title: Bis(imidazolium)-calix[4]arene receptors for anion binding.
abstract: Efficient access to the bis(imidazolyl)calixarene 2 and dicationic bis(imidazolium) salts 1a,b x 2X directly bonded to the upper rim of calixarene structure has been reported. Anion binding properties of the new receptors were studied by 1H NMR spectroscopic methods. Bis(N-butylimidazolium) dication 1a exhibited the best recognition properties toward carboxylate anions with a 1:1 receptor-anion binding stoichiometry, whereas the presence of a bulky group such as isopropyl (1b) increased the difficulty of both imidazolium moieties to be able to support the association with the same single anion.
authors.affiliation: Laboratori de Química Orgànica, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028-Barcelona, Spain.
authors.forename: Immaculada
authors.initials: I
authors.lastname: Dinarès
authors.forename: Cristina
authors.initials: C
authors.lastname: Garcia de Miguel
authors.forename: Neus
authors.initials: N
authors.lastname: Mesquida
authors.forename: Ermitas
authors.initials: E
authors.lastname: Alcalde
mesh_terms: D000838:Anions / Q000737:chemistry; D001665:Binding Sites; D047250:Calixarenes / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D007093:Imidazoles / Q000138:chemical synthesis / Q000737:chemistry*; D007454:Iodides / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D010636:Phenols / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D000838:Anions; D007093:Imidazoles; D007454:Iodides; D010636:Phenols; C121325:calix(4)arene; D047250:Calixarenes; D003300:Copper; C073870:cuprous iodide