Sun Zhe, Suenaga Takuya, Sarkar Parantap, Sato Sota, Kotani Motoko, Isobe Hiroyuki
Isobe Degenerate π-Integration Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency, Aoba-ku, Sendai 980-8577, Japan; Advanced Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan;
Advanced Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan;
Proc Natl Acad Sci U S A. 2016 Jul 19;113(29):8109-14. doi: 10.1073/pnas.1606530113. Epub 2016 Jun 29.
The chemistry of a belt-shaped cyclic array of aromatic panels, a so-called "nanohoop," has increasingly attracted much interest, partly because it serves as a segmental model of single-wall carbon nanotubes with curved sp(2)-carbon networks. Although the unique molecular structure of nanohoops is expected to deepen our understanding in curved π-systems, its structural chemistry is still in its infancy despite structural variants rapidly accumulated over the past several years. For instance, structural characteristics that endow the belt shapes with rigidity, an important structural feature relevant to carbon nanotubes, have not been clarified to date. We herein report the synthesis and structures of a series of belt-shaped cyclonaphthylenes. Random synthesis methods using three precursor units with different numbers of naphthylene panels allowed us to prepare 6 congeners consisting of 6 to 11 naphthylene panels, and relationships between the rigidity and the panel numbers, i.e., molecular structures, were investigated. Fundamental yet complicated stereoisomerism in the belt-shaped structures was disclosed by mathematical methods, and dynamics in the panel rotation was revealed by dynamic NMR studies with the aid of theoretical calculations.
一种由芳香族面板组成的带状环状阵列（即所谓的“纳米箍”）的化学性质越来越受到人们的关注，部分原因是它可作为具有弯曲sp(2) - 碳网络的单壁碳纳米管的片段模型。尽管纳米箍独特的分子结构有望加深我们对弯曲π - 体系的理解，但尽管在过去几年中结构变体迅速积累，其结构化学仍处于起步阶段。例如，赋予带状形状刚性的结构特征（这是与碳纳米管相关的重要结构特征）至今尚未阐明。我们在此报告了一系列带状环萘的合成与结构。使用具有不同数量萘面板的三种前体单元的随机合成方法使我们能够制备由6至11个萘面板组成的6种同系物，并研究了刚性与面板数量之间的关系，即分子结构。通过数学方法揭示了带状结构中基本但复杂的立体异构现象，并借助理论计算通过动态核磁共振研究揭示了面板旋转的动力学。
