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Anion‐Free Bambus[6]uril and Its Supramolecular Properties
Author(s) -
Svec Jan,
Dusek Michal,
Fejfarova Karla,
Stacko Peter,
Klán Petr,
Kaifer Angel E.,
Li Wei,
Hudeckova Edita,
Sindelar Vladimir
Publication year - 2011
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.201003683
Subject(s) - acetonitrile , chemistry , iodide , supramolecular chemistry , ion , halide , hydrogen peroxide , chloroform , inorganic chemistry , methanol , salt (chemistry) , crystal structure , crystallography , organic chemistry
Methods for the preparation of anion‐free bambus[6]uril (BU6) are presented. They are based on the oxidation of iodide anion, which is bound inside the macrocycle, utilizing dark oxidation by hydrogen peroxide or photooxidation in the presence of titanium dioxide. Anion‐free BU6 was found to be insoluble in any of the investigated solvents; however, it dissolves in methanol/chloroform (1:1) or acetonitrile/water (1:1) mixtures in the presence of the tetrabutylammonium salt of a suitable anion. The association constants with halide ions, BF 4 − , NO 3 − , and CN − , were measured by 1 H NMR spectroscopy. The highest association constant (8.9×10 5 M −1 ) was found for the 1:1 complex of BU6 with I − in acetonitrile/water mixture. A number of crystal structures of BU6 complexes with various anions were obtained. The influence of the anion size on the macrocycle diameter is discussed together with an unusual arrangement of the macrocycles into separate layers.