Organic Cage Rotaxanes

Organic cages are a robust class of molecular hosts with a myriad of applications in materials science. Despite this, there has been a paucity of explorations into the modification of their properties via external functionalization. In this work, [n]rotaxanes featuring unoccupied organic cages as stopper components and a small 2,2'-bipyridine macrocycle were constructed using the active metal template (AMT) approach. By exploiting a scrambling methodology, it was possible to synthesize cages with a defined number of interlocked components (n = 2-4). The gas uptake, solubility, and thermal properties of the interlocked systems were compared against those of their constituent, non-interlocked components. In this manner, we were able to demonstrate the potential of exploiting the mechanical bond for modulating the physiochemical properties of these molecular materials.