[2]Pseudorotaxanes from T-shaped benzimidazolium axles and [24]crown-8 wheels.

A new templating motif for the formation of [2]pseudorotaxanes is described in which T-shaped axles with a benzimidazolium core and aromatic substituents at the 2-, 4-, and 7-positions interact with [24]crown-8 ether wheels ([24]crown-8, dibenzo[24]crown-8, and dinaphtho[24]crown-8). The T-shape greatly enhances the association between axle and wheel when compared to simple imidazolium or benzimidazolium cations. A series of interpenetrated molecules are characterized by (1)H NMR spectroscopy and single crystal X-ray crystallography.