One-dimensional CuBr4(2-) ion array and CuBr3- ion chain included in the pi conducting framework composed of bis(methylthio)tetrathiafulvalenothioquinone-1,3-dithiocarbonatodithiolemethide molecules

The reaction of a new donor molecule having a planar but largely bent skeleton, bis(methylthio)tetrathiafulvalenothioquinone-1,3-dithiocarbonatodithiolemethide (1), with CuBr(2) in CH(3)CN/CS(2) afforded a black-colored crystal with a formula of 1(4).CuBr(4).2CuBr(3). In the crystal 1 molecules are one-dimensionally stacked to form half-cut pipelike columns, which are arranged to construct two different shapes of channels included by a one-dimensional array of CuBr(4)(2)(-) ions and a bibromide-bridged linear chain of CuBr(3)(-) ions with a square-pyramidal geometry at the Cu atom, [CuBr(3)(-)](n)(), respectively. The room-temperature electrical conductivity on the single crystal of 1(4).CuBr(4).2CuBr(3) was 2.0 x 10(-)(2) S cm(-)(1), and the temperature dependence of electrical conductivity was semiconducting with a large activation energy of 160 meV. The interactions between the neighboring Cu(II) d spins in the one-dimensional S = 1/2 spin systems due to CuBr(4)(2)(-) ions and CuBr(3)(-) ions in [CuBr(3)(-)](n)() were both antiferromagnetic, and the magnitudes were moderate (Weiss temperature, THETAV; = -18 K) in the former spin system and fairly large (coupling constant, J/k(B) = -120 K) in the latter spin system, which was in marked contrast to a moderate and ferromagnetic [CuBr(3)(-)](n)() chain in the cyclohexylammonium salt already known.     

Removal of proteinaceous soils using hydroxyl radicals generated by the electrolysis of hydrogen peroxide

We have developed here for the first time a novel method to generate hydroxyl radicals, *OH, by applying slightly negative electric potentials (-0.2--0.8 V vs Ag/AgCl) to the surface of a metal (or metal oxide) that is in contact with hydrogen peroxide solution containing a supporting electrolyte. Namely, *OH radicals were generated at the surface by the electrolysis of hydrogen peroxide according to the equation, H2O2+e- --> *OH+OH-. This method was used to clean a stainless steel fouled with a model protein, beta-lactoglobulin. The *OHs generated at the surface were effective in removing beta-lactoglobulin that had been irreversibly adsorbed, by several minutes of treatment at room temperature (22+/-2 degrees C). The removal rates measured for various concentrations of H2O2 and supporting electrolyte and different potentials were determined exclusively by the electric current.     

Cobalt Ion-Doped TiO(2) Photocatalyst Response to Visible Light

Photocatalytic activity under visible light irradiation was generated by doping a small amount of Co(2+) ions into TiO(2) particles. Nanometer-sized particles with the composition xCoO-(100-x) TiO(2) (xCo/TiO(2); 0300 nm) light irradiation but also induced the visible light (lambda>400 nm) response. The highest photocatalytic activities were obtained at x=0.03 for both irradiations. Copyright 2000 Academic Press.     

Semi-rigid thermotropic liquid-crystalline copolycarbonates comprising main-chain hexafluoropentane segments

Novel semi-rigid fluorocarbon-containing coplycarbonates composed of biphenyl moiety and rigid rod-like hexafluoropentane chain were prepared by melt polycondensation of 6,6′-(biphenyl-4,4′-diyldioxy)dihexanol ( 1 ) and 2,2,3,3,4,4-hexafluoro-1,5-pentanediol ( 2 ) with alkylene diphenyl dicarbonates 3 of various aliphatic lengths (m = 6, 8, 10 and 12). The structures of the copolymers 4 were confirmed by FT-IR, ¹H and ¹³C NMR spectra and elemental analyses. The thermal and liquid-crystalline (LC) properties were examined by differential scanning calorimetry (DSC), polarizing microscopy and temperature-changeable X-ray analyses. These measurements indicated that the copolymers show well-defined thermotropic nematic textures and have block-like sequences. It is suggested that the introduction of the hexafluoropentane chain into the main chain gives more stable LC phases.     

A uniform and one‐dimensional stacking of 2,5‐di­chloro­tetra­cyano­quinodimethanide mol­ecules in the tetra­methyl­arsonium salt

In the tetra­methyl­arsonium salt of 2,5‐di­chloro‐7,7,8,8‐tetra­cyano­quinodimethanide [systematic name: tetra­methyl­arson­ium 2,2′‐(2,5‐dichlorocyclohexa‐2,5‐diene‐1,4‐diylidene)bis(propanedinitrile)], C₄H₁₂As⁺·C₁₂H₂Cl₂N₄^? or [As(CH₃)₄](C₁₂H₂Cl₂N₄), the cation lies disordered about a twofold axis and the radical ion lies about an inversion center forming a uniform [interplanar distance 3.35 (2) Å] and one‐dimensional stacking without any slip. The electrical conductivity of the single crystal at room temperature was less than 10^?9 S cm^?1, and the temperature dependence of para­magnetic susceptibility obeyed a one‐dimensional antiferromagnetic Heisenberg model with a spin‐exchange integral of 83 K in the temperature range 1.8–320.0 K.     

Sub‐Bandgap Excitation‐Induced Electron Injection from CdSe Quantum Dots to TiO2 in a Directly Coupled System

We show that the sub‐bandgap excitation of a directly coupled CdSe quantum dot (QD)–TiO₂ system induces electron injection from CdSe levels to the conduction band of TiO₂, leading to spectral extension of the light response. We anticipate that this study presents a useful guideline for improving the conversion efficiency of QD‐sensitized solar cells.     

Regioselective synthesis of 6-alkylated lumazine derivatives

The regiospecific synthesis of alkylated lumazines is achieved by hetero Diels-Alder addition between an oxadiazinone 2 and enamine. The reactions proceed stepwise by cycloaddition, decarboxylation and deamination to produce the 6-alkylated lumazines.     

Structural analysis of SiO2 gel films by high energy electron diffraction

The structure of SiO₂ gel-films prepared from acid and basic TEOS solutions is analyzed by high energy transmission electron diffraction method. The Si-O bond length of gel-films is 1.58 to 1.60 Å, which is shorter than that of vitreous silica (1.61 Å) but similar to that of 80 Å thick evaporated a-SiO₂ film. An atomic pair peak with 0.81 Å distance exists on the reduced radial distribution functions of the gel-films, which is believed to be O-H, but being smaller than that of H₂O (0.969 Å).     

Realignment process of actin stress fibers in single living cells studied by focused femtosecond laser irradiation

Three-dimensional dissection of a single actin stress fiber in a living cell was performed based on multi-photon absorption of a focused femtosecond laser pulse. The realignment process of an actin stress fiber was investigated after its direct cutting by a single-shot femtosecond laser pulse irradiation by high-speed transmission and fluorescence imaging methods. It was confirmed that mechanical force led by the femtosecond laser cutting propagates to entire cell through the cytockelton in a 100 μs time scale. The cut actin stress fiber was realigned in the time scale of a few tens of minutes. The dynamic analysis of the realignment induced by single-shot femtosecond laser gives new information on cell activity.