title: (Thio)ureido anion receptors based on a 1,3-alternate oxacalix[2]arene[2]pyrimidine scaffold.
abstract: In pursuit of highly preorganized macrocyclic host molecules for the complexation of anions, a series of oxacalix[2]arene[2]pyrimidine-based bis(thio)ureido receptors were synthesized and fully characterized. The pincer-like 1,3-alternate conformation of the oxacalix[4]arene scaffold, essential for an efficient host-guest interaction, was visualized by single-crystal X-ray analysis and supported by variable-temperature NMR studies. The anion binding properties of the receptors were evaluated via (1)H NMR titration experiments, showing intermolecular interactions with H(2)PO(4)(-), AcO(-), BzO(-), and Cl(-) ions. The host molecule bearing 4-nitrophenyl substituents on the bisurea binding pocket showed association constants in the range of 200-400 M(-1) in the strongly competitive solvent mixture of DMSO/0.5% H(2)O.
authors.affiliation: Molecular Design and Synthesis, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Van Rossom
authors.forename: Jef
authors.initials: J
authors.lastname: Caers
authors.forename: Koen
authors.initials: K
authors.lastname: Robeyns
authors.forename: Luc
authors.initials: L
authors.lastname: Van Meervelt
authors.forename: Wouter
authors.initials: W
authors.lastname: Maes
authors.forename: Wim
authors.initials: W
authors.lastname: Dehaen
mesh_terms: D000838:Anions / Q000737:chemistry*; D001665:Binding Sites; D047250:Calixarenes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D006860:Hydrogen Bonding; D047028:Macrocyclic Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011743:Pyrimidines / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*
chemical_list: D000838:Anions; D047028:Macrocyclic Compounds; D011743:Pyrimidines; D012997:Solvents; D047250:Calixarenes; C030986:pyrimidine; D004121:Dimethyl Sulfoxide