Preorganizing Linear (Self-Complementary) Quadruple Hydrogen-Bonding Arrays Using Intramolecular Hydrogen Bonding as the Sole Force

In this article we describe a rational approach for prefixing multiple cooperative binding sites in
an ideal spatial arrangement on a structurally rigid backbone, constrained exclusively by
intramolecular hydrogen bonding. The idea is exemplified by the ability of the self-assembling
constructs 1a−e and 2a,b to form hydrogen-bonded dimers, whose structural preorganization has
been solely effected by intramolecular hydrogen bonding. The readily accessible amidinourea
backbone has been used as a common platform for the construction of a variety of such
self-assembling systems. ESI mass spectrometry and single-crystal X-ray diffraction studies have
been particularly effective in investigating the self-assembling propensities of these systems.
Remarkably, most the H-bonded dimers reported herein undergo an unusual mode of self-assembly,
using intermolecular four-membered ring hydrogen-bonded interaction, affording extended supramolecular networks.

本文报道了一种理性策略，可在结构刚性骨架上以理想空间排布预设多个协同结合位点，且该排布仅受分子内氢键（intramolecular hydrogen bonding）约束。该策略可通过自组装结构1a-e与2a,b形成氢键二聚体的能力得以验证，这类二聚体的结构预组织过程完全由分子内氢键驱动。易于获取的脒基脲（amidinourea）骨架被用作构建各类此类自组装体系的通用平台。电喷雾电离质谱（ESI mass spectrometry）与单晶X射线衍射（single-crystal X-ray diffraction）技术在研究这些体系的自组装倾向方面成效显著。值得注意的是，本文报道的多数氢键二聚体以一种非常规的自组装模式进行组装，借助分子间四元环氢键相互作用形成了延展型超分子网络。