Slow Formation of Pseudorotaxanes in Water

The synthesis of two water-soluble oligophenylene-ethynylene (OPE)-rods with substituted iso- and terephthalate end groups is presented. Both undergo slow association with a Diederich-type cyclophane in aqueous solution. Formation of [2]pseudorotaxanes occurs with reaction half-lives of several hours. Characterization of the supermolecules by 1H-NMR spectroscopy reveals a high thermodynamic stability and kinetic inertness of the pseudorotaxanes. The phthalate precursors are functionalized with peripheral azide groups, which make them modular precursors for construction of mechanically interlocked molecules in water.