Gm. Escandar et al., INTERACTION OF ZINC(II) ION WITH D-ALDONIC ACIDS IN THE CRYSTALLINE SOLID AND AQUEOUS-SOLUTION, Polyhedron, 13(6-7), 1994, pp. 909-914
The interaction of zinc(II) ion with D-glucoheptonic acid, D-gluconic
acid, D-gulonic acid, D-galactonic acid and D-ribonic acid has been in
vestigated and compounds of the type Zn(D-glucoheptonate)2 . 3H2O. Zn(
D-gluconate)2 . 3H2O, Zn(D-gulonate)2 . 3H2O, Zn(D-galactonate)2 . 3H2
O and Zn(D-ribonate)2 . H2O, have been isolated. These metal-sugar sal
ts were characterized by elemental analysis, FT IR spectroscopy, therm
ogravimetric analysis and C-13-NMR. Spectroscopic measurements showed
similar patterns between these complexes and the structurally identifi
ed Mn(D-gluconate)2 . 2H2O. The zinc(II) ion is binding to two ligand
molecules through the carboxylate and OH groups of each sugar, as well
as to water molecules. The potentiometric measurements in aqueous sol
utions for the systems formed by the sugar acids investigated and the
zinc(II) ion at different metal-ligand ratios showed the 1 : 1 complex
es formation. On the basis of the C-13 NMR, the participation of C-1 a
nd C-2 in this complex formation was verified. Due to the hydroxide pr
ecipitation, quantitative evaluation of the stability constants was no
t performed.