title: Light-reducible dissipative nanostructures formed at the solid-liquid interface.
abstract: Dissipative structures are macroscopic or even larger ordered structures that emerge under conditions far from thermodynamic equilibrium. In contrast, molecular self-assembly has been investigated near at the thermodynamic equilibrium, which provides basically smaller, nano-to-micron sized structures. In terms of the formation principles, there exists an essential gap between the dissipative structures and molecular self-assemblies. To fill this gap, molecular self-assembly of light-reducible organic-inorganic ion pairs was investigated under far-from-equilibrium conditions. When solid films of tetraalkylammonium hexafluorophosphate were immersed in aqueous Au(OH)4(-) and immediately photoirradiated, gold nanowires are formed at the solid-aqueous interface. On the other hand, such nanowires were not formed when the photoirradiation was conducted for the specimens after a prolonged immersion period of 60 min. These observations indicate spontaneous growth of dissipative nanofibrous self-assemblies consisting of light-reducible ion pairs [tetraalkylammonium ion][Au(OH)4(-)] at the interface and their photoreduction to give developed nanowires. These nanowires are not available by the photoreduction of Au(OH)4(-) ions under conditions near at the thermodynamic equilibrium. A picture for the dissipative nanostructures is obtained: the formation of amphiphilic light-reducible nanowire structures is based on the static self-assembly near at the thermodynamic equilibrium, whereas their spontaneous, anisotropic growth from the interface to the aqueous phase is directed by dynamic, dissipative self-assembly phenomena under the far-from-equilibrium conditions. Thus, the both elements of dissipative self-assembly (dynamic) and static molecular self-assembly fuse together at the nanoscale, which is an essential feature of the dissipative nanostructures.
authors.affiliation: Department of Applied Chemistry, Kinki University , 3-4-1 Kowakae, Higashi-osaka, Osaka 577-8502, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Soejima
authors.forename: Yuta
authors.initials: Y
authors.lastname: Amako
authors.forename: Seishiro
authors.initials: S
authors.lastname: Ito
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kimizuka