CODEN(USA): PCJHBA Potentiometric and conductometric studies of binary and ternary complexes of sulphamethoxazole and glycine with metal ions (original) (raw)
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Potentiometric Determination of Stability Constants of Sulphathiazole and Glycine-Metal Complexes
American Journal of Analytical Chemistry, 2018
Binary and ternary complexes of (Fe(III), Pb(II), Co(II), Al(III), La(III), Sr(II), Cr(III), Ti(II) and Zr(II)) with sulphathiazole (as primary ligand) and amino acid glycine (as secondary ligand) have been studied potentiometrically at 25˚C ± 0.1˚C and I = 0.1 M NaClO 4 in 25% (v/v) pure ethanol-water medium. Although there are many methods available to study the stability of metal-ligand complexes, pH-metry is most frequently used. In extension of our study on solution equilibria, we used Calvin-Bjerrum method for the calculation of stability constants. Stoichiometries and stability constants of binary systems containing the above metal ions in a 1:1 and 1:2 and/or 1:3 ratios were also determined to compare the effect of the secondary ligand on (1:1) Metal:Sulphathiazole system. The protonation constants of the complexes were evaluated for the system M:Sulphathiazole:Glycine = 1:1:1. The order of stability of the binary and ternary complexes was examined. It was found that glycine adds preferably [M-Sulfathiazole] rather than to the aqueous complexes of metal ions. In all cases 1:1:1 complex was formed.
Binary and ternary complexes of sulphamethoxazole
Monatshefte f�r Chemie Chemical Monthly, 1995
The complex formation equilibria involved in the binary and ternary systems M(II)-sulpha and M(II)-phen-sulpha were investigated by potentiometric titrations at 25 °C and a ionic strength of 0.1 N NaNO3 (M=Cu, Ni, Co, Zn; sulpha=sulphamethoxazole; phen=phenanthroline). The stability constants of the binary and ternary complexes follow the order of Irvin 9 and William. The formation of the ternary complex is discussed in terms of the binary species. The mode of chelation was ascertained by conductivity measurements.
Monatshefte f�r Chemie/Chemical Monthly, 2004
metal ions with some selected aliphatic and aromatic hydroxamic acids and some biologically important amino acids or nucleic acid components was investigated using the potentiometric technique at 25 C and I ¼ 0.10 mol dm À3 NaNO 3. The acid-base properties of the ligands were investigated and discussed. The acidity constants of the ligands were determined and used for determining the stability constants of the complexes formed in aqueous medium under the experimental conditions. The ternary complex formation was found to occur in a stepwise manner. The stability constants of these binary and ternary systems were calculated. The order of stability of the ternary complexes in terms of the nature of hydroxamic acid, amino acid, nucleic acid component and metal ions was investigated and discussed as well as the values of D log K and log X for the ternary systems. The concentration distribution of the various complex species in solution was evaluated. In addition, evaluation of the effect of temperature of the medium on the stability of the ternary system M III-benzohydroxamic acid-L-histidine or adenine (M III ¼ Fe III , Al III , and Cr III) has been studied. The thermodynamic parameters were calculated and discussed.
The Stability of Some Metal Complexes in Mixed Solvents
Canadian Journal of Chemistry, 1974
Acidity constants and stability constants of certain metal complexes (nickel(II), zinc(II), and manganese(II)) with ethylenediamine and glycine were determined at 25 °C and in 0.1 M ionic strength in mixed aqueous solutions of methanol (MeOH), dioxane (DOX), acetonitrile (MeCN), and dimethylformamide (DMF). In general, the stability constants of the metal complexes and the first protonation constant of glycine increase with increasing composition of the co-solvent in the order[Formula: see text]The protonation constants of ethylenediamine pass through a minimum at some particular solvent composition, while the second protonation constant of glycine exhibits behavior characteristic of the particular solvent employed.These results are discussed in terms of medium and solvent effects and properties of the solvent that might affect these, but find more satisfactory explanation in terms of solvent displacement during the association reactions. The observations can be accounted for in ter...
The chelation abilities of 2-aminophenol and 3,4-dihydroxybenzoic acid with divalent metal ions (Cu 2+ , Be 2+ , Zn 2+ , Ni 2+ , Co 2+ and Mn 2+ ) in binary and ternary systems at 37 ± 0.1°C and an ionic strength of 0.15 mol dm À3 NaCl were systematically investigated by using the potentiometric titration method. The chelating abilities of these complexes were obtained by processing the titration data using the Hyperquad2008 program and the results are presented as stability constants. In a binary system, it was shown that metal complexation involving 3,4-dihydroxybenzoic acid (ligand D) is more stable than the one with 2-aminophenol (ligand A). The stability of the formed metal complexes, both in binary and ternary systems, decreases in the following order: Cu 2+ > Be 2+ > Zn 2+ > Ni 2+ > Co 2+ > Mn 2+ . The tendency of these metals and ligands to form binary or ternary complexes was also evaluated and discussed by calculating their Dlog K M and log X values. In addition, the distribution of complex species in these systems was graphically presented using the HySS2009 program. UV-Vis spectrophotometry was also performed to qualitatively verify the protonation of these ligands and to confirm the model of the complex formed.
Bulletin of the Chemical Society of Ethiopia, 2003
Potentiometric study has been carried out on (S)-α-amino-3-hydroxy-5-methyl-4isoxazolepropanoic acid [AMPA] in the presence of transition metal ions to measure the thermodynamic stabilities of its complexes; and hence give an insight into its possible role in binding metal ions. The nitrogen donor atom of AMPA is alanine-like with the addition of a hydroxy-isoxazole ring. The first complex [CuHL], which is fully formed by pH 4 is proposed to be with {N,O} bonding which results in the formation of a stable five membered chelate ring. The [CuL] species has some enhanced stability which suggest some form of tridentate coordination through {H 2 N, COO-, O-}. When this changes to [CuL 2 ], one of these bonds must be broken if Cu(II) is to have a maximum coordination number of four. Zn and Cd formed very similar comlexes with AMPA, these were [ZnHL], [ZnL], [ZnL 2 ] and [CdHL], [CdL], [CdL 2 ], respectively. [ZnL] and [ZnL 2 ] are significantly more stable than alanine, suggesting tri-dentate coordination. [CdHL] complex is again very important suggesting some bidentate chelation.
The stabilities of ternary complexes of metal ions (copper, nickel, zinc and cobalt) with beta-hydroxy ketone(BHK) derivatives and benzotriazole(BTAZ) derivatives in various mixed solvent systems (Water+Ethyl Alcohol) medium in 0.1 M KNO3 ionic strength at 25 0 C using pH metric titration method have been established. The data reveal that the copper forms more stable complexes, which is followed by zinc and Ni complexes with these ligands. Cobalt form less stable complexes with these ligands. The stabilities of these complexes are further quantified with Δ log K values, intra-molecular equilibrium constants and percentage of stacking interaction in the ternary systems. The observed positive Δ log K values suggest that the flexible side chain alkyl moiety (ethyl group, butyl group) or aromatic moiety (phenyl group) in BHK ligand overlaps with the fixed aromatic moiety of BTAZ ligand in the ternary complex, which results in the enhanced stabilities for the (BHK-Alk)-Metal(II)-BTAZ and (BHK-Ph)-Metal(II)-BTAZ systems. Interestingly, the positive Δ log K values for both BHK-Alk and BHK-Ph ligands in their corresponding ternary complexes are about the same. This suggests the flexible Alkyl or phenyl side chain of BHK is overlapping with the triazole ring, but not the phenoxy ring of the BTAZ ligand.
Bulletin of Electrochemistry
Proton–ligand dissociation constants of 4-p-[N-2-(pyrimidyl) sulphonamino-phenylazo]-3-methyl-2-pyrazolin-5-one (I) and the stability constants of its complexes with some metal ions were determined potentiometrically in 0.1 M KCl and 30% (v/v) ethanol–water mixture. The order of the st abi l ity was found t o be Mn 2+ < Co 2+ < Ni 2+ < Cu 2+ < La 3+ < Hf 3+ < UO 2 2+ < Zr 4+ . The effect of temperature on the di ssoci at ion of (I) and the st abi l ity of i t s complexes were st udi ed. The corresponding t hermodynami c funct i ons were derived and di scussed. The di ssoci at ion process i s non-spont aneous, endothermi c and ent ropi cal l y unfavourable. The format ion of t he met al compl exes was found to be spontaneous, exothermi c and ent ropical ly f avourable.
Assiut University Journal of Multidisciplinary Scientific Research, 2015
The complex-formation of the copper(II), rhenium(V) and nickel(II) metal ions with 2mercaptobenzothiazole (MBT) have been investigated in 1 M hydrochloric acid. The compositions of complexes were determined, and their stepwise stability constants were calculated at 298, 308 and 318 K. The thermodynamic parameters such as, Gibb's free energy change (∆G), entropy change (∆S) and enthalpy change (∆H) associated with the complexation reactions were calculated and discussed. The dissociation process is non-spontaneous, endothermic and entropically unfavourable. The formation of the metal complexes has been found to be endothermic and entropically favourable.