Butylated pillar[5]arene (1) and N,N′-bis(n-butyl)pyromellitic diimide (2) form a 2 : 1 sandwich-type complex external to the walls of the receptor (“exo-wall” complex). The marriage of exo-wall interactions and endo-cavity inclusion provides a new strategy for the construction of supramolecular polymers from unfunctionalized neutral receptors.