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

Abstract

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.

Surfactant-induced chirality transfer, amplification and inversion in a cucurbit[8]uril–viologen host–guest supramolecular system

“…Viologens, 40,41 N , N ′ di-quaternized bipyridyl salts with cationic units, are well-studied species and commonly used as guest components to interact with different cucurbituril macrocycles. 42–45 Due to the reversible redox states, cationic properties, and tunability of the nitrogen substituents, viologens are used as functional groups in many systems such as molecular machines, electrochemical devices, batteries, and stimuli-responsive materials. 46–50 Zhang et al recently developed a new light-powered dissipative supramolecular polymerization approach by taking advantage of a 2 : 1 host–guest complexation of viologen moieties and CB[8] in the aqueous solution, offering a rational way to regulate different supramolecular states using light.…”

Photocharging of Materials

“…Construction of microporous COFs that possess photoredox active moieties and interconected by low-molecular weight linkers might provide a class of materials with high δ max . [132], [133], [134] Overall, microporous structure, high ionic conductivity and highly positive VB potential are three the most important parameters to reach high δ max , R PC andR DC .…”

Nanoscale covalent organic frameworks as theranostic platforms for oncotherapy: synthesis, functionalization, and applications

“…Generally, the charge is located on the monomers, such as benzimidazolium, 184 guanidinium, 185,186 and viologen. [187][188][189] As reported by Banerjee et al, 185 three COFs, namely, TpTG X (X ¼ Cl, Br, and I), were constructed based on the Schiff-base condensation reaction of triaminoguanidinium halide and 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde ( Fig. 24A).…”