Kikuo Ataka

Oxidative reactions by a palladium–alkyl nitrite system☆

Abstract The typical oxidative reactions ((1) dialkyl oxalate synthesis from carbon monoxide, (2) dialkyl carbonate synthesis from carbon monoxide, (3) acetals and ketals synthesis from olefins, and (4) oxidative carbonylation of olefins) catalyzed by palladium in the presence of alkyl nitrites, are described. The mechanistic studies are conducted based on reaction kinetics. In addition, derivation of acetals obtained by olefin oxidation to various useful fine chemicals is also described.

Multilayered ordering of the metal nanoparticles in polymer thin films under photoirradiation.

Interference light-induced photogeneration of metal nanoparticle in polymer films was explored. The nanoparticle was obtained from metal complex homogeneously dispersed in the film. Standing waves resulting from light interference were generated by irradiating nearly monochromatic light to the sample placed on a reflective substrate. During irradiation metal nanoparticles were developed by photoreduction of the metal complexes forming layers rich with particles. These nanoparticle-enriched layers were found to align in parallel to the reflective substrate, and they were separated from each other by a constant spacing. This layer spacing was varied by changing the wavelength and/or the incident angle of the irradiating light. The observed results show that the spatial distribution of the nanoparticles is determined by the optical interference within the film. Surprisingly, regions exist between the nanoparticle-enriched layers where the metal species are not detected. Such regions extends for distances larger than tens of nanometers. This means that the metal complexes initially homogeneously dispersed within the polymer were transported away from certain regions upon photoirradiation. The metal precursors are preferentially photoreduced into the metal nanoparticles at the constructive interference regions. The spatially varying consumption rates of the precursors are considered to lead a concentration gradient, thereby causing a directional diffusion of the unreduced precursors toward the regions where constructive interference occurs.

A Facile, Novel Methodology for Preparation of Multilayer Metal/Polymer Composite Films

Metal/polymer composite multilayer films were prepared through optical interference. Metal nanoparticles were aligned in the row with a constant spacing. This scheme will give a new production methodology for a band-selective optical mirror.