Ammonium ion binding with pyridine-containing crown ethers

[GRAPHICS] Dipyrido[24]crown-8 (DP24C8) has been synthesized and shown to form [2]pseu dorotaxanes spontaneously with dibenzylammonium ions. These complexes, whic h have been demonstrated by H-1 NMR spectroscopy to form faster in solution than when the macrocyclic polyether is dibenzo[24]crown-8 (DB24C8), are al so stronger than their DB24C8 counterparts. One of the [2]pseudorotaxanes h as been used to construct a [2]rotaxane (see above) comprising a dumbbell-s haped component based on a dibenzylammonium ion which is encircled by a DP2 4C8 macrocycle and terminated by (triphenylphosphonium)methyl stoppers.