Cyclobis(paraquat-p-phenylene) (formally a derivative of paraquat) is a molecule that belongs to the class of cyclophanes, and consists of aromatic units connected by methylene bridges.

[4] The charge-transfer interactions, present in complexes of cyclobis(paraquat-p-phenylene), can be compared as structural motif with the more commonly used hydrogen bonds, especially in terms of directionality and complementarity (lock-and-key model).

Charge-transfer complexes are easier to detect by spectroscopic methods and have a greater tolerance to various solvents, but also generally a lower association constant.

Other non-covalent bonds such as solvophobic forces, metal-ligand interaction can be used to increase the association constant; numerous structures based on this strategy are known in literature.

[8] Numerous derivatives of cyclobis(paraquat-p-phenylene) have been developed, including an enlarged version of the molecule, in the literature referred ExnBox4+, where n is the number of p-phenylene rings (n = 0-3).

Based on the charge-transfer complexation of CBPQT4 + many supramolecular structures have been created, including fibrillar gels, micelles, vesicles, nanotubes, foldamers and liquid crystalline phases.