Multiply stranded and multiply encircled pseudorotaxanes

Abstract

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 are 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 1H NMR spectroscopy, X-ray crystallography, and mass spectrometry, respectively.