Center for Advancing Electronics Dresden & Department of Chemistry and Food Chemistry, Technische Universität Dresden , 01062 Dresden, Germany.
Laboratory for Chemistry of Novel Materials, University of Mons , B-7000 Mons, Belgium.
J Am Chem Soc. 2016 Jul 13;138(27):8364-7. doi: 10.1021/jacs.6b04426. Epub 2016 Jul 1.
Total synthetic approaches of fullerenes are the holy grail for organic chemistry. So far, the main attempts have focused on the synthesis of the buckminsterfullerene C60. In contrast, access to subunits of the homologue C70 remains challenging. Here, we demonstrate an efficient bottom-up strategy toward a novel bowl-shaped polycyclic aromatic hydrocarbons (PAH) C34 with two pentagons. This PAH represents a subunit for C70 and of other higher fullerenes. The bowl-shaped structure was unambiguously determined by X-ray crystallography. A bowl-to-bowl inversion for a C70 fragment in solution was investigated by dynamic NMR analysis, showing a bowl-to-bowl inversion energy (ΔG(⧧)) of 16.7 kcal mol(-1), which is further corroborated by DFT calculations.
全合成富勒烯的方法是有机化学的圣杯。到目前为止，主要的尝试都集中在富勒烯 C60 的合成上。相比之下，获得同系物 C70 的亚单位仍然具有挑战性。在这里，我们展示了一种有效的自下而上的策略，用于合成具有两个五元环的新型碗状多环芳烃（PAH）C34。这个 PAH 代表了 C70 和其他更高阶富勒烯的一个亚单位。通过 X 射线晶体学明确确定了碗状结构。通过动态 NMR 分析研究了溶液中 C70 片段的碗到碗反转，结果表明碗到碗反转能（ΔG(⧧)）为 16.7 kcal mol(-1)，这进一步得到了 DFT 计算的证实。
