Self-Sorting Molecular Clips

We report the synthesis and characterization of 12 C-shaped methylene-bridged glycoluril dimers (1−12) bearing H-bonding groups on their aromatic rings. Compounds 1, 2, (±)-4a, (±)-5, (±)-7, and 8 form tightly associated homodimers in CDCl3, due to the combined driving force of π−π and H-bonding interactions. Compounds 2, (±)-5, and 8, having disparate spatial distribution of their H-bonding groups, display the ability to efficiently distinguish between self and nonself even within three-component mixtures in CDCl3. When the spatial distributions of the H-bonding groups of the molecular clips are similar (e.g., 1 and 2), a mixture of homodimers and heterodimers is formed. The effect of various structural modifications (e.g., chirality, side chain steric bulk, number and pattern of H-bonds) on the strength of self-assembly and the fidelity of self-sorting are presented. On the basis of these results we prepared self-sorting systems comprising three (e.g., 1, (±)-5, and (±)-7) and even four (2, (±)-5, 9, and 10) components. The potential of molecular clips 1−12 as robust, functionalizable, self-sorting modules to control the noncovalent interaction network in systems chemistry studies is described.

本研究报道了12种在芳香环上带有氢键基团（hydrogen-bonding groups）的C形亚甲基桥联甘脲二聚体（化合物1−12）的合成与表征。在氘代氯仿（CDCl3）中，化合物1、2、(±)-4a、(±)-5、(±)-7与8会形成紧密结合的同二聚体（homodimers），该过程由π-π相互作用与氢键相互作用共同驱动。化合物2、(±)-5与8的氢键基团空间分布不均，即便在氘代氯仿的三组分混合体系中，仍能高效区分自与非自。当此类分子夹（molecular clips）的氢键基团空间分布相似时（例如化合物1与2），则会形成同二聚体与异二聚体（heterodimers）的混合体系。本文考察了各类结构修饰（如手性、侧链空间位阻、氢键的数量与模式）对自组装强度与自分选（self-sorting）保真度的影响。基于上述研究结果，我们构建了包含三种组分（例如化合物1、(±)-5与(±)-7）乃至四种组分（2、(±)-5、9与10）的自分选体系。本文还阐述了分子夹1−12作为稳定、可功能化且具备自分选能力的模块，用于调控系统化学（systems chemistry）研究中非共价相互作用网络的应用潜力。