A polyrotaxanated covalent organic network based on viologen and cucurbit[7]uril

Since their initial presentation in 2005 by Yaghi and co-workers, covalent organic frameworks (COFs) have been the focus of much development. Here we introduce mechanical bonds into COFs by employing a method that involves supramolecular self-assembly, dynamic imine-bond formation, and liquid-liquid interfacial condensation and produces a continuous 2D polyrotaxaneted film. A diamino-viologen linker is complexed with the macrocycle cucurbit[7]uril (CB[7]) to form pseudorotaxanes that then condense with an aromatic tri-aldehyde core at the interface of two solvents. The unrotaxanated COF is prepared by condensing the viologen and the trialdehyde in the absence of CB[7], and the chemical and physical properties of the formed films are compared. The CB[7]-encapsulated film is mechanically and thermally more robust and more luminescent. The synthetic strategy presented here allows the incorporation of mechanically interlocked molecules (MIMs) into polymeric materials and provides access to materials that have properties and functionalities that are yet to be explored.