Efficient syntheses of bis(m-phenylene)-26-crown-8-based cryptand/paraquat derivative [2]rotaxanes by immediate solvent evaporation method

A novel bis(m-phenylene)-26-crown-8-based cryptand has been synthesized. It has been used to prepare two 1:1 complexes with two paraquat derivatives with high association constants (6.5×10⁵ and 4.0×10⁵ M⁻¹) in acetone. In the solid state the cryptand forms a 2:1 threaded structure with paraquat and an interesting supramolecular poly2]pseudorotaxane threaded structure with a dihydroxyethyl-substituted paraquat derivative, respectively. It has been further used to prepare cryptand/paraquat derivative 2]rotaxanes efficiently by the immediate solvent evaporation method using easily available 3,5-dimethylphenyl groups as the stoppers.