title: Self-assembled pyrazinacene nanotubes.
abstract: Nanotubes of a pentacene derivative, 6,13-bis(1-n-dodecyl)-[a,c,l,n]-tetrabenzo-5,6,7,12,13,14-hexaazapentacene, have been prepared by a hierarchical self-assembly mechanism. The oligoazaacenes 1-3, referred to as pyrazinacenes due to their structures of linearly fused pyrazine heterocycles, can also be considered as two azatriphenylenes fused through a reduced pyrazine ring. Dissolution of 6,13-bis(1-n-dodecyl)-[a,c,l,n]-tetrabenzo-5,6,7,12,13,14-hexaaza pentacene in nearly boiling toluene followed by standing of the solution at room temperature yields self-assembled (sa) pyrazinacene (Pa) nanotubes (NT's), or sa-PaNTs. Self-assembled-PaNTs are formed after initial aggregation of the pyrazinacene giving a 130-nm-wide 2-dimensional tape followed by helical twisting of this tape into a hollow cylindrical form of 150-200 nm diameter which can exceed 10 μm in length. The morphologies of the tape and nanotube structures were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and electron absorption spectroscopy (UV/Vis). The latter indicates that the tubes may be formed by chromophore J-aggregation. Also, high resolution TEM of the tubes reveals that they can be composed of several tapes while powder X-ray diffraction revealed the lamellar structure of the tapes composing the tubes.
authors.affiliation: WPI-Center for Materials Nanoarchitectonics, National Institute of Materials Science, Namiki 1-1, Tsukuba, Ibaraki, 305-0044, Japan.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Richards
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Hill
authors.forename: Jan
authors.initials: J
authors.lastname: Labuta
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Wakayama
authors.forename: Misaho
authors.initials: M
authors.lastname: Akada
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Ariga