Despite a growing understanding of factors that drive monomer self-assembly to form supramolecular polymers, the effects of aromaticity gain have been largely ignored. Herein, we document the aromaticity gain in two different self-assembly modes of squaramide-based bolaamphiphiles. Importantly, O → S substitution in squaramide synthons resulted in supramolecular polymers with increased fiber flexibility and lower degrees of polymerization. Computations and spectroscopic experiments suggest that the oxo- and thiosquaramide bolaamphiphiles self-assemble into “head-to-tail” versus “stacked” arrangements, respectively. Computed energetic and magnetic criteria of aromaticity reveal that both modes of self-assembly increase the aromatic character of the squaramide synthons, giving rise to stronger intermolecular interactions in the resultant supramolecular polymer structures. These examples suggest that both hydrogen-bonding and stacking interactions can result in increased aromaticity upon self-assembly, highlighting its relevance in monomer design.

中文翻译：

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基于硫代方酰胺的超分子聚合物：自组装切换模式下的芳香性增益

尽管对驱动单体自组装形成超分子聚合物的因素有了越来越多的了解，但芳香度增加的影响在很大程度上被忽略了。在此，我们记录了基于方酸酰胺的 bolaamphiphiles 的两种不同自组装模式中的芳香性增益。重要的是，方酸酰胺合成子中的 O → S 取代导致超分子聚合物具有增加的纤维柔韧性和较低的聚合度。计算和光谱实验表明，氧代和硫代方酰胺双亲分子分别自组装成“头对尾”和“堆叠”排列。计算出的芳香性的能量和磁性标准表明，两种自组装模式都增加了方酸酰胺合成子的芳香特性，在所得的超分子聚合物结构中产生更强的分子间相互作用。这些例子表明，氢键和堆积相互作用都可以导致自组装时增加芳香性，突出其在单体设计中的相关性。