Molecular meccano, part 24. Multiply stranded and multiply encircled pseudorotaxanes

The self-assembly of four multicomponent rotaxane-like complexes, in which either (a) three or four dibenzo[24]crown-8 rings encircle threadlike oligoammonium cations [PhCH2(NH2+CH2C6H4CH2)(n)NH2+CH2Ph] (n = 2 or 3) to form multiply encircled pseudorotaxanes, or (b) three or four dibenzylammonium ions an threaded simultaneously through large macrocyclic polyethers, viz., tris-p-phenylene[51]crown-15 and tetrakis-p-phenylene[68]crown-20, to give multiply stranded pseudorotaxanes, is described. These supramolecular entities are created on account of stabilizing [N+-H ... O] and [C-H ... O] hydrogen bonds, supplemented occasionally by aromatic face-to-face and edge-to-face interactions, and [C-H ... F] intermolecular bonds. Evidence for the existence of these diverse pseudorotaxane architectures in solution, in the solid state, and in some cases, in the "gas phase", is provided by H-1 MMR spectroscopy, X-ray crystallography, and mass spectrometry, respectively.