Department of Natural Sciences, The Open University of Israel, 1 University road, P.O. Box 808, Ra'anana, 4353701, Israel.
Schulich Faculty of Chemistry, Technion: Israel Institute of Technology, Technion city, Haifa, 3200001, Israel.
Chemistry. 2019 Oct 17;25(58):13336-13343. doi: 10.1002/chem.201901822. Epub 2019 Sep 5.
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 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.
杯芳烃（BUs）是刚性的主体化合物，具有伸展的、类似曲柄的构象，并且 BU[6] 强烈地将阴离子结合在其疏水腔内。这些特征不一定为过硫杯芳烃家族所共有。本研究表明，过硫杯芳烃呈现出紧凑的构象，而过硫 BU[6] 是阴离子的不良结合物，从含有卤化物盐的溶液中结晶为无阴离子的物质。计算研究表明，赤道硫原子通过强范德华（vdW）吸引相互作用与甘脲亚甲基竞争与客体阴离子结合。这些竞争性接触不仅解释了过硫杯芳烃阴离子结合能力的降低，也解释了它们紧凑的构象。半硫代和过硫代 BU[4] 与 Hg 在固态中形成线性配位聚合物，无论其固有分子构象如何。硫原子在分子内相互作用中的强烈参与将赤道与轴向（外围）杂原子区分开来，从而提供化学选择性和区域选择性转化。
