The host-guest complexation of six amine boranes (R3NBH3) by the macrocyclic host molecule cucurbit uril (CB ) in aqueous solution has been investigated using 1H and 11B NMR spectroscopy. The limiting complexation-induced 1H and 11B chemical shift changes indicate that the amine boranes are included in the hydrophobic cavity of the host molecule. The host-guest stability constants for neutral R3NBH3∙CB complexes (in the range of 105-107 ) have been determined by 1H NMR competition experiments and are compared with the corresponding values for the isoelectronic/isostructural R3NCH3∙CB complexes. Ammonia borane (H3NBH3) does not form a host-guest complex with CB . The trends in the host-guest stability constant with the guest molar volume are examined, and the stability is ascribed to the hydrophobic effect (packing coefficient) and quadrupole-dipole interactions.

中文翻译：

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葫芦巴[7]脲在水溶液中对胺硼烷和等电子/等结构季烷基铵阳离子的主客体络合

已使用 1 H 和 11 B NMR 光谱研究了六胺硼烷 (R3NBH3) 与水溶液中大环主体分子葫芦脲 (CB ) 的主客体络合。有限络合引起的 1H 和 11B 化学位移变化表明胺硼烷包含在主体分子的疏水腔中。中性 R3NBH3∙CB 配合物的主客体稳定性常数（在 105-107 范围内）已通过 1H NMR 竞争实验确定，并与等电子/同结构 R3NCH3∙CB 配合物的相应值进行比较。氨硼烷 (H3NBH3) 不与 CB 形成主客体复合物。检查主客体稳定性常数与客体摩尔体积的趋势，