title: Molecules with new topologies derived from hydrogen-bonded dimers of tetraurea calix[4]arenes.
abstract: Tetraurea calix[4]arenes 2 have been synthesized in which two adjacent aryl urea residues are connected to a loop by an aliphatic chain -O-(CH(2))(n)-O-. The remaining urea residues have a bulky 3,5-di-tert-butylphenyl residue and an omega-alkenyloxyphenyl residue. Since this bulky residue cannot pass through the loop, only one homodimer (22) is formed in apolar solvents, for steric reasons, in which the two alkenyl residues penetrate the two macrocyclic loops. Covalent connection of these alkenyl groups by olefin metathesis followed by hydrogenation creates compounds 3, which consist of molecules with hitherto unknown topology. Their molecular structure was confirmed by (1)H NMR spectroscopy and ESIMS, and for one example by single-crystal X-ray analysis.
authors: Abteilung Lehramt Chemie, Fachbereich Chemie, Pharmazie und Geowissenschaften, Johannes Gutenberg-Universität Mainz, Duesbergweg, Mainz, Germany.
authors: Anca
authors: A
authors: Bogdan
authors: Michael
authors: M
authors: Bolte
authors: Volker
authors: V
authors: Böhmer
mesh_terms: D047250:Calixarenes / Q000737:chemistry*; D019281:Dimerization; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010636:Phenols / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D010636:Phenols; C121325:calix(4)arene; D047250:Calixarenes