surabhi sinha

Solution equilibria of homo an heterobinuclear complexes of Cu, Ni and Zn with iminodiacetic acid (IMDA = A 2- ) and L-pyrrolidine-2-carbox lic acid (proline = B - ) as ligands have been investigated by pH-measurements in an aqueous medium and relevant stability constants have been evaluated using computer technique. The stability constants of binary, ternary and qu ternary complexes are determined at 35 ± 1°C and at I = 0.1 mol dm -3 (NaNO 3 ). Complexes of the type [M 2 (A) 2 ( )] - and [M 1 M 2 (A) 2 (B)] - have been detected along with the various binary and ternary species. The observed order the stability constants and probable solution structure of homobinuclear complexes have been discussed.

A method is described for calculating equilibrium concentrations of all species in multi-metal-multi-ligand mixtures from the pH of the solution; total concentration of each metal, complexing agent, and the relevant equilibrium constants (pK(a) values and stability constants). Ternary and quaternary metal chelates of some biologically important bivalent transition metal ions viz. Co(II), Ni(II), Cu(II) and Zn(II) formed with biologically significant ligands, viz. IMDA/Uracil and Proline have been investigated. The relevant stability constants and complexation equilibria of quaternary metal chelates in solution at 37±1oC and at constant ionic strength (I=0.1M NaNO3) have been studied potentiometrically. Species distribution curves are obtained by plotting percent (%) concentration of the species obtained through SCOGS computer technique against pH. The distribution curves are finally sketched by running the computer programORIGIN 4.0. The metal ligand formation constant of ML1, ML2, ...

Investigation in solution exhibits the interest of chemist in thermodynamic aspects, which include knowledge of the stability constant of complexes with ligands of biochemical interest. It has been relevant for the experimental modeling of both reactions of metal ions with biomolecules and non-covalent interactions occurring in biological system. Stability constant data have been utilized to compute the equilibrium constant of ternary and quaternary complexes of citrulline/tryptophan and thymine with Cu(II), Zn(II) Co(II) and Ni(II) using SCOGS computer program at 37 ± 1 °C and in ionic strength I  = 0.1 M NaNO 3 . The metal–ligand formation constant of MA, MB, MAB and M 1 M 2 AB type of complexes follows Irving William order. The distribution curves of various complex species occurring at the different physiological pH have been discussed, and solution structures with an explanation of plausible equilibria have been proposed.

Metallic complexes of multimetal and multiligand systems are complicated for calculating equilibrium concentrations in solution. Complexation equilibria have been deduced on the basis of speciation curves obtained through SCGOS computer program. The formation constants of ternary(1:1:1) quaternary(1:1:1:1) complexes of CuII, PbII, HgII, CdII, ZnII, CoII and NiII with Glutamic acid(A) and Uracil(B) as ligands have been determined potentiometrically in aqueous medium.Study of metal complexes of said ligands with respect to their stability, solution structure and quantitative aspects has been done. Acid dissociation constants of the ligands used and the formation constants of the ternary and quaternary complexes were determined at 37±1°C and in ionic strength I = 0.1 M NaNO3. Different concentration of species as a function of pH was examined and sequence of overall stability constants for MA, MB, MAB and M1M2AB type of complexes have been discussed which seem to follow Irving William order.

An alternative multi-level programming technique based on fuzzy mathematical programming (FMP) is developed which gives better solutions than that proposed by Shih et al. (Comput. Oper. Res. 23(1) (1996) 73). The method uses the objectives in a sequential order of the hierarchy interactively and takes into account the desire of the DM at each stage. The technique is equally applicable

The earlier Karush–Kuhn–Tucker (KKT) transformation method has been applied to multi-level decentralized programming problems (ML(D)PPs) when the decision variable set was divided into subsets where each decision maker (DM) of the system controlled only a particular subset but had no control over any decision variables of some other subset. In this paper we give the mathematical formulation and corresponding development