Supramolecular Assemblies Based on Intramolecular Three-Center Hydrogen Bond and their Applications

Abstract

The intramolecular three-center hydrogen bond is regarded as an efficient and reliable means to control molecular conformation, which can induce linear molecules to form specific conformations (folding, helix, expansion, zigzag, etc.). In this paper, the research progress on supramolecular assemblies based on different types of intramolecular three-center hydrogen bond is summarized in detail according to the kinds of hydrogen bonding atoms, such as O…H…O, S…H…X (X＝ N, O), N…H…X (X＝N, O), F…H…X (X＝F, O, N), and so on. More specifically, the synthesis of supramolecular assemblies is elaborated, including macrocyclic compounds, foldamers, porous helical compounds and molecular duplexes. Furthermore, their applications in promoting organic reactions, molecular recognition, transmembrane channels, molecular machines, soft materials are introduced. It is anticipated that this review can provide a useful reference for the synthesis and applications of the three-center hydrogel bond-based supramolecular assemblies. Keywords intramolecular three-center hydrogen bond; supramolecular self-assembly; structure design; conformation control; application [1] . 氢键强度适中, 具有方向 性、饱和性以及动态可逆性, 是自然界中最基本的分子 间弱相互作用力之一, 被广泛应用于超分子自组装领 域 [2] . 此外, 氢键的结合方式丰富 [3][4] . 根据组成氢键的 氢键给体和氢键受体数目之和, 可以分为两中心氢键 (1)、三中心氢键(2 和 3)以及四中心氢键(4)等(图 1). 其 中, 三中心氢键最初被称为"分叉型"(Bifurcated)氢键, 存在 2 种不同形式, 即 XHY 型(H 为氢键给体, X/Y 为氢 键受体, 2)和 HXH 型(H 为氢键给体, X 为氢键受体, 3). 后来, Maluszynska [5] 和 Taylor 等 [6] 建议将 XHY 型氢键称 作三中心氢键. 事实上, 早在 1939 年 Albrecht 等 [7] 就发 现在 α-氨基乙酸晶体中存在上述定义的氢键. 直到 20 世纪 80 年代, 因在更多小分子和生物大分子的固态结 构中发现这种氢键, 人们才逐渐接受和重视三中心氢键 概念 [8] .