University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, USA.
Science. 2011 Aug 19;333(6045):1008-11. doi: 10.1126/science.1208686.
Lithium-coordinated polyaromatic anions such as tetrareduced corannulene, C(20)H(10)(4-) (1(4-)), are useful substrates to model and ultimately improve the graphitic electrodes in lithium-ion (Li(+)) batteries. Previous studies suggested that 1(4-) forms dimers encasing four Li(+) ions in solution. Here, we report a single-crystal x-ray diffraction analysis confirming the formation of a sandwich-type supramolecular aggregate with a high degree of alkali metal intercalation. In contrast to the prior model, our data reveal that five Li(+) ions are sandwiched between the two tetrareduced corannulene decks, and (7)Li nuclear magnetic resonance spectroscopy delineates a conserved structure in tetrahydrofuran solution. Remarkably, the sandwich is robust in both solution and solid states even in the presence of crown ethers that compete for Li(+) coordination. These results should help elucidate Li(+) intercalation motifs between curved carbon surfaces more broadly.
锂配位的多环芳香阴离子，如四还原的corannulene，C(20)H(10)(4-) (1(4-))，是有用的模型底物，可用于模拟并最终改进锂离子（Li(+))电池中的石墨电极。先前的研究表明，1(4-)在溶液中形成包裹四个 Li(+)离子的二聚体。在这里，我们报告了一个单晶 X 射线衍射分析，证实了具有高程度碱金属插层的夹心型超分子聚集体的形成。与先前的模型相反，我们的数据表明，五个 Li(+)离子夹在两个四还原的 corannulene 层之间，（7)Li 核磁共振波谱描绘了四氢呋喃溶液中结构的一致性。值得注意的是，夹心结构在溶液和固态中都很稳定，即使存在竞争 Li(+)配位的冠醚也是如此。这些结果应该有助于更广泛地阐明弯曲碳表面之间的 Li(+)嵌入模式。
