Role of Biologically Important Zwitterionic Buffer Secondary Ligands in the Stability of the Ternary Complexes Containing Some Metal Ions and Guanosine 5‘-Monophosphate, Inosine 5‘-Monophosphate, and Cytidine 5‘-Monophosphate

2001 ◽  
Vol 46 (1) ◽  
pp. 34-40 ◽  
Author(s):  
Zeinab M. Anwar ◽  
Hassan A. Azab
Keyword(s):  
Metal Ions ◽  
Ternary Complexes ◽  
The Stability ◽  
Zwitterionic Buffer

scholarly journals Complex Equilibria and Distribution of Metal (II) Ions with Biologically Active Chelating Agents in Aqueous and Aqueous-organic Media

2021 ◽  
pp. 25-38
Author(s):  
K. T. Ishola ◽  
O. T. Olanipekun ◽  
O. T. Bolarinwa ◽  
R. D. Oladeji ◽  
A. Abubakar
Keyword(s):  
Metal Ions ◽  
Species Distribution ◽  
Ternary Complex ◽  
Aqueous System ◽  
Ternary Complexes ◽  
Teller Distortion ◽  
Complex Equilibria ◽  
Binary Complexes ◽  
The Stability ◽  
Ph Range

An understanding of the principles of complex equilibria and species distribution in different solutions is important in expounding and correlating the interaction of different ligands with different metal ions in complex formation. Therefore, acid-base equilibria involved in the formation of binary and ternary complexes of Co (II), Cu (II) and Pb (II) with methionine (Met) and uracil (Urc) have been determined by potentiometric titration technique. The stability constants of the complexes were evaluated at 35 ± 0.1°C and 0.02 M ionic strength (kept constant with NaNO3) in aqueous and organic-aqueous media. The species distribution in solutions as a function of pH was determined using the Hyss program. The stability of the ternary complexes relative to the corresponding binary complexes of the secondary ligand is measured in terms ΔlogK and % RS values. The ternary complexes are observed to be more stable than binary complexes in the media except for [CuMetUrc] ternary complex in organic-aqueous medium where the ternary complex is less stable than the binary complex of the uracil. The overall stability of the ternary complexes was higher in organic-aqueous system than aqueous system. The stability of the complexes was found to be correlated with the covalent index of the metal ions and Jahn Teller distortion. pH-studies of these systems revealed an increase in the concentrations of the ternary complexes with increase in pH. The formation of binary complexes was shown to be favoured in physiological pH range (3-7) while that of the ternary complexes is observed to be favoured in the pH range 5-10.

scholarly journals Coordination properties of N,O-carboxymethyl chitosan (NOCC). Synthesis and equilibrium studies of some metal ion complexes. Ternary complexes involving Cu(II) with (NOCC) and some biorelevant ligand

2012 ◽  
Vol 10 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Azza Shoukry ◽  
Wafaa Hosny
Keyword(s):  
Metal Ions ◽  
Stability Constants ◽  
Metal Ion ◽  
Ternary Complexes ◽  
Central Metal ◽  
Magnetic Studies ◽  
Complex Formation Equilibria ◽  
Equilibrium Studies ◽  
The Stability ◽  
Solid Complexes

AbstractIn the present study, the acid-base equilibria of N,O-carboxymethy chitosan abbreviated as (NOCC), is investigated. The complex formation equilibria with the metal ions Cu(II), Ni(II), Co(II), Mn(II), and Zn(II) are investigated potentiometrically. The stability constant values of the binary and ternary complexes formed in solution were determined and the binding centers of the ligands were assigned. The relationships between the properties of the studied central metal ions as ionic radius, electronegativity, atomic number, and ionization potential, and the stability constants of the formed complexes were investigated in an effort to give information about the nature of chemical bonding in complexes and make possible the calculation of unknown stability constants. Cu(II), Ni(II), and U(VI) complexes with NOCC are isolated as solid complexes and characterized by conventional chemical and physical methods. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies. The ternary copper(II) complexes involving NOCC and various biologically relevant ligands containing different functional groups, as amino acids and DNA constituents are investigated. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated.

scholarly journals Composition and stability of complexes of Ephedrine hydrochloride with Ni2+, Zn2+, and Cd2+ as toxic ions

2003 ◽  
Vol 71 (2) ◽  
pp. 75-88
Author(s):  
Nabawia EL Guindi
Keyword(s):  
Metal Ions ◽  
Chelating Agent ◽  
Cadmium Ions ◽  
Nickel Zinc ◽  
Ephedrine Hydrochloride ◽  
Stability Of Complexes ◽  
Different Temperatures ◽  
The Stability

The complexes of Ephedrine with Nickel, Zinc and Cadmium ions have been investigated spectrophotometricalfy using the method of corresponding solutions [I-3] and pH-metrically using Irving and Rossoti technique [4] Two compositions were observed spectrophotometrically 1 : 1 and 2: 1 (L: M) for concentration of metal ions (0.5 x 10-3 M and 1 x 10-3 M) hile the first composition only predominate at concentration of metal ions (1.5 x 10-3 M and 2 x 10-3 M ). The stability of complexes show that complexes of Ni2+ are more stable than that of Zn2+ an Cd2+, Moreover, the composition and stabilities of complexes were studied pHmetrically in aqueous medium at 0.1 M NaCl and two different temperatures 30°C and 40°C; hence the value of the free energy change (ΔG°), the enthalpy (ΔH°) and the entropy (ΔS°) were calculated at 30°C. Beside the role of Ephedrine as chelating agent to toxic elements, the complexometric method was used for the determination of Ephedrine in its pure form and in tablets.

scholarly journals The interaction of copper(II) and glycyl-l-histidyl-l-lysine, a growth-modulating tripeptide from plasma

1981 ◽  
Vol 199 (3) ◽  
pp. 649-656 ◽  
Author(s):  
S J Lau ◽  
B Sarkar
Keyword(s):  
Stability Constants ◽  
Equilibrium Dialysis ◽  
Physiological Role ◽  
Ternary Complexes ◽  
Low Molecular Weight ◽  
Visible Absorption ◽  
Multiple Species ◽  
The Stability ◽  
Ph Range

The interaction between Cu(II) and the growth-modulating tripeptide glycyl-L-histidyl-L-lysine in the presence and absence of L-histidine was investigated by potentiometric titration and visible-absorption spectrophotometry at 25 degrees C in 0.15 M-NaCl. Analyses of the results in the pH range 3.5--10.6 indicated the presence of multiple species in solution in the binary system and extensive amounts of the ternary complexes in the ternary system. The species distribution and the stability constants, as well as the visible-absorption spectra of the species, were evaluated. The combined results were used to propose the structure of some of the complexes. The influence of the epsilon-amino group of the peptide in the enhancement of the stability constants was reflected prominently when compared with those complexes formed by either glycyl-L-histidine or glycyl-L-histidylglycine. The results obtained from the equilibrium-dialysis experiments showed that this tripeptide was able to compete with albumin for Cu(II) at pH 7.5 and 6 degrees C. At equimolar concentrations of albumin and the peptide, about 42% of the Cu(II) was bound to the peptide. At the physiologically relevant concentrations of Cu(II), albumin, L-histidine and this peptide, about 6% of the Cu(II) was associated with the low-molecular-weight components. This distribution could be due to the binary as well as the ternary complexes. The possible physiological role of these complexes in the transportation of Cu(II) from blood to tissues is discussed.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

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