School of Chemistry, The Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel.
Chemistry. 2012 Jul 2;18(27):8515-20. doi: 10.1002/chem.201102809. Epub 2012 May 25.
After more than a century of research on resorcin[4]arenes (1) it is clear that such systems form spontaneously [1(6)(H(2)O)(8)]-type hexameric capsules in wet, non-polar, organic solvents. However, the interactions of these hexameric capsules with alcohols are far from being solved. Here we provide the results of an extensive study on the interaction of different alcohols with the hexameric capsules of resorcin[4]arene 1a by focusing on the exchange of magnetization manifested in diffusion NMR measurements of such capsular systems. We found that some alcohols such as 2-octyl-1-dodecanol and 1-octadecanol do not interact with the hexamers of 1a, whereas other alcohols such as 3-ethyl-3-pentanol, 2-ethyl-1-butanol and more act as simple guests and are simply encapsulated in the hexamers. Others alcohols such as 3-pentanol, 2-methyl-1-butanol and others, are part of the hexameric structure where they can exchange magnetization with alcohols in the bulk. The bulkier alcohols, due to an increase of the chain length or in branching, have a higher tendency to be encapsulated rather than being part of the hexameric capsule superstructure. This study demonstrate the unique information that diffusion NMR spectroscopy can provide on supramolecular systems in solution and on the precaution that should be exercised when analyzing diffusion NMR data of such dynamic supramolecular capsules.
经过一个多世纪对间苯二酚[4]芳烃（1）的研究，很明显，在潮湿的非极性有机溶剂中，此类系统会自发形成[1(6)(H(2)O)(8)]型六聚体胶囊。然而，这些六聚体胶囊与醇的相互作用还远未解决。在这里，我们通过聚焦于磁化交换的扩散 NMR 测量，提供了对不同醇与间苯二酚[4]芳烃 1a 的六聚体胶囊相互作用的广泛研究结果。我们发现，一些醇，如 2-辛基-1-十二醇和 1-十八醇，与 1a 的六聚体不相互作用，而其他醇，如 3-乙基-3-戊醇、2-乙基-1-丁醇和更多的醇，作为简单的客体被简单地包裹在六聚体中。其他醇，如 3-戊醇、2-甲基-1-丁醇和其他醇，是六聚体结构的一部分，它们可以与体相中的醇进行磁化交换。由于链长增加或支化，较大的醇更倾向于被包裹，而不是成为六聚体胶囊超结构的一部分。这项研究证明了扩散 NMR 光谱在溶液中对超分子体系以及在分析此类动态超分子胶囊的扩散 NMR 数据时应谨慎的独特信息。
