Complexes of Gallium(iii) With Hydroxyaromatic Ligands

Abstract

The equilibria between gallium(II1) ion and selected hydroxyaromatic and dihydroxyaromatic ligands at 2S"C, p = 0.100 M (KNO,) have been determined. Potentiometric measurements on 1: 1,2: 1, and 3: 1 molar ratios of ligand to Ga(II1) have been made as a function of degree of neutralization over the entire accessible -log [H'] scale. Calculations were carried out so as to take account of competing hydrolytic reactions, and formation constants of gallium(II1) with chromotropic acid, 8-hydroxyquinolineS-sulfonic acid, 5-sulfosalicylic acid, and 1,2-dihydroxybenzene-3,5-disulfonic acid were obtained. Stable hydroxo chelates do not form under the reaction conditions employed. The protonation constants of the ligands and the formation constants of the gallium chelates are discussed and compared with previously published work on these gallium chelates and on chelates of "analogous" metal ions such as those of Fe(II1) and AI(II1).

Iron(III) Chelation: Tuning of the pH Dependence by Mixed Ligands

“…[9] The values of the lowest protonation constants (1.8 and 2.89 for L 1 ; 2.34 for L 2 ) correspond to the pyridine nitrogen of the sulfohydroxyquinoline moieties. Compared to 8-hydroxyquinoline-5-sulfonic acid (log K H ϭ 3.93), [10] the protonation constants determined for L 1 and L 2 are two orders of magnitude lower. This could be explained by the electron-withdrawing effect of the carbonyl linker in position 7, which is similar to that of the nitro group in 7-nitro-8-hydroxyquinoline-5-sulfonic acid (log K H ϭ 2.01).…”

“…This could be explained by the electron-withdrawing effect of the carbonyl linker in position 7, which is similar to that of the nitro group in 7-nitro-8-hydroxyquinoline-5-sulfonic acid (log K H ϭ 2.01). [11] The hydroxyl protonation constant of 8-hydroxyquinoline-5-sulfonic acid [10] 2 which showed an inflection point at pD ഠ 6 and a significant upfield shift of the methylene protons, characteristic of the protonation of its closest acid-base site, i.e. the tertiary amine (Figure 3).…”

Chromotropic acid, a fluorogenic chelating agent for aluminium(III)

“…The corresponding stability constants for the 1:1 and 1:2 chelates were reported to be either a little larger [32], or somewhat smaller [37] than the stability constants of the aluminium chelates. Nevertheless, fluorogenic ligands of Al(III) are fluorogenic ligands of Ga(III), the properties of the absorption bands and of the fluorescence emission being generally quite similar [19].…”

Rákellenes gallium- és platinafém komplexek oldatkémiája, kölcsönhatásuk vérszérum-fehérjékkel és DNS-sel

“…A pK 1 feltehetőleg a kinolin NH + deprotonálódásához tartozik, míg a második lépcsőzetes deprotonálódási folyamat a fenolos hidroxilcsoporthoz köthető. Az általunk vizes közegben meghatározott állandók jó egyezést mutatnak az irodalomban található más körülmények között mért állandókkal [163][164][165]. Az oxin pK a -i valamivel nagyobbak, mint a szulfoxiné mivel a szulfonát elektronszívó csoport.…”

“…(5.6.1. táblázat). Az oxin és szulfoxin ligandumok kétfogúan (N,O) donorként koordinálódnak a fémionhoz [64,164].…”