Improved and Controlled Complexation of Paraquat Derivatives by the Formation of a Bis( m ‐phenylene)‐26‐Crown‐8‐Based Lariat Ether

A novel bis( m ‐phenylene)‐26‐crown‐8‐based lariat ether (i.e., 3b ) was synthesized and characterized. It can bind paraquat derivatives more strongly than bis( m ‐phenylene)‐26‐crown‐8 in solution. It forms pseudorotaxanes with two paraquat derivatives in the solid state. N ‐Methyl substitution was found to play an important role on the binding strength of lariat ether 3b . Furthermore, due to the introduction of two benzyloxy groups, its binding to paraquat derivatives can be switched off (and back on) by adding K + (and then dibenzo‐18‐crown‐6), and the disassociation percentage depends on the concentration of the added K + ions.