title: Enhanced thermodynamic and kinetic stability of calix[4]arene dimers locked in the cone conformation.
abstract: Wide rim tetraurea derivatives (2a,b) have been prepared from a calix[4]arene rigidified in the cone conformation by two diethyleneglycol ether bridges between adjacent oxygens. In comparison to the analogous tetraurea derivatives (3a,b) of a tetrapentoxy calix[4]arene, 2a,b show an increased thermodynamic stability in mixtures of CDCl(3) and DMSO-d(6). Their kinetic stability as expressed by the rate of guest exchange (benzene or cyclohexane against the solvent benzene-d(6)) is also strongly increased by factors of 30-38. Noticeable differences for the inclusion of selected guests are found.
authors.affiliation: Abteilung Lehramt Chemie, Fachbereich Chemie und Pharmazie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55099, Mainz, Germany.
authors.forename: Myroslav O
authors.initials: MO
authors.lastname: Vysotsky
authors.forename: Oliver
authors.initials: O
authors.lastname: Mogck
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Rudzevich
authors.forename: Alexander
authors.initials: A
authors.lastname: Shivanyuk
authors.forename: Volker
authors.initials: V
authors.lastname: Böhmer
authors.forename: Marcus S
authors.initials: MS
authors.lastname: Brody
authors.forename: Young Lag
authors.initials: YL
authors.lastname: Cho
authors.forename: Dmitry M
authors.initials: DM
authors.lastname: Rudkevich
authors.forename: Julius
authors.initials: J
authors.lastname: Rebek
mesh_terms: D047250:Calixarenes; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry*; D013816:Thermodynamics; D014508:Urea / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D010636:Phenols; C121325:calix(4)arene; D047250:Calixarenes; D014508:Urea