Rotaxanes Based on the 1,2‐Bis(pyridinio)ethane–24‐Crown‐8 Templating Motif

Abstract

Abstract The supramolecular interaction between 1,2‐bis(pyridinio)ethane axles and 24‐membered crown ether wheels provides a template for the formation of interpenetrated [2]pseudorotaxanes. The preformed [2]pseudorotaxanes can then be kinetically trapped to produce permanently interlocked [2]rotaxanes by stoppering with bulky groups that prevent the unthreading of the resulting dumbbell from the wheel. Six [2]rotaxanes were created using 24‐crown‐8 ( 24C8 ), dibenzo‐24‐crown‐8 ( DB24C8 ) and dinaphtho‐24‐crown‐8 ( DN24C8 ) as the wheel and two methods of stoppering; alkylation of a terminal pyridine with tert ‐butylbenzyl groups and esterification of a terminal benzyl alcohol with p ‐( tert ‐butyl)benzoate groups. The [2]rotaxanes were characterized by 1 H NMR spectroscopy, electro‐spray mass spectrometry and X‐ray crystallography.