Kouichi Matsumoto

Addition of ArSSAr to dienes via intramolecular C-C bond formation initiated by a catalytic amount of ArS+.

A catalytic amount of electrochemically generated ArS+ (ArS+ = ArS(ArSSAr)+) initiates a cation chain reaction of dienes that involves the addition of ArSSAr associated with stereoselective intramolecular carbon-carbon bond formation, and the direct (in-cell) electrolysis of a mixture of a diene and ArSSAr with a catalytic amount of electricity also effectively initiates the reaction.

SYNTHESIS OF THIOCHROMANS BASED ON INDIRECT CATION POOL METHOD

- A method for the synthesis of thiochromans based on the reactions of stilbenes and alkoxycarbenium ion pools, which were generated and accumulated by the reaction of anodically generated ArS(ArSSAr) + with thioacetals, has been developed.

Studies in the pinacol rearrangement—V : The rearrangements of cis- and trans-1,2-diphenyl-1,2-ditolylethylene oxides

Abstract The intermediate formation of the two epoxides was observed in the perchloric acid-catalysed rearrangement of meso -2,2′-dimethylbenzpinacol (P meso ) to 2-methylbenzoyl tolyl diphenyl methane (K) Two kinds of epoxides were separated with preparative TLC and the configuration ( cis and trans ) of these epoxides was inferred in the light of UV, NMR and IR spectra, dipole moment and kinetic data. The rearrangement rates of these epoxides were measured in HClO 4 -anhydrous acetic acid. Linear correlations of logarithm of the rate constants (log k ) with the Hammett acidity function of the medium ( H 0 ) were obtained, which supports the A-1 mechanism, together with the large positive values of the entropy of activation. It is shown that the perchloric acid-catalysed rearrangement of meso -2,2′-dimethylbenzpinacol (P meso ) occurs via such many kinetically distinguishable routes as the following where C and T are cis - and trans -epoxide respectively. The mechanisms of the rearrangements were discussed from the data of kinetics.

Improved performance of a conducting-bridge random access memory using ionic liquids

The conducting-bridge random access memory (CB-RAM) is a promising candidate for the next-generation memory. In this study, the addition effect of 18 types of ionic liquids (ILs) on the performances of the Cu/HfO2/Pt type CB-RAM has been investigated; the switching voltage was lowered by supplying a trace amount of the IL to the HfO2 layer of the Cu/HfO2/Pt cell. It was revealed that the ionic conductivity (σi) of the IL and the coordinating ability (β) of the anion in the IL towards the copper (Cu) ion are key competing factors that determine the voltage required for the formation of the Cu filament (Vset); the increase in σi and the decrease in β are effective in enhancing the ionization and diffusion of the Cu atoms, resulting in the reduction of Vset. Therefore, among the tested ILs, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([bmim][Tf2N]), 1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)amide ([emim][Tf2N]) and 1-butyl-3-methylimidazolium bis(fluorosulfonyl)amide ([bmim][FSA]), which have high σi and low β values were found to be the best additives for the Cu/HfO2/Pt cell. On the other hand, reset was revealed to occur due to the rupture of the Cu filament by the thermal diffusion of the Cu atoms by Joule heat. Reducing Vset and making a thin filament are effective in reducing the reset voltages. We further traced the origin of the improved dispersion of the switching voltages by the addition of the Cu(Tf2N)2 doped [bmim][Tf2N] to the HfO2 film, which we recently reported. A complex-impedance measurement suggested that the addition of Cu doped IL involves two competing factors: the decline of the Cu ion diffusion and enhancement of the Cu ionization. The balance of these two factors determines the important parameters such as Vset and its dispersion. The performance of the CB-RAM can be optimized by the adjustment of the IL, considering the balance of the competing factors revealed by the present study.

Effects of bromination of poly(3-hexylthiophene) on the performance of bulk heterojunction solar cells

We examined the effects of delocalized π-electrons in poly(3-hexylthiophene) (P3HT) on the photovoltaic properties of a bulk heterojunction (BHJ) solar cell. The π-conjugated length of P3HT was controlled by modification of P3HT through partial bromination at the 4-position of thiophene units. We investigated correlation between the degree of P3HT bromination (2, 11, 22, 37, 66, 84, 100%) and the photovoltaic properties of Br-P3HT:phenyl-C61-butyric acid methyl ester (PCBM) BHJ solar cells. The power conversion efficiency of the 11% Br-P3HT:PCBM solar cell decreased to 56% of that of a pristine P3HT:PCBM solar cell. The main factor contributing to this decrease was lower short circuit currents. The photo absorption spectrum and the X-ray diffraction pattern of the 11% Br-P3HT film showed only slight differences to those of pristine P3HT, indicating the interchain π-stacking of the polymers was almost unaffected by the 11% bromination. These results suggest that an intrachain π-conjugation across more than 10 thiophene rings in the P3HT backbone is necessary to realize efficient charge transport in polymer domains. The 37% Br-P3HT:PCBM cell showed only weak photovoltaic properties; both inter- and intrachain delocalization of π-electrons were disturbed by bromination.

Ionic Liquid Materials Based on Fluoroanions

Ionic liquids based on fluorocomplex and oxofluorocomplex anions exhibit interesting properties in view of a variety of applications. This chapter describes the syntheses, structures, and properties of these ionic liquids. Although highly conductive fluorohydrogenate ionic liquids are attractive as electrolytes in electrochemical applications as they are, they can also be used as precursors for ionic liquids based on other fluorocomplex anions. This synthetic route is suitable to prepare ionic liquids with low halide impurity. Anion dependence of chemical and electrochemical properties for ionic liquids is discussed based on the structures of a series of fluoro- and oxofluorocomplex anions.

Generation and reactions of thiirenium ions by the cation pool method

Thiirenium ions generated and accumulated by low-temperature electrochemical oxidation of disulfides in the presence of alkynes were successfully observed by low-temperature NMR, Raman, and mass spectroscopies and were found to be stable at temperatures below −40 °C. The thiirenium ions showed ambident reactivity toward subsequently added nucleophiles to give either disubstituted alkenes or alkynes depending on the nature of the nucleophiles. PhSSPh anodic oxidation PhS Nu