Stimuli-Responsive Catenane-Branched Dendrimers with Tunable Dimension for Reversible Guest Binding

To tackle the challenge of the precise construction of catenane-based mechanically interlocked macromolecules with well-defined topological arrangements, starting from a novel [2]catenane building block with dendrimer growth sites, catenane-branched dendrimers have been precisely constructed via an efficient and controllable divergent approach. Notably, to the best of our knowledge, the third-generation dendrimer which consists of twenty-one [2]catenane branches is the most complicated discrete [2]catenane oligomer synthesized to date. Interestingly, the switchable coconformation transformations of [2]catenane branches triggered by sodium ions and cryptands lead to an integrated and amplified expansion–contraction motion of the resultant dendrimers, achieving reversible size regulation at the nanoscale. The unique recognition sites of the resultant catenane-branched dendrimers also facilitate the reversible binding of drug and dye guests. This work not only addresses the synthetic challenge of highly branched catenane dendrimers but also provides a new platform for dynamic supramolecular functional materials.