Haino Takeharu, Kobayashi Mutsumi, Fukazawa Yoshimasa
Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
Chemistry. 2006 Apr 12;12(12):3310-9. doi: 10.1002/chem.200500976.
The synthesis and spectroscopic characterization of a cavitand-based coordination capsule 14 BF4 of nanometer dimensions is described. Encapsulation studies of large aromatic guests as well as aliphatic guests were performed by using 1H NMR spectroscopy in [D1]chloroform. In addition to the computational analysis of the shape and geometry of the capsule, an experimental approach to estimate the interior size of the cavity is discussed. The cavity provides a highly rigid binding space in which molecules with lengths of approximately 14 A can be selectively accommodated. The rigid cavity distinguished slight structural differences in the flexible alkyl-chain guests as well as the rigid aromatic guests. The detailed thermodynamic studies revealed that not only CH-pi interactions between the methyl groups on the guest termini and the aromatic cavity walls, but also desolvation of the inner cavity play a key role in the guest encapsulation. The cavity preferentially selected the hydrogen-bonded heterodimers of a mixture of two or three carboxylic acids 18-20. The chiral capsule encapsulated a chiral guest to show diastereoselection.
描述了一种基于空穴配体的纳米尺寸配位胶囊14 BF₄的合成及光谱表征。通过在[D₁]氯仿中使用¹H NMR光谱对大的芳香族客体以及脂肪族客体进行了包封研究。除了对胶囊的形状和几何结构进行计算分析外，还讨论了一种估计空腔内部尺寸的实验方法。该空腔提供了一个高度刚性的结合空间，长度约为14 Å的分子可被选择性容纳。刚性空腔区分了柔性烷基链客体以及刚性芳香族客体的细微结构差异。详细的热力学研究表明，不仅客体末端甲基与芳香族空腔壁之间的CH-π相互作用，而且内腔的去溶剂化作用在客体包封中起关键作用。该空腔优先选择两种或三种羧酸18 - 20混合物的氢键异二聚体。手性胶囊包封手性客体以表现出非对映选择性。
