Stepwise Encapsulation of Sulfate Ions by Ferrocenyl‐Functionalized Tripodal Hexaurea Receptors. Issue 27 (15th May 2013)

• Record Type: Journal Article
• Authors: Huang, Xiaojuan; Wu, Biao; Jia, Chuandong; Hay, Benjamin P.; Li, Minrui; Yang, Xiao‐Juan
• Is Part Of: Chemistry. Volume 19:Issue 27(2013)
• Page Start: 9034
• Page End: 9041
• Publication Date: 2013-05-15
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201300275
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Three ferrocenyl‐functionalized tripodal hexaurea anion receptors with <italic>ortho</italic>‐ (<bold>L²</bold>), <italic>meta</italic>‐ (<bold>L³</bold>), and <italic>para</italic>‐phenylene (<bold>L⁴</bold>) bridges, which showed strong binding affinities toward sulfate ions, have been designed and synthesized. In particular, <italic>meta</italic>‐phenylene‐bridged ligand <bold>L³</bold>, owing to its trigonal bipyramidal structure, can encapsulate two SO₄²⁻ ions in its "inner" and "outer" tripodal clefts, respectively, as supported by their clearly distinct NMR resonances and by molecular modeling. The sulfate complex of <italic>ortho</italic>‐ligand <bold>L²</bold>, (TBA)₂[SO₄⊂<bold>L²</bold>]<bold>⋅</bold>2 H₂O (<bold>1</bold>), displays a caged tetrahedral structure with an encapsulated sulfate ion that is hydrogen bonded by the six urea groups of ligand <bold>L²</bold>. CV studies showed two types of electrochemical response of the ferrocene/ferrocenium redox couple upon anion binding, that is, a shift of the wave and the appearance of a new peak. Quantitative binding data were obtained from the NMR and CV titrations.</p> </abstract>