because of their versatile noncovalent interactions with various functional groups. Particularly, \pi - \pi , CH-\pi and \pi -cation interactions are widely used in supramolecular assembly and recognition.

\pi-\pi concerns the direct interactions between two -systems; and cation-\pi interaction arises from the electrostatic interaction of a cation with the face of the -system. Unlike these two interactions, the CH-\pi