The complexation of metal cations by D-galacturonic acid: a spectroscopic study.
Solid complexes of D-galacturonic acid (GalA) with cobalt(II), copper(II), nickel(II) and oxovanadium(IV) (1-4) were prepared and characterised. The metal-to-ligand molar ratio was 1:2 for complexes 1-3 and 1:1 for complex 4. The alpha- and beta-anomers of GalA were detected in all the complexes in solid state and in solutions. An addition of small amounts of the paramagnetic complexes to the D2O solution of pure ligand led to NMR line broadening of some 1H and 13C nuclei. This broadening was sensitive to the anomeric state of GalA in the case of complexes 1 and 4. NMR and vibrational spectroscopic data indicate the formation of carboxylate complexes of all the cations, while noncarboxylic oxygens are also involved into the metal bonding in some cases. VCD spectra of complexes 1-4 in D2O and Me2SO-d6 solutions confirm that GalA carboxylic group may participate in the formation of optically active species around the metal cation. Possible ways of GalA coordination by metal cations of this study were proposed and discussed.
Synytsya
Andriy
A
Department of Carbohydrate Chemistry and Technology, Institute of Chemical Technology, Technická 3/5, 166 28 Prague 6, Czech Republic. sinicaa@vscht.cz
Urbanová
Marie
M
Setnicka
Vladimír
V
Tkadlecová
Marcela
M
Havlícek
Jaroslav
J
Raich
Ivan
I
Matejka
Pavel
P
Synytsya
Alla
A
Copiková
Jana
J
Volka
Karel
K
D002413:Cations, Divalent / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D019216:Metals, Heavy / Q000737:chemistry*; D015394:Molecular Structure; D012996:Solutions
D002413:Cations, Divalent; D006603:Hexuronic Acids; D019216:Metals, Heavy; D012996:Solutions; C007819:galacturonic acid