The solid state and solution structures of the 1 : 1 complex formed between the cyclobis(paraquat-p-phenylene) tetracationic cyclophane and 1,5-dimethoxynaphthalene has led to the successful design and characterisation by X-ray crystallography of a prototype for the construction of a molecular abacus in the shape of a 2 : 1 complex between the same cyclophane and 1,3-bis(5-hydroxy-1-naphthyloxy) propane.