A pair of triptycene-derived oxacalixarenes, 1 a and 1 b, containing two naphthyridine subunits have been synthesized by a convenient one-pot approach. Macrocycles 1 a and 1 b are diastereomers, with 1 a being a cis isomer with a boat-like 1,3-alternate conformation and 1 b being a trans isomer with a curved boat-like conformation in the solid state. Both 1 a and 1 b have fixed conformations in solution at room temperature, as revealed by variable-temperature 1H NMR spectroscopy experiments. It was found that oxacalixarenes 1 a and 1 b could both form 1:1 pseudorotaxane-type complexes with paraquat derivatives with different functional groups in solution and in the solid state, which resulted in the further synthesis of a pair of novel isomeric rotaxanes. Moreover, the controlled dethreading and rethreading processes of the pseudorotaxanes were also easily achieved by acid–base stimuli or Hg2+ association/dissociation.
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