A cycloparaphenylene can be thought of as the shortest possible cross section of an armchair carbon nanotube. Although envisioned decades ago, these molecules — also referred to as carbon nanohoops — can be highly strained and, thus, eluded chemical synthesis. However, the past decade has seen the development of methods to access carbon nanohoops of varying size and composition. In contrast to many carbon-rich materials, the nanohoops are atom-precise and structurally tunable because they are prepared by stepwise organic synthesis. Accordingly, a variety of unique, size-dependent optoelectronic and host–guest properties have been uncovered. In this Review, we highlight recent research that aims to leverage the unique physical properties of nanohoops in applications and emphasize the connection between structure and properties.

可以将环对亚苯基视为扶手椅碳纳米管的最短横截面。尽管几十年前就已设想到了，但这些分子（也称为碳纳米环）可能受到高度拉伤，因此无法进行化学合成。然而，在过去的十年中，已经出现了访问具有不同大小和组成的碳纳米环的方法的方法。与许多富含碳的材料相比，纳米环是原子精确的并且在结构上可调谐，因为它们是通过逐步有机合成制备的。因此，已经发现了各种独特的，与尺寸有关的光电特性和主客体特性。在这篇综述中，我们重点介绍了旨在利用纳米环在应用中的独特物理特性并强调结构与特性之间的联系的最新研究。