Madhup Chandra

Ternary complexes of copper(II), nickel(II) and zinc(II) with nitrilotriacetic acid as a primary ligand and some phenolic acids as secondary ligands

SummaryThe formation of ternary complexes of the MAL3− type [where M = CuII, NiII and ZnII ; A = nitrilotriacetic acid (NTA); L = 1-hydroxy-2-naphthoic acid (1,2 HNA) and 2-hydroxy-1-naphthoic acid (2,1 HNA)] have been studied potentiometrically in 50% v/v aqueous — ethanol (25° and µ = 0.1). Under identical conditions the binary complexes of the 1,2- and 2,1-HNA ligands have also been examined. The values of mixed ligand formation constants KMAL have been found to be lower than KML (first step formation constant of binary complexes) and even less than

Biologically important compounds as ligands: Binary and ternary complexes of 5-amino-7-hydroxy-triazolo[4,5—d]pyrimidine (“8-azaguanine”) in solution

K_{ML_2 }

Biligand metal chelates of 1,10-phenanthroline and several salicyclic acid derivatives in solution

(second step formation constant of binary complexes).

Biologisch relevante Verbindungen als Liganden: Binre und ternre Komplexe von 5-Amino-7-hydroxy-triazolo[4,5-d]pyrimidin (?8-Azaguanin?) in Lsung

Chelating tendencies of several biologically important compounds viz. glycocyamine (GCN:N-amidino-aminoethanoic acid) taurine (TRN: 2-aminoethanesulphonic acid) and pyridoxal [PDL; 3-hydroxy-5-(hydroxymethyl)-2-methyl-pyridine-4-carbaldehyde] have been examined by pH-metric titration technique in their binary complex formation with copper(II) and uranyl(VI) ions. The work has further been extended to investigating the ternary complex formation involving 2,2′-bipyridine, 1,10-phenanthroline or nitrilotriacetic acid as a primary andTRN andPDL as secondary ligands. All the experiments were carried out at 25 °C and at an ionic strength of 0.1M (NaClO4) in aqueous or 50% (v/v) aqueous-ethanol medium according to the suitability of the experimental conditions. Stabilities of ternary complexes as compared to those of the corresponding binary complexes of the secondary ligands have also been discussed.ZusammenfassungDas Komplexierungsvermögen einiger biologisch wichtiger Verbindungen [Glycocyamin (GCN:N-Amidino-aminoethansäure), Taurin (TRN; 2-Amino-ethansulfonsäure und Pyridoxal (PDL; 3-Hydroxy-5-(hydroxymethyl)-2-methyl-pyridin-4-carbaldehyd)] gegenüber Kupfer(II)- und Uranyl(VI)-Ionen wurde untersucht. FürTRN undPDL wurde das System auf ternäre Komplexe erweitert (2,2′-Bipyridin, 1,10-Phenanthrolin und Nitrilotriessigsäure als Primärligand). Die Messungen wurden bei 25 °C und bei Ionenstärken von 0,1M(NaClO4) in Wasser oder 50% Wasser—Ethanol durchgeführt. Die Stabilität der ternären Komplexe im Vergleich zu den entsprechenden binären wird diskutiert.

Binre Kupfer(II)- und Uranyl(VI)-Komplexe von Glycocyamin, Taurin und Pyridoxal; Erweiterung zu ternren Systemen mit 2,2?-Bipyridin, 1,10-Phenanthrolin und Nitrilotriessigsure

Metal complexation equilibria in the binary complexing systems of the typeM−L [M=Cu(II), Ni(II), Co(II), Zn(II), Cd(II), and UO2(VI);L=AZN=8-azaguanine] have been examined potentiometrically. The work has further been extended to investigating the ternary complexing systems of the typeM−A−L [A=2,2′-bipyridine, 1,10-phenanthroline or nitrilotriacetic acid]. Measurements were done at 25°C and at an ionic strength of 0.1M (NaClO4) in 50% (v/v) aqueous ethanol medium. Stabilities of the ternary complexes as compared to those of the corresponding binary complexes ofAZN are also discussed.ZusammenfassungEs wurden Komplexierungsgleichgewichte vom binären TypM−L [M=Cu(II), Ni(II), Co(II), Zn(II), Cd(II) und UO2(VI);L=AZN=8-Azaguanin] potentiometrisch untersucht. Die Untersuchungen wurden auf ternäre Systeme vom TypM−A−L ausgedehnt [A=2,2′-Bipyridin, 1,10-Phenanthrolin oder Nitrilotriessigsäure]. Die Messungen wurden bei 25°C bei Ionenstärken von 0,1M (NaClO4) in 50% wäßr. Ethanol durchgeführt. Die Stabilität der ternären Komplexe im Vergleich zu den entsprechenden binären wird diskutiert.

MIXED LIGAND CHELATES OF COPPER(II), ZINC(II), NICKEL(II) AND COBALT(II) WITH NITRILOTRIACETIC ACID AS THE PRIMARY LIGAND AND 3,5-DINITRO- AND 3,5-DIBROMOSALICYCLIC ACIDS AS SECONDARY LIGANDS

SummaryTernary complex-forming systems of the type Cu(A)L (A = 2,2′-dipyridyl and L = 2,4-dihydroxybenzoic acid,o-cresotic acid and 2-hydroxy-3-naphthoic acid) have been examined potentiometrically in 50% v/v aqueous ethanol. Various stability constants have been measured.