Berrocal M J, Cruz A, Badr I H, Bachas L G
Department of Chemistry, University of Kentucky, Lexington 40506-0055, USA.
Anal Chem. 2000 Nov 1;72(21):5295-9. doi: 10.1021/ac000241p.
Ionophore topology has a profound effect on the behavior of ion-selective electrodes. This is demonstrated with a new class of ionophores that incorporates aminochromenone moieties linked through urea spacers to different scaffolds that preorganize the ionophore binding cleft into tripodal topologies. Tris(2-aminoethylamine) and cis-1,3,5-tris(aminomethyl)cyclohexane were employed as the scaffolds. The two differ in their rigidity and in the size of ionophore cavity that they create. The electrodes based on the ionophore that incorporates the tris(2-aminoethylamine) scaffold show anti-Hofmeister behavior with an improved selectivity for sulfate. In contrast, the ionophore with the cis-1,3,5-tris(aminomethyl)cyclohexane scaffold exhibits a more Hofmeister-like response.
离子载体的拓扑结构对离子选择性电极的行为有着深远影响。这一点通过一类新型离子载体得到了证明，这类离子载体包含通过脲间隔基连接到不同支架上的氨基色酮部分，这些支架将离子载体的结合裂隙预组织成三脚架拓扑结构。三（2-氨基乙胺）和顺式-1,3,5-三（氨甲基）环己烷被用作支架。两者在刚性以及它们所形成的离子载体腔的大小方面存在差异。基于包含三（2-氨基乙胺）支架的离子载体的电极表现出抗霍夫迈斯特行为，对硫酸根具有更高的选择性。相比之下，具有顺式-1,3,5-三（氨甲基）环己烷支架的离子载体表现出更类似霍夫迈斯特的响应。
