No abstract

A diarylethene having 2-cyanopyrrole rings turned blue upon UV irradiation in ethyl acetate. The colored form was unstable and returned to the colorless open-ring form with a half-life time of 37 s at room temperature. The activation energy of the thermal fading was obtained to be 32.5 kJ / mol, which is less than half of that of spironaphthoxazine.

Stable nano-sized gold and palladium particles dispersed in composites were prepared by way of the thermal relaxation technique. Continuous formation and dispersion of metal particles into a nylon-11 oligomer film were achieved by the heating of the oligomer film to 46 • C during a vapor deposition of the metal. The mean particle size in the composite was 4.4 nm (S.D. = 1.7 nm) for the gold particles prepared by the deposition of about 3.6 × 10 18 atoms cm −2 . For the palladium particles the particle size was 2.3 nm (S.D. = 0.67 nm) and the deposition 4.2 × 10 18 atoms cm −2 . The obtained composite of gold or palladium particles was readily dissolved in CH 2 Cl 2 , producing stable colloidal solutions. The procedure reported here is very effective for preparing a great deal of metal particles dispersed in composites.PACS. 81.20.Zx Other methods of materials synthesis and materials processing -61.46.+w Clusters, nanoparticles, and nanocrystalline materials -07.30.-t Vacuum apparatus and techniques

Gold catalysts supported on titanium oxide ( TiO 2 ) have been prepared by using nano-sized gold particle/nylon-11 oligomer composites. The composite was prepared through vapor-deposition of gold onto a nylon-11 oligomer film followed by heat treatment. The gold particles/nylon-11 oligomer composite in solution was adsorbed rapidly on the surface of TiO 2 . When the gold particles/nylon-11 oligomer composite adsorbed on TiO 2 was calcined at various temperatures in air, nano-sized gold particles were supported directly on the surface of TiO 2 without coagulation. The catalytic activity of the gold particles for oxidation of CO was measured in a flow type reactor. The catalytic activity of gold supported on TiO 2 prepared by a one-stage calcination was not so high as that of gold catalysts reported previously. This result was considered to be due to growth of the size of the gold particles during calcination. When the calcination was carried out in two stages (the first at 500 °C in vacuum, and the second at 400 °C in air), the growth of the size of the gold particles was suppressed considerably. The supported gold catalyst thus obtained showed very high activity for the oxidation of CO, with a temperature of −10 °C for 50% conversion of CO.

SynopsisThin films were prepared on substrates, cleavage surface of KCl single crystal, and metallic copper, by reaction of 1,2,4,5-tetracyanobenzene with the substrate at various temperatures. The films were characterized by elemental analysis, IR, and W / V I S spectroscopies. The films were observed by scanning electron microscopy. The films produced on copper a t temperatures between 300 and 400°C consisted of copper octacyanophthalocyanine and its polymer with ladder structure. The ratio of polymer to monomer increased with elevating the reaction temperature. The films were composed of ribbon-like crystals. The film produced on copper above 450°C was composed of an amorphous and continuous layer of polymeric copper phthalocyanine. The film produced on KCl a t temperatures between 250 and 350°C consisted of potassium octacyanophthalocyanine and its polymer with ladder structure. The film produced on KC1 above 450°C was polymeric potassium phthalocyanine. Those films contained more h e t a l content than that required stoichiometrical.