Synthesis of a Structure-Definite α-Cyclodextrin-Based Macromolecular [3]Rotaxane Using a Size-Complementary Method.

The challenging synthesis of an α-cyclodextrin (CD)-based macromolecular rotaxane with definite structure was fulfilled using a size-complementary method. A new peracetylated (PAc) α-CD-based size-complementary [3]rotaxane was prepared and its thermal dissociation kinetics studied. The de-slippage mechanism was found to be different from that of the native α-CD-based system. PAcα-CD-based size-complementary [3]rotaxanes were employed as initiators for a ring-opening polymerization of ϵ-caprolactone to obtain the macromolecular [3]rotaxanes. Detailed investigation of component dissociation showed the highly movable character of the wheel on the polymer main chain. A general method for controlling the movement of wheels in rotaxane frameworks, even in polymer systems, was established. This will enable the development of new supramolecular architectures and molecular machines.