Cyclacene nanobelts have not been synthesized in over 60 years and remain one of the last unsynthesized building blocks of carbon nanotubes. Recent work has predicted that Hückel-cyclacenes containing Dewar benzenoid ring isomers are the most stable isomeric forms for several of the smaller sizes of cyclacene belts. Here, we give a more complete picture of the isomers that are possible within these nanobelt systems by simulating embedded Ladenburg (prismane) benzenoid rings in Hückel-[n]cyclacenes (n = 5–14) and embedded Dewar benzenoid rings in twisted Möbius-[n]cyclacenes (n = 9–14). The Möbius-[9]cyclacene isomer containing one Dewar benzenoid defect and the Hückel-[5]cyclacene isomer containing two maximally spaced Ladenburg benzenoid defects are found to be more stable than their conventional Kekulé benzenoid ring counterparts. The isomers that contain Dewar and Ladenburg benzenoid rings have larger electronic singlet–triplet energy gaps and lower polyradical character when compared with the conventional isomers.

中文翻译：

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Möbius和HückelCyclacenes与Dewar和Ladenburg缺陷。

并六苯纳米带已经超过60年没有合成，并且仍然是碳纳米管中最后未合成的构建基块之一。最近的工作预测，对于一些较小尺寸的并四苯环带，含有杜瓦苯环类异构体的Hückel-Cyclacenes是最稳定的异构形式。在这里，我们通过模拟Hückel-[ n ]环并苯环（n = 5-14）中的嵌入Ladenburg（ism烷）苯环和n扭曲的Möbius-中的Dewar苯并环，来更完整地了解这些纳米带系统中可能存在的异构体。[ n ]环戊烯（n= 9-14）。发现具有一个杜瓦苯甲醛类缺陷的Möbius-[9]环并苯异构体和包含两个最大间隔的拉登堡苯类缺陷的Hückel-[5]环并苯异构体比常规的Kekulé苯并类似物环更稳定。与常规异构体相比，包含杜瓦和拉登堡苯环的异构体具有更大的电子单重态-三重态能隙，且多自由基特性较低。