title: Two-dimensional organization of mono- and bisurea supramolecular polymers studied by scanning tunneling microscopy.
abstract: Scanning tunneling microscopy (STM) of mono- and bisurea-functionalized oligo(p-phenylenevinylene)s at solid/liquid interface visualized two-dimensionally-ordered double columnar structures of pi-conjugated segments scaffolded by one-dimensional supramolecular polymerization of urea hydrogen-bonding units. In contrast to a persistent alignment of the bisurea compound supported by twofold intermolecular urea-urea hydrogen-bonding, the building blocks in the monourea double columns shows dynamic fluctuation and defects because of their rotational motion around urea-urea hydrogen-bonding axis and/or adsorption-desorption of the individual molecules from the surface. Self-assembled structures of mono- and bisurea compounds at solid/liquid interface revealed by STM can be related to their gelation abilities in organic solvents.
authors.affiliation: Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kikkawa
authors.forename: Shun
authors.initials: S
authors.lastname: Kubota
authors.forename: Takashi
authors.initials: T
authors.lastname: Karatsu
authors.forename: Akihide
authors.initials: A
authors.lastname: Kitamura
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kanesato
authors.forename: Shiki
authors.initials: S
authors.lastname: Yagai