Templated Synthesis of Desymmetrized [2]Catenanes with Excellent Translational Selectivity^†

Desymmetrized [2]catenanes were synthesized and shown to exhibit excellent translational selectivity. The templated synthesis takes effect
from the formation of pseudorotaxanes between π-rich crown ethers and a π-deficient pyromellitic (PmI) unit, followed by macrocyclization
around the crown ethers with the creation of a bipyridinium (BPy) unit. The crown ethers preferably encircle the BPy unit in the resulting
[2]catenanes in both solution and the solid state, as indicated by various spectroscopic analyses.