Regioselective synthesis of [60]fullerene eta 5-indenide R3C60- and eta 5-cyclopentadienide R5C60- bearing different R groups

Treatment of a 1,7-diorgano[60]fullerene with Grignard reagents or organocopper reagents affords a [60]fullerene indenide or a [60]fullerene cyclopentadienide regioselectively in good to excellent yields. These reactions gave an insight into the reaction mechanism of the organocopper penta-addition reaction of [60]fullerene, giving [60]fullerene cyclopentadienide in quantitative yield.     

Photocurrent amplification by an energy/electron transfer cascade in polymer Langmuir-Blodgett films

Effective photocurrent generation by visible light irradiation on hetero-deposited polymer Langmuir-Blodgett (LB) films containing tris(bipyridine) ruthenium(II) (Ru(bpy)3(2+)) and anthracene derivatives was observed. The photocurrent amplification was found to be assisted by the photoinduced energy/electron transfer cascade, which consists of the interlayer triplet-triplet energy transfer process from photoexcited Ru(bpy)3(2+) to anthracene, and then electron transfer processes from the triplet anthracene to a viologen acceptor, from Ru(bpy)3(2+) to the oxidized anthracene and from the electrode to Ru(bpy)3(3+).     

Specific molecule localization in microchannel laminar flow and its application for non-immobilized-probe analysis

Microfluidic systems enable superior control of fluidics. We have developed a novel size-separation method utilizing secondary flow within a microchannel. Using confocal fluorescence microscopy and computer simulation, we confirmed that separation occurred as a result of specific molecular localization in the curving part of the microchannel. Maximum separation efficiency was achieved by optimizing microchannel design and flow rate for individual separation targets. In addition, more effective separation was achieved by use of plural microchannel curves. This method was used for sequence-selective DNA sensing. Double-stranded DNA formed by hybridization between target DNA and a complementary probe had different elution profiles from those of the single-stranded non-complementary sequence. Moreover, the response depends on the length of the DNA molecules. This method does not require immobilization of either probe or target DNA, because all reactions occurred in the solution phase. Such features may reduce experimental error and the difference between data from different operators.     

Application of a microfluidic reaction system for CdSe nanocrystal preparation: their growth kinetics and photoluminescence analysis

We used a microreactor for CdSe nanocrystal preparation and explored the effects of experimental conditions on the properties of the products. The particle growth kinetics and photoluminescence properties of the nanocrystals showed identical trends to previous reports, indicating the efficiency of the current method for analysis of rapid nanocrystal synthesis as well as industrial production of CdSe nanocrystals.     

Korngrößenänderung beim Carburieren von Wolfram und Sintern von Wolframcarbid

The change of grain size during each stage of the process was studied, mainly by optical and electron microscopy. The grain size has a marked effect on the properties of cemented carbide. In order to determine the process of formation of WC powder, the cross section and the surface of the carburized powder were examined microscopically. The mechanisms of carburization and grain growth were clarified. The microstructural relationship between the WC powder and the cemented carbide was also determined. The Co from the ball milled WC-Co mixed powder was extracted and the remaining WC powder was studied microscopically and by determining the grain size distribution. Methods of particle crushing and their effect on differences between various forms of WC powder were studied. Grain growth in sintering and the effect of grain size distribution were also studied. It was concluded that grain growth begins long before the appearance of the liquid phase. Finally it was pointed out that the inner structure of WC should be studied at the atomic level.     

Nucleophilic vinylic substitutions of (Z)-(2-aroyloxyvinyl)phenyl-λ-iodanes with tetrabutylammonium halides: vinylic SN2 reactions and ligand coupling on iodine(III)

Treatment of (Z)-(β-benzoyloxyvinyl)phenyl-λ³-iodanes, readily prepared from ethynyl(phenyl)(tetrafluoroborato)-λ³-iodane via stereoselective Michael-type addition of benzoic acids in methanol in the presence of sodium benzoates, with tetrabutylammonium halides in THF at 65 °C results in a vinylic S_N2 reaction to give the inverted (E)-β-benzoyloxyvinyl halides in high yields.     

Novel fluorous prolinol as a pre-catalyst for catalytic asymmetric borane reduction of various ketones

Novel prolinol carrying two perfluorohexylethyl groups at the α-position was prepared from l-proline as a starting chiral substrate. Catalytic asymmetric reduction of various ketones, including mono-, di-, and trifluoromethylated acetophenones, using fluorous oxazaborolidines derived from fluorous prolinol afforded the corresponding alcohols in good to excellent yields and with high enantioselectivities (up to 93.2% ee). The fluorous prolinol was recovered without any fluorous solvents or silica gel by simply cooling the organic phase and filtration.     

Application of semidifferential electroanalysis to anodic stripping voltammetry

A new voltammetric technique, Semidifferential electroanalysis, in which the semiderivative, e, of the current, i, is measured as a function of electrode potential, has been applied for detection in anodic stripping voltammetry. The semiderivative of the current is defined by [fx131-1.tif] Cd²⁺, Pb²⁺, and Tl⁺ in 0.1 M KNO₃ at different pH values were tested as samples on a hanging mercury drop working electrode. Symmetrical sharp peaks were observed for the re-dissolution processes of metal amalgams formed during pre-electrolysis at -1.0 V vs. SCE. The peak potentials of e vs. E curves for the above three amalgams agreed well with the literature values for d.c. polarographic half-wave potentials. The peak heights were proportional to the pre-electrolysis time up to about 5 min, to the potential scan rate in the range 60–160 mV s^-1, and to the concentrations of Cd²⁺, Pb²⁺, and Tl⁺ in the original solution in the range 10^-6–10^-9 M. The relative standard deviation for the determination of Cd²⁺ was about ±4% at the 2 × 10^-5 M level.     

Catalytic determination of ultratrace amounts of Cu(II) by the oxidative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone with N,N-dimethylaniline

Summary Copper (II) catalyzes the coupling reaction of 3-methyl-2-benzothiazolinone hydrazone (MBTH) with N,N-dimethylaniline (DMA) to form an intensely colored dye (_max=590 nm) in the presence of hydrogen peroxide and ammonia as an activator. On the basis of this reaction, a highly sensitive and selective catalytic method for Cu(II) has been developed. As little as 10^–9 M Cu(II) can be determined by measuring the absorbance of the reaction product at a fixed time (20 min at 40°C). Sandell's sensitivity calculated from the working curve is 1.3×10^–3 ng cm^–2. The method was applied to water analysis and some comments on the analysis of copper in river water were added.Presented at the 1st International Symposium on Kinetics in Analytical Chemistry, Córdoba, Spain, September 28th, 1983.