Voltammetric evaluation on poly α-aspartic acid-zinc ion complex in the helix-coil transition pH region.

Helix-coil transitions of poly α-aspartic acid (PASP) were studied by dc polarography in the presence of Zn(2+) as a marker attached to the polymer. The diffusion current (i(d)) of Zn(2+) declined markedly in the pH range of 3.5-7.

Preparation of Langmuir-Blodgett films of aligned sepiolite fibers and orientation of methylene blue molecules adsorbed on the film.

Sepiolite is a clay mineral with a fibrous morphology; the fibers possess rectangular channels along the fiber direction, and have cation-exchange ability. Amphiphilic octadecylammonium cations (ODAH(+)) spread at an interface between the air and a dispersion of sepiolite fibers have hybridized with the fibers to form a floating monolayer. Surface pressure-molecular area isotherms did not indicate clear collapse points of the hybrid monolayers.

Photocatalytic decomposition of an alkylammonium cation in a Langmuir-Blodgett film of a titania nanosheet.

The formation of inorganic-organic hybrid films of a titania nanosheet and an amphiphilic alkylammonium cation has been investigated, and the photocatalytic decomposition of the alkylammonium cation in the film has been pursued. When a solution of the amphiphilic alkylammonium salt (octadecylammonium chloride: ODAH+ Cl-) was spread on an interface between the air and a titania nanosheet suspension, the negatively charged nanosheets were adsorbed onto the floating monolayer of ODAH+ to form a hybrid monolayer. The hybridization was confirmed by pi-A isotherm measurements, atomic force microscopy, and X-ray photoelectron spectroscopy.

Formation of Langmuir-Blodgett films of a clay and a water-soluble alkylammonium cation.

We have studied the formation of ultrathin hybrid films composed of a water-soluble alkylammonium cation (trimethyloctadecylammonium caiton: TMODAH+) and clay nanosheets at an air-water interface. When a chloroform solution of the ammonium salt of TMODAH+Cl- was spread onto a surface of an aqueous clay suspension in a Langmuir trough, a stable monolayer of the water-soluble ammonium cation was formed by hybridization with the clay nanosheets at the air-water interface. Surface pressure--molecular area (pi-A) isotherm curve of the hybrid monolayer shifted to the smaller molecular area side with the increase in the concentration of the ammonium salt in the solution or with the decrease in that of the clay in the suspension.

Two-dimensional molecular ordering of Os(II) complexes in organo-clay hybrid ultrathin films.

An ordered structure of [OsL(3)](2+)(L = 2, 2'-bipyridine or 1, 10-phenanthroline) layer in an ultrathin film composed of the complex cations, clay nanosheets and alkylammonium cations is reported on the basis of its in-plane X-ray diffraction and polarized electronic spectral data.