title: Fourfold tetraurea calix[4]arenes--potential cores for the formation of self-assembled dendrimers.
abstract: Wide rim tetraurea calix[4]arenes monofunctionalized at the narrow rim by COOH or NH2 have been synthesized in five steps from t-butylcalix[4]arene tripropylether. Their covalent linkage via the narrow rim to a central calix[4]arene fixed in the 1,3-alternate conformation led to pentacalix[4]arenes 9 bearing four tetraurea derivatives in the cone conformation in a flexible tetrahedral arrangement. Their self-assembly via the formation of hydrogen bonded dimeric capsules has been studied under different conditions. A fourfold heterodimerisation of tetrakis-tetraurea derivatives of type 9 with tetratosylurea 10 has been confirmed by 1H NMR-spectroscopy and dynamic light scattering.
authors.affiliation: Fachbereich Chemie, Pharmazie und Geowissenschaften, Abteilung Lehramt Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55099 Mainz, Germany.
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Rudzevich
authors.forename: Karl
authors.initials: K
authors.lastname: Fischer
authors.forename: Manfred
authors.initials: M
authors.lastname: Schmidt
authors.forename: Volker
authors.initials: V
authors.lastname: Böhmer