Takayuki Azuma

A Facile Preparation of Aromatic Anion Radicals by Ultrasound Irradiation

Abstract Aromatic compounds such as naphthalene and biphenyl are reduced by alkali metals, giving armatic anion radicals which are useful as strong bases in organic synthesis,1 as initiators of polymerization2 and oligomerization,3 and also as a medium for n-type doping in organic semiconductor like (CH)X.4 Howerver, preparation of such reagents requires anhydrous and oxygen free reaction conditions, use of carefully dried solvent being requisite for the success of the reaction. In addition, long inductin time is often observedwhen alkail metal cuts are used. Thus, employment of evaporated alkali metal film or finely dispersed metal alkali was generally recommended.5.

Photocatalytic carbon–carbon bond formation with concurrent hydrogen evolution on colloidal zinc sulphide

In the photocatalytic system containing colloidal ZnS, water, and organic substrates such as triethylamine, tetrahydrofuran, or methanol, oxidative carbon–carbon bond formation occurs with efficient reductive H2 evolution, to give the dimeric products 2,3-bis(diethylamino)butane, 2,2′-bitetrahydrofuryl, or ethylene glycol, respectively.

Conducting Polymer Prepared from Teflon

Conducting polymer is prepared from teflon by treatment with a THF solution of alkali-naphthalide. The electrical conductivity of this film is of the order 10-5-10-4 (Ωcm)-1 which is higher than that of teflon by more than ten orders of magnitude and comparable with that of trans (CH)x. The observed small activation energy of the conductivity seems to indicate that this material is slightly doped during the preparation process, as in the case of (CH)x.

Photoinduced electron transfer at a gold electrode modified with a self-assembled monolayer of fullerene

A stable anodic photocurrent was observed in the presence of an electron sacrificer when a gold electrode modified with a self-assembled monolayer of C60 was illuminated with monochromic light, indicating the generation of a vectorial electron flow from the electron donor to the gold electrode via the excited states of C60.

Semiconductor photocatalysis. Part 4. Hydrogen evolution and photoredox reactions of cyclic ethers catalysed by zinc sulphide

ZnS-catalysed photoredox reactions of aqueous solutions of cyclic ethers, i.e. tetrahydrofuran, dihydrofurans, 2,5-dimethyltetrahydrofuran, 3-methyloxetane, 1,4-dioxane, and tetrahydropyran are described. A freshly prepared ZnS suspension displays efficient and selective photocatalysis especially for furan derivatives under band-gap irradiation (> 290 nm); reduction of water by the conduction band electrons generates H2 and one-hole oxidation of the substrates leads to carbon–carbon bond formation through coupling of intermediary radicals. In the photolysis of tetrahydrofuran, oligomerization from the dimeric product (1) to octamer was observed with efficient H2 evolution (φ½H2= 0.13–0.62). Further oxidation of intermediary radicals and photoreduction of the resulting oxidation products were also confirmed; e.g. photolysis of 2,5-dimethyltetrahydrofuran gave exclusively the ring-opened product (9) with its photoreduced product, hexane-2,5-diol (10).

Structure and photoelectrochemical properties of porphyrin-linked fullerenes on a gold surface using a self-assembled monolayer technique

Self-assembled monolayers (SAMs) have recently attracted much attention as a new methodology among a variety of thin film preparation. There have been several reports of fullerene SAM. These fullerene thin films seem to be the most promising candidates for realizing photovoltaic and optoelectronic devices at the nano-scale level. We have applied this technique to donor-linked fullerene systems and have developed supramolecular porphyrin-C60 molecules that are designed to be self-assembled on gold surface. Such systems are expected to mimic supramolecular photoinduced charge-separation events in photosynthesis. Porphyrin-linked C60 bearing a methylthio group was prepared by 1,3- dipolar cycloaddition of the azomethine ylide porphyrin with C60. SAM was formed by soaking Au electrode into a CH2Cl2 solution of the porphyrin-C60 dyad. Structure of the SAM was investigated by spectroscopic methods including X-ray photoelectron spectroscopy and ellipsometry and electrochemical studies. The large photocurrent with a level of sub-(mu) A/cm2 was observed for the photochemical cell in the presence of methyl viologen under illumination with approximately 10 mW/cm2. Possible mechanism for the photocurrent generation is discussed in terms of the photodynamics of porphyrin-linked fullerenes.