title: Selective binding of imidazolium cations in building multi-component layers.
abstract: Addition of 1-alkyl-3-methylimidazolium (C(n)-mim) cations 3-5 to a mixture of bis-phosphonium cation 2 and sodium p-sulfonatocalix[4]arene (1) in the presence of lanthanide ions results in the selective binding of an imidazolium cation into the cavity of the calixarene. The result is a multi-layered solid material with an inherently flexible interplay of the components. Incorporating ethyl-, n-butyl- or n-hexyl-mim cations into the multi-layers results in significant perturbation of the structure, the most striking effect is the tilting of the plane of the bowl-shaped calixarene relative to the plane of the multi-layer, with tilt angles of 7.2, 28.9 and 65.5 degrees , respectively. The lanthanide ions facilitate complexation, but are not incorporated into the structures and, in all cases, the calixarene takes on a 5- charge, with one of the lower-rim phenolic groups deprotonated. ROESY NMR experiments and other (1)H NMR spectroscopy studies establish the formation of 1:1 supermolecules of C(n)-mim and calixarene, regardless of the ratio of the two components, and indicate that the supermolecules undergo rapid exchange on the NMR spectroscopy timescale.
authors.affiliation: Chemistry Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Irene
authors.initials: I
authors.lastname: Ling
authors.forename: Yatimah
authors.initials: Y
authors.lastname: Alias
authors.forename: Alexandre N
authors.initials: AN
authors.lastname: Sobolev
authors.forename: Lindsay T
authors.initials: LT
authors.lastname: Byrne
authors.forename: Colin L
authors.initials: CL
authors.lastname: Raston
mesh_terms: D047250:Calixarenes / Q000737:chemistry*; D002412:Cations / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007093:Imidazoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009943:Organophosphorus Compounds / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002412:Cations; D007093:Imidazoles; D009943:Organophosphorus Compounds; D047250:Calixarenes