上海大学于洋团队报道了水中刚性空腔主体中的弯曲客体、形状选择性和封装。相关研究成果发表在2021年11月11日出版的国际学术期刊《美国化学会杂志》。

研究人员报道了两种具有刚性开口端的水溶性容器化合物（cavitand主体）的合成和表征。一个空腔使用四个(CH2)4作为间隔物桥接相邻墙壁，而另一个空腔使用四个CH2CH2OCH2CH2桥接，具有更宽的开口端。间隔物将深空腔预先组织成花瓶状、可接受的形状，并阻止它们向不可接受的风筝状构象展开。环烷烃客体（C6–C8）和小正构烷烃（C5–C7）与空腔形成1:1的配合物，并在空腔空间中自由移动。

亲水性化合物1,4-二氧六环、四氢呋喃、四氢吡喃、吡啶和1-甲基咪唑也显示出与新的空穴烷具有良好的结合亲和力。较长的烷烃（C11–C14）和正构醇（C11–C16）被固定在空腔底部的CH3基团和边缘附近的压缩构象基团占据。亚甲基桥似乎将空腔分隔为一个狭窄的疏水隔室和一个暴露于水介质的更宽空间。较长的烷烃客体（C15–C18）、N，N-二甲基二辛胺和二辛胺诱导形成胶囊（2:1主体：客体复合物）。

新的空腔对间甲酚异构体和二甲苯异构体具有选择性。带有CH2CH2OCH2CH2桥的空腔与长链α，ω-二醇（C13–C15）和二胺以折叠的具有极性功能的U形构象暴露于水介质中。通过使用简单的萃取方法将邻二甲苯与其异构体分离。

附：英文原文

Title: Rigidified Cavitand Hosts in Water: Bent Guests, Shape Selectivity, and Encapsulation

Author: Ji-Min Yang, Yong-Qing Chen, Yang Yu, Pablo Ballester, Julius Rebek, Jr.

Issue&Volume: November 11, 2021

Abstract: We report the synthesis and characterization of two water-soluble container compounds (cavitand hosts) with rigidified open ends. One cavitand uses four (CH2)4’s as spacers to bridge the adjacent walls, while another cavitand uses four CH2CH2OCH2CH2’s bridges and features a wider open end. The spacers preorganize the deep cavitands into vase-like, receptive shapes and prevent their unfolding to the unreceptive kite-like conformation. Cycloalkane guests (C6–C8) and small n-alkanes (C5–C7) form 1:1 complexes with the cavitands and move freely in the cavitands’ spaces. Hydrophilic compounds 1,4-dioxane, tetrahydrofuran, tetrahydropyran, pyridine, and 1-methylimidazole also showed good binding affinity to the new cavitands. Longer alkanes (C11–C14) and n-alcohols (C11–C16) are taken up with a CH3 group fixed at the bottom of the cavity and the groups near the rim in compressed conformations. The methylene bridges appear to divide the cavitand into a narrow hydrophobic compartment and a broader space with exposure to the aqueous medium. Longer alkane guests (C15–C18), N,N-dimethyldioctylammonium, and dioctylamine induce the formation of capsules (2:1 host:guest complexes). The new cavitands showed selectivity for p/m-cresol isomers and xylene isomers. The cavitand with CH2CH2OCH2CH2 bridges bound long-chain α,ω-diols (C13–C15) and diamines in folded, U-shaped conformations with polar functions exposed to the aqueous medium. It was used to separate o-xylene from its isomers by using simple extraction procedures.

DOI: 10.1021/jacs.1c09226

Source: https://pubs.acs.org/doi/10.1021/jacs.1c09226