catenanesinterlinked

Catenanes interlinked are a class of mechanically interlocked molecules in which two or more macrocyclic rings are linked like links in a chain. The simplest example is a [2]catenane, consisting of two interlocked rings; higher-order interlocked assemblies are referred to as [n]catenanes. Because the rings are not covalently bonded, they are held together by their topology rather than by chemical bonds, making them a subset of mechanically interlocked molecules (MIMs). Their interlocked structure prevents separation without breaking a covalent bond, yet allows relative motion of the rings.

The interlocked topology gives catenanes distinctive properties. The rings can move with respect to one another, enabling mechanisms such as molecular shuttling and switching. The motion can be controlled by external stimuli such as redox changes, pH shifts, light, or binding events, making catenanes of interest as components in nanoscale devices and responsive materials. The behavior of catenanes also provides insight into fundamental questions about topology and dynamics at the molecular level.

Synthesis of catenanes typically relies on template-directed strategies that preorganize components so that rings become interlocked during assembly. Common approaches include metal-templated synthesis, which uses coordination chemistry to hold parts in place; and clipping or threading methods followed by stoppering to lock the topology in place. Dynamic covalent chemistry and noncovalent self-assembly have also been used to construct catenanes.

Applications and research focus include molecular machines, sensors, and smart materials. Catenanes serve as model systems for studying controlled motion in nanoscale architectures and hold potential for information storage, signal transduction, and adaptive materials, while also advancing the broader understanding of mechanically interlocked architectures.