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.