ABSTRACT

The unique temperature, solvent and pH drivenvase to kite equilibrium in quinoxaline cavitands allows the reversible uptake and release of guests. However, the cavity breathing associated with this conformational switch reduces the strength of complexation. A limited number of solutions have been proposed for the cavity rigidification, using either H-bonding, metal coordination or covalent connections. Here we report the synthesis and structural characterisation of quinoxaline-based cavitand baskets, which present two distal quinoxaline walls linked together. Baskets A and B were obtained through a bridging reaction starting from an AC di-quinoxaline bridged cavitand using two different di-quinoxaline moieties. In both cases, two isomers were obtained: isomer C₂, with the linking unit crossing the cavity mouth, and isomer C_s, having the linker sideways. The isomers were identified through ¹H NMR analysis. In the case of basket A-C_s, the resolved molecular structure confirmed the C_s symmetry of the basket.

摘要

独特的温度、溶剂和 pH 值驱动花瓶 在喹喔啉空腔中 达到 风筝平衡，允许客人可逆地吸收和释放。然而，与这种构象转换相关的腔呼吸会降低复合强度。已经为腔体刚性提出了有限数量的解决方案，使用 H 键合、金属配位或共价连接。在这里，我们报告了基于喹喔啉的空腔篮的合成和结构表征，它们呈现了连接在一起的两个远端喹喔啉壁。篮子 A 和 B 是通过使用两种不同的二喹喔啉部分从 AC 二喹喔啉桥连的空腔开始的桥连反应获得的。在这两种情况下，都获得了两种异构体：异构体 C ₂，连接单元穿过腔口，异构体C _s，具有侧向的连接体。通过¹ H NMR分析鉴定异构体 。在篮子 AC _s的情况下，解析的分子结构证实 了篮子的 C _s对称性。