Tetrabenzo[8]circulene: Aromatic Saddles from Negatively Curved Graphene

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• 作者：Youichi Sakamoto ; Toshiyasu Suzuki
• 刊名：Journal of the American Chemical Society
• 出版年：2013
• 出版时间：September 25, 2013
• 年：2013
• 卷：135
• 期：38
• 页码：14074-14077
• 全文大小：380K
• 年卷期：v.135,no.38(September 25, 2013)
• ISSN：1520-5126

文摘

An aromatic saddle was designed from the hypothetical three-dimensional graphene with the negative Gaussian curvature (Schwarzite P192). Two aromatic saddles, tetrabenzo[8]circulene (TB8C) and its octamethyl derivative OM-TB8C, were synthesized by the Scholl reaction of cyclic octaphenylene precursors. The structure of TB8C greatly deviates from planarity, and the deep saddle shape was confirmed by single-crystal X-ray crystallography. There are two conformers with the S₄ symmetry, which are twisted compared to the DFT structure (D_2d). The theoretical studies propose that the interconversion of TB8C via the planar transition state (125 kcal mol^鈥?) is not possible. However, the pseudorotation leads to a low-energy tub-to-tub inversion via the nonplanar transition state (7.3 kcal mol^鈥?). The ground-state structure of TB8C in solution is quite different from the X-ray structure because of the crystal-packing force and low-energy pseudorotation. OM-TB8C is a good electron donor and works as the p-type semiconductor.