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Stepwise Encapsulation of Sulfate Ions by Ferrocenyl‐Functionalized Tripodal Hexaurea Receptors
Author(s) -
Huang Xiaojuan,
Wu Biao,
Jia Chuandong,
Hay Benjamin P.,
Li Minrui,
Yang XiaoJuan
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201300275
Subject(s) - encapsulation (networking) , sulfate , ion , chemistry , organic chemistry , computer science , computer network
Three ferrocenyl‐functionalized tripodal hexaurea anion receptors with ortho ‐ ( L 2 ), meta ‐ ( L 3 ), and para ‐phenylene ( L 4 ) bridges, which showed strong binding affinities toward sulfate ions, have been designed and synthesized. In particular, meta ‐phenylene‐bridged ligand L 3 , owing to its trigonal bipyramidal structure, can encapsulate two SO 4 2− 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 ortho ‐ligand L 2 , (TBA) 2 [SO 4 ⊂ L 2 ] ⋅ 2 H 2 O ( 1 ), displays a caged tetrahedral structure with an encapsulated sulfate ion that is hydrogen bonded by the six urea groups of ligand L 2 . 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.