrected to this ionic strength [37,38]. Data measured at a gel-coated microelectrode at I = 1 and 10 mmol dm À3 are given in Table 3 and Fig.…”

Binary Complexes of Aspartic Acid with Some Metal Ions in Aqueous Solution and Water-dioxane Mixtures

“…Negative ∆H°s conveys that the reactions are exothermic, and negative ∆S° are the indication that the complexes are more organized than the reactants. Some workers have conducted research on complex systems of mixed ligands as ternary complexes with transition metal ions which needed sophisticated softwares and more rigorous treatment of data [47][48][49][50][51].…”