Two-dimensional organization of mono- and bisurea supramolecular polymers studied by scanning tunneling microscopy.
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.
Kikkawa
Yoshihiro
Y
Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan.
Kubota
Shun
S
Karatsu
Takashi
T
Kitamura
Akihide
A
Kanesato
Masatoshi
M
Yagai
Shiki
S