Synthetic, structural, spectroscopic and solution speciation studies of the binary Al(III)–quinic acid system. Relevance of soluble Al(III)–hydroxycarboxylate species to molecular toxici

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• 作者：Catherine Gabriel ; Melita Menelaou ; Markos Daskalakis ; Andrea Lakatos ; Tamas Kiss ; Constantin Mateescu ; Raphael G. Raptis ; Panagiotis Zoumpoulakis ; Athanasios Salifoglou
• 关键词：Aluminum– ; quinate interactions ; Structural speciation ; X-ray structure ; Solid-state and solution NMR ; Aluminum toxicity
• 刊名：Polyhedron
• 出版年：2008
• 出版时间：10 September 2008
• 年：2008
• 卷：27
• 期：13
• 页码：2911-2920
• 全文大小：580 K

文摘

Efforts to delineate the interactions of Al(III), a known metallotoxin, with low molecular mass physiological substrates involved in cellular processes led to the investigation of the structural speciation of the binary Al(III)–quinic acid system. Reaction of Al(NO₃)₃ · 9H₂O with d-(−)-quinic acid at a specific pH (4.0) afforded a colorless crystalline material K[Al(C₇H₁₁O₆)₃] · (OH) · 4H₂O (1). Complex 1 was characterized by elemental analysis, FT-IR, DSC–TGA, ¹³C-MAS NMR, solution ¹H and ¹³C NMR, and X-ray crystallography. The structure of 1 reveals a mononuclear octahedral complex of Al(III) with three singly ionized quinate ligands bound to it. The three ligand alcoholic side chains do not participate in metal binding and dangle away from the complex. The concurrent study of the aqueous speciation of the binary Al(III)–quinic acid system projects a number of species complementing the synthetic studies on the binary system Al(III)–quinic acid. The structural and spectroscopic data of 1 in the solid state and in solution emphasize its physicochemical properties emanating from the projections of the aqueous structural speciation scheme of the Al(III)–quinic acid system. The employed pH-specific synthetic work (a) exemplifies essential structural and chemical attributes of soluble aqueous species, arising from biologically relevant interactions of Al(III) with natural α-hydroxycarboxylate substrates, and (b) provides a potential linkage to the chemical reactivity of Al(III) toward O-containing molecular targets influencing physiological processes and/or toxicity events.