| Abstract
| - The reactions of 2-quinaldic acid (2-QA) withtrivalent ions, Al3+, Fe3+, andGa3+, as well as divalent metal ions, Zn2+,Ni2+, Mn2+, and Co2+, werestudied. The trivalent metal ions provided the formulaQA4M2(μ-OH)2·S, where S= H2O or pyridine, while the divalent all provided aformula of QA2M·1.5H2O. TheQA4Ga2(μ-OH)2·4Pycomplex was characterized by single-crystal X-ray. Apolymer-supported version, PS-2-QA, selectively removedAl3+ ions from aqueous acidic solution in the presence ofother tri- and divalent metalions.
- The synthetic reactions of quinaldic acid (2-QA, 1), aligand with potential implications in Al3+ ionbiologicaltransport and in pharmaceutical applications and of use for the removaland recovery of Al3+ ions fromenvironmental waste sites, were studied with tri- and divalent metalions that encompass Al3+, Fe3+,Ga3+, Zn2+,Ni2+, Mn2+, and Co2+.The Al3+, Fe3+, and Ga3+metal ion complexes, 2−4, of 1 werecharacterized by FT-IR,FAB/MS, NMR, and elemental analysis and provided the followingstructural formula with 1 of2-QA4M2(μ-OH)2·S, where S = H2O or pyridine. Inthe case of the Ga3+ analog, 4·Py,the unequivocal μ-OH dimer structurewas determined by single-crystal X-ray analysis [space group,P1; a = 13.387(3) Å; b =14.016(2) Å; c =14.549(2) Å; α = 87.74(2)°; β = 73.44(2)°;γ = 82.61(2)°; Z = 2; volume = 2592.6Å3]. A description of theX-ray crystal structure of2-QA4Ga2(μ-OH)2·4pyridine, 4·Py, will also be presented. Thecorresponding bis(2-QA) metal complexes of Zn2+, Ni2+,Mn2+, and Co2+,5−8, were also studied and all provided aformula of2-QA2M·1.5 H2O, whichwere also characterized by many of the above-mentioned spectroscopictechniques.The polymer-supported (PS) version of 1,PS-2-QA, bonded to modified, macroporous 6%cross-linkedpolystyrene−divinylbenzene beads, was synthesized by an electrophilicsubstitution reaction on the aromatic ringof a 2-QA derivative, ethyl 2-quinaldate, with thechloromethylated precursor, PS-CH2Cl, followedby subsequentester hydroysis to the free PS-2-QA ligand. ThePS-2-QA ligand was found to selectively removeAl3+ ionsfrom aqueous acidic solution (pH = 3−5) in the presence of otherdivalent metal ions, namely, Cu2+, Zn2+,Ni2+,Mn2+, and Co2+ as well as a trivalent metalion, Cr3+.
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