Infinitene: A Helically Twisted Figure-Eight [12]Circulene Topoisomer.
Infinitene: A Helically Twisted Figure-Eight [12]Circulene Topoisomer.
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DOI：
10.33774/chemrxiv-2021-pcwcc
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发表时间：
2021-10
影响因子：
15
通讯作者：
Maciej Krzeszewski;Hideto Ito;K. Itami
中科院分区：
文献类型：
--
作者：
Maciej Krzeszewski;Hideto Ito;K. Itami
分子纳米碳的新形式，特别是采用各种拓扑结构的环状聚芳烃，为基础科学和实际应用做出了贡献。本文报道了一种无限形状的聚芳烃Infinitene(1)(cyclo[c.c.c.c.c.c.e.e.e.e.e.e]dodecakisbenzene)，的合成，它由连续稠合的12个苯环组成一个闭合环，应变能为60.2kcal·mol-1。Infinitene(1)代表一种仍然假设的[12]环烯的拓扑异构体，它的支架可以形式化地可视化为两个高手性[6]螺烯亚基两端“缝合”的结果。该合成策略包括通过相应的S，S的双(氧化物)的Stevens重排和裂解，然后光环化，将设计合理的二硫杂环番转化为环己二烯。1的结构是一种独特的螺烯和环烯杂合物，分子式为C48H24，它可以被认为是kekulene、[6，6]碳纳米带([6，6]CNB)和[12]环烯的异构体。Infinitene(1)是一种稳定的黄色固体，具有绿色荧光，可溶于普通有机溶剂。X-射线结晶学确证了其八字形分子结构。1的支架被显著压缩，表现为两个π-π堆叠的中心苯环的质心之间的距离显著缩短(3.152-3.192？)，最接近的C？···C距离为2.920？通过紫外-可见吸收光谱、荧光光谱和密度泛函理论计算，对化合物1的基本光物理性质进行了全面的研究。其构型稳定性使手性高效液相色谱分离相应的对映体(P，P)和(M，M)成为可能。圆二色谱(CD)和圆偏振发光(CPL)测量表明，1具有中等的|gCD|和|gCPL|值。
New forms of molecular nanocarbon particularly looped polyarenes adopting various topologies contribute to the fundamental science and practical applications. Here we report the synthesis of an infinity-shaped polyarene, infinitene (1) (cyclo[c.c.c.c.c.c.e.e.e.e.e.e]dodecakisbenzene), comprising consecutively fused 12-benzene rings forming an enclosed loop with a strain energy of 60.2 kcal·mol-1. Infinitene (1) represents a topoisomer of still-hypothetical [12]circulene, and its scaffold can be formally visualized as the outcome of the "stitching" of two homochiral [6]helicene subunits by both their ends. The synthetic strategy encompasses transformation of a rationally designed dithiacyclophane to cyclophadiene through the Stevens rearrangement and pyrolysis of the corresponding S,S'-bis(oxide) followed by the photocyclization. The structure of 1 is a unique hybrid of helicene and circulene with a molecular formula of C48H24, which can be regarded as an isomer for kekulene, [6,6]carbon nanobelt ([6,6]CNB), and [12]cyclacene. Infinitene (1) is a bench-stable yellow solid with green fluorescence and soluble to common organic solvents. Its figure-eight molecular structure was unambiguously confirmed by X-ray crystallography. The scaffold of 1 is significantly compressed as manifested by a remarkably shortened distance (3.152-3.192 Å) between the centroids of two π-π stacked central benzene rings and the closest C···C distance of 2.920 Å. Fundamental photophysical properties of 1 were thoroughly elucidated by UV-vis absorption and fluorescence spectroscopic studies and density functional theory calculations. Its configurational stability enabled separation of the corresponding enantiomers (P,P) and (M,M) by a chiral HPLC. Circular dichroism (CD) and circularly polarized luminescence (CPL) measurements revealed that 1 has moderate |gCD| and |gCPL| values.