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Intramolecular van der Waals Interactions Challenge Anion Binding in perthio ‐Bambusurils
Author(s) -
Mondal Pravat,
Solel Ephrath,
Fridman Natalia,
Keinan Ehud,
Reany Ofer
Publication year - 2019
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.201901822
Subject(s) - van der waals force , intramolecular force , chemistry , heteroatom , ion , crystallography , sulfur , non covalent interactions , computational chemistry , stereochemistry , molecule , hydrogen bond , organic chemistry , ring (chemistry)
Bambusurils (BUs) are known to be rigid cavitands that feature an extended, jigger‐like conformation, and the BU[6]s strongly bind anions within their hydrophobic cavity. These features are not necessarily shared by the family of perthio ‐BUs. This study reveals that perthio ‐BUs assume a compact conformation and perthio ‐BU[6]s are poor anion binders, crystallizing as anion‐free species from solutions containing halide salts. Computational studies show that the equatorial sulfur atoms compete against guest anions for binding with the glycoluril methine groups via strong van der Waals (vdW) attractive interactions. These competitive contacts not only account for the diminished anion‐binding of perthio ‐BUs, but also explain their compact conformation. The semithio ‐ and perthio ‐BU[4]s form linear coordination polymers with Hg II in the solid‐state regardless of their intrinsic molecular conformation. The strong involvement of sulfur atoms in intramolecular interactions differentiates the equatorial from the axial (peripheral) heteroatoms, thus offering chemoselective and regioselective transformations.