The need for advanced energy storage technologies demands the development of new functional materials. Novel carbon-rich and carbon-based materials of different structural topologies attract significant attention in this regard. Attractive systems include a unique class of bowl-shaped polycyclic aromatic hydrocarbons that map onto fullerene surfaces and are thus often referred to as fullerene fragments, buckybowls, or π-bowls. Importantly, carbon bowls are able to acquire multiple electrons in stepwise reduction reactions producing sets of successively reduced carbanions. The resulting negatively charged π-bowls exhibit unique supramolecular assembly and metal intercalation patterns that only recently have begun to be uncovered. First, we have resolved the long-standing mystery behind the supramolecular structure formed by a highly reduced fullerene fragment called corannulene (C₂₀H₁₀^4–) with multiple lithium ions, using X-ray crystallography coupled with NMR spectroscopy and theoretical calculations. This work provided a new paradigm for lithium ion intercalation between the curved carbon π-surfaces and facilitated understanding of the lithium ion storage mechanism in carbonaceous matrices. Next, we have initiated a new research direction, an investigation of the mixed alkali metal reduction reactions using bowl-shaped corannulene as a remarkable multielectron reservoir and unique ligand with open convex and concave π-surfaces. As a result, we have revealed the cooperative effect of lithium with heavier Group 1 metals in reduction and self-assembly processes of corannulene. Moreover, we have discovered a new class of organometallic supramolecules having heterometallic cores with high nuclearity and charge such as Li₃M₃⁶⁺ and LiM₅⁶⁺ (M = K, Rb, and Cs) sandwiched between two tetrareduced corannulene decks. The resulting triple-decker supramolecular assemblies, fully characterized by X-ray diffraction and spectroscopic methods, were found to exhibit a record ability of the highly charged corannulene π-surfaces to be fully engaged in intercalation of multiple metal ions. Based on this unique ability, curved π-ligands with extended carbon frameworks are expected to show remarkable potential for alkali metal storage compared to flat polycyclic arenes. Notably, a previously unseen mode of internal lithium binding revealed in the heterobimetallic sandwiches is accompanied by unprecedented negative shifts (up to −25 ppm) in ⁷Li NMR spectra. Based on in-depth analysis of NMR data, augmented by DFT calculations, we have rationalized the observed experimental trends and proposed the mechanism of stepwise alkali metal substitution reactions. Furthermore, we have correlated the origin of the record ⁷Li NMR shifts with unique electronic structures of these novel supramolecular aggregates. Herein we present comprehensive analysis of unusual structural and electronic features of remarkable heterometallic self-assemblies formed by tetrareduced corannulene, using a wealth of our recent experimental and computational results. This work uncovers unique potential of highly negatively charged bowl-shaped π-ligands for new supramolecular chemistry and materials chemistry applications.

中文翻译：

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通过高电荷的Corannulene记录碱金属插层

对先进的储能技术的需求要求开发新的功能材料。在这方面，具有不同结构拓扑的新型富碳和基于碳的材料引起了极大的关注。吸引人的系统包括一类独特的碗形多环芳烃，它们映射在富勒烯表面，因此通常被称为富勒烯片段，buckybowls或π-bowls。重要的是，碳杯能够在逐步还原反应中获得多个电子，从而产生一系列连续还原的碳负离子。所得的带负电的π碗展现出独特的超分子组装和金属嵌入模式，直到最近才开始发现它们。第一的，₂₀小时₁₀ ^{4 –}），并使用X射线晶体学，NMR光谱学和理论计算方法。这项工作为弯曲的碳π表面之间的锂离子嵌入提供了新的范例，并有助于理解碳质基质中的锂离子存储机理。接下来，我们开始了一个新的研究方向，即使用碗形的氢化蒽环作为显着的多电子储集层和具有开放的π和π表面开放的独特配体的混合碱金属还原反应的研究。结果，我们揭示了锂与较重的1族金属在氢化萘的还原和自组装过程中的协同作用。此外，我们发现了一类新型的具有高核化和高电荷杂金属核的有机金属超分子₃ M ₃ ⁶⁺和LiM ₅ ⁶⁺（M = K，Rb和Cs）夹在两个四还原的ann环中。发现通过X射线衍射和光谱学方法完全表征的所得三层超分子组件显示出高电荷的氢化露环烯π表面完全参与多种金属离子的插入的记录能力。基于这种独特的能力，与平坦的多环芳烃相比，具有扩展碳骨架的弯曲π-配体有望显示出显着的碱金属存储潜力。值得注意的是，内部的锂预先看不见模式中的异三明治结合揭示伴随前所未有负位移在（最多-25 ppm的）⁷Li NMR谱。在对NMR数据进行深入分析的基础上，通过DFT计算的增加，我们合理化了观察到的实验趋势，并提出了逐步碱金属取代反应的机理。此外，我们已经将记录的⁷ Li NMR位移的起源与这些新型超分子聚集体的独特电子结构相关联。在本文中，我们使用大量的最新实验和计算结果，对由四还原的氢化蒽环形成的显着异金属自组装体的异常结构和电子特征进行了综合分析。这项工作发现了带负电的碗状π-配体在新的超分子化学和材料化学应用中的独特潜力。