Department of Materials Science and Engineering, Faculty of Engineering, University of Fukui, Bunkyo, Fukui 910-8507, Japan.
International Research Centre for Elements Science, Institute for Chemical Research, Kyoto University, Uji 611-0011, Japan.
Org Biomol Chem. 2022 Jan 5;20(2):387-395. doi: 10.1039/d1ob01694f.
In this study we self-assembled the four-armed porphyrin hetero dimer capsule Cap4, stabilized through amidinium-carboxylate salt bridges, in CHCl and CHCl. The dimer capsule Cap4 was kinetically and thermodynamically more stable than the corresponding two-armed dimer Cap2. The number of arms strongly influenced their recognition behaviour; guests possessing small aromatic faces (, 1,3,5-trinitrobenzene) preferred residing in the cavity of the two-armed capsule Cap2, rather than in Cap4, both thermodynamically and kinetically; in contrast, large aromatic guests (, 9,10-dibromoanthracene) were encapsulated predominantly by Cap4 because of favourable entropic effects. The number of arms enabled self-sorting behaviour of the dimer formation; complexation studies using an equimolar mixture of the four porphyrin constituents of the two capsules revealed the quantitative formation of the corresponding dimers Cap2 and Cap4. Furthermore, we examined the specific molecular recognition of Cap2 and Cap4; NMR experiments of mixtures of Cap2 and Cap4 in the presence of favourable guests for Cap2 and Cap4 revealed that these guest molecules were encapsulated selectively by their preferred hosts.
在这项研究中，我们通过酰胺-羧酸盐桥自组装了四臂卟啉杂二聚体胶囊 Cap4，该胶囊在 CHCl 和 CHCl 中稳定存在。二聚体胶囊 Cap4 在动力学和热力学上比相应的二聚体 Cap2 更稳定。臂的数量强烈影响它们的识别行为; 具有小芳香面的客体（如，1,3,5-三硝基苯）优先在二聚体胶囊 Cap2 的空腔中居住，而不是在 Cap4 中，无论是热力学上还是动力学上; 相比之下，较大的芳香客体（如，9,10-二溴蒽）主要由 Cap4 包封，因为有利的熵效应。臂的数量使二聚体形成具有自分类行为; 使用两个胶囊的四个卟啉成分的等摩尔混合物进行的络合研究表明，相应的二聚体 Cap2 和 Cap4 定量形成。此外，我们研究了 Cap2 和 Cap4 的特异性分子识别; 在有利于 Cap2 和 Cap4 的客体存在下，Cap2 和 Cap4 的混合物的 NMR 实验表明，这些客体分子被其首选主体选择性地包封。
