Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
J Am Chem Soc. 2022 Mar 30;144(12):5350-5358. doi: 10.1021/jacs.1c11793. Epub 2022 Mar 11.
Spatial sequestration of molecules is a prerequisite for the complexity of biological systems, enabling the occurrence of numerous, often non-compatible chemical reactions and processes in one cell at the same time. Inspired by this compartmentalization concept, chemists design and synthesize artificial nanocontainers (capsules and cages) and use them to mimic the biological complexity and for new applications in recognition, separation, and catalysis. Here, we report the formation of large closed-shell species by interactions of well-known polyphenolic macrocycles with anions. It has been known since many years that C-alkyl resorcin[4]arenes () and C-alkyl pyrogallol[4]arenes () narcissistically self-assemble in nonpolar solvents to form hydrogen-bonded capsules. Here, we show a new interaction model that additionally involves anions as interacting partners and leads to even larger capsular species. Diffusion-ordered spectroscopy and titration experiments indicate that the anion-sealed species have a diameter of >26 Å and suggest stoichiometry ()(X) and tight ion pairing with cations. This self-assembly is effective in a nonpolar environment (THF and benzene but not in chloroform), however, requires initiation by mechanochemistry (dry milling) in the case of non-compatible solubility. Notably, it is common among various polyphenolic macrocycles () having diverse geometries and various conformational lability.
分子的空间隔离是生物系统复杂性的前提，使许多通常不兼容的化学反应和过程能够在一个细胞中同时发生。受这种分隔概念的启发，化学家设计和合成了人工纳米容器（胶囊和笼），并将其用于模拟生物复杂性，并在识别、分离和催化方面有新的应用。在这里，我们报告了通过众所周知的多酚大环与阴离子的相互作用形成大的闭壳物种。多年来，人们已经知道 C-烷基间苯二酚[4]芳烃（）和 C-烷基连苯三酚[4]芳烃（）在非极性溶剂中会自恋地自组装形成氢键胶囊。在这里，我们展示了一个新的相互作用模型，该模型还涉及阴离子作为相互作用的伙伴，并导致更大的胶囊物种。扩散有序光谱和滴定实验表明，阴离子密封的物种的直径>26 Å，并表明与阳离子具有化学计量比（）（X）和紧密的离子配对。这种自组装在非极性环境（THF 和苯中）中是有效的，但在不兼容的溶解度的情况下需要通过机械化学（干法研磨）来引发。值得注意的是，它在具有不同几何形状和各种构象不稳定性的各种多酚大环（）中很常见。
