title: Potentiometric and multinuclear NMR studies on the interaction of aluminum with ascorbic acid in acidic aqueous solution.
abstract: The complex-formation equilibria between aluminum(III) ion and L-(+)-ascorbic acid (AA) in 0.1 M KCl ionic medium at 25 degrees C and 0.15 M NaCl ionic medium at 37 degrees C were studied by glass electrode pH-metric measurements. The obtained experimental results were explained by the formation of the following complexation species: a weak mononuclear 1:1 species AlL(2+) together with two trinuclear mixed-hydroxo species Al(3)H(-5)L(4) and Al(3)H(-5)L(3+) in acidic aqueous solutions. Meanwhile, the formation of the complexes and structures of Al with AA were proved by multinuclear (1H, 13C, 27Al) NMR spectra in the pH range 2.0-5.0. It is supposed that Al directly coordinates with AA at O-3 moiety; also, Al can coordinate with the O-1 and O-2 moieties of ascorbate ion through the weakly binding and the intramolecular hydrogen bonding in acidic aqueous solutions.
authors.affiliation: State Key Laboratory of Coordination Chemistry, Department of Chemistry, Nanjing University, 22 Hankou Road, Nanjing 210093, People's Republic of China.
authors.forename: Xiaodi
authors.initials: X
authors.lastname: Yang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Miao
authors.forename: Tsing
authors.initials: T
authors.lastname: Yu
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.forename: Zhengbiao
authors.initials: Z
authors.lastname: Yang
authors.forename: Shuping
authors.initials: S
authors.lastname: Bi
mesh_terms: D000535:Aluminum / Q000737:chemistry* / Q000378:metabolism; D001205:Ascorbic Acid / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy
chemical_list: D000535:Aluminum; D001205:Ascorbic Acid