Coordination chemistry of vitamin C. Part II. Interaction of L-ascorbic acid with Zn(II), Cd(II), Hg(II), and Mn(II) ions in the solid state and in aqueous solution.
The reaction of L-ascorbic acid with the zinc group and manganese ions has been investigated in aqueous solution at pH 6-7. The solid salts of the type M (L-ascorbate)2.2H2O, where M = Zn(II), Cd(II) and Mn(II) were isolated and characterized by 13C NMR and Fourier Transform infrared (FT-IR) spectroscopy. Spectroscopic evidence showed that in aqueous solution, the bindings of the Zn(II) and Mn(II) ions are through the ascorbate anion O-3 and O(2)-H groups (chelation), while the Cd(II) ion binding is via the O-3 atom only. In the solid state, the binding of these metal ions would be through two acid anions via O-3, O-2 of the first and O-1, O-3 of the second anion as well as to two H2O molecules, resulting in a six-coordinated metal ion. The Hg(II) ion interaction leads to the oxidation of the ascorbic acid in aqueous solution.
Tajmir-Riahi
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Photobiophysics Research Center, University of Quebec, Trois-Rivieres, Canada.
D000998:Antiviral Agents / Q000737:chemistry; D001205:Ascorbic Acid / Q000737:chemistry*; D002247:Carbon Isotopes; D002413:Cations, Divalent; D005583:Fourier Analysis; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008670:Metals / Q000737:chemistry*; D015394:Molecular Structure; D012996:Solutions; D013055:Spectrophotometry, Infrared / Q000379:methods; D014732:Vibration; D014867:Water
D000998:Antiviral Agents; D002247:Carbon Isotopes; D002413:Cations, Divalent; D008670:Metals; D012996:Solutions; D014867:Water; D001205:Ascorbic Acid