Polyynes are chains of sp¹ carbon atoms with alternating single and triple bonds. As they become longer, they evolve towards carbyne, the 1D allotrope of carbon, and they become increasingly unstable. It has been anticipated that long polyynes could be stabilized by supramolecular encapsulation, by threading them through macrocycles to form polyrotaxanes—but, until now, polyyne polyrotaxanes with many threaded macrocycles have been synthetically inaccessible. Here we show that masked alkynes, in which the C≡C triple bond is temporarily coordinated to cobalt, can be used to synthesize polyrotaxanes, up to the C₆₈ [5]rotaxane with 34 contiguous triple bonds and four threaded macrocycles. This is the length regime at which the electronic properties of polyynes converge to those of carbyne. Cyclocarbons constitute a related family of molecular carbon allotropes, and cobalt-masked alkynes also provide a route to [3]catenanes and [5]catenanes built around cobalt complexes of cyclo[40]carbon and cyclo[80]carbon, respectively.

多炔是具有交替单键和三键的sp ¹碳原子链。随着它们变得更长，它们会演化为碳炔（碳的一维同素异形体），并且变得越来越不稳定。人们预计长多炔可以通过超分子封装来稳定，通过将它们穿过大环形成聚轮烷，但是到目前为止，具有许多螺纹大环的多炔聚轮烷在合成上是无法获得的。在这里，我们证明了掩蔽炔烃（其中C=C三键暂时与钴配位）可用于合成聚轮烷，直至具有34个连续三键和四个螺纹大环的C ₆₈ [5]轮烷。这是多炔的电子性质收敛于碳炔的电子性质的长度范围。环碳构成分子碳同素异形体的相关家族，钴掩蔽的炔烃也提供了分别围绕环[40]碳和环[80]碳的钴配合物构建的[3]环烷和[5]环烷的路线。