Organoboron compounds as Lewis acid receptors of fluoride ions in polymeric membranes

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• 作者：Martyna Ja艅czyk^a ; Agnieszka Adamczyk-Wo藕niak^b ; Andrzej Sporzy艅ski^b ; Wojciech Wró ; blewski^a ; ^{wuwu@ch.pw.edu.pl}
• 关键词：Organoboron compounds ; Boronic acids ; Lewis acid receptors ; Fluoride receptors ; Ion-selective electrodes
• 刊名：Analytica Chimica Acta
• 出版年：2012
• 期刊代码：2_00032670
• 类别：ch
• 出版时间：6 July, 2012
• 卷：733
• 期：Complete
• 页码：71-77
• 文件大小：589 K

摘要

Newly synthesized organoboron compounds - 4-octyloxyphenylboronic acid (OPBA) and pinacol ester of 2,4,6-trifluorophenylboronic acid (PE-PBA) - were applied as Lewis acid receptors of fluoride anions. Despite enhanced selectivity, the polymer membrane electrodes containing the lipophilic receptor OPBA exhibited non-Nernstian slopes of the responses toward fluoride ions in acidic conditions. Such behavior was explained by the lability of the B-O bond in the boronic acids, and the OH^{鈭?/sup>/F鈭?/sup> exchange at higher fluoride content in the sample solution. In consequence, the stoichiometry of the OPBA-fluoride complexes in the membrane could vary during the calibration, changing the equilibrium concentration of the primary anion in membrane and providing super-Nernstian responses. The proposed mechanism was supported by 19F NMR studies, which indicated that the fluoride complexation proceeds more effectively in acidic solution leading mainly to PhBF₃鈭?/sup> species. Finally, the performances of the membranes based on the phenylboronic acid pinacol ester, with a more stable B-O bond, were tested. As it was expected, Nernstian fluoride responses were recorded for such membranes with worsened fluoride selectivity.}