Studies on the syntheses of azole derivatives. Part III. Syntheses of 1-Phenyl-Δ2-1,2,4-triazolin-5-one and 4-Phenyl-Δ2-1,3,4-oxadiazolin-5-one Derivatives by Fusion of 1-Phenyl-2-acylhydrazine with Urea

Fusion of 1-phenyl-2-acylhydrazine (III) with urea gave Δ²-1,2,4-triazolin-5-one and Δ²-1,3,4-oxadiazolin-5-one derivatives together with various by-products. Furthermore, various derivatives were synthesized for the purpose of examination in a pharmacological screening test.     

Three-vessel study of cerebral blood flow using phase-contrast magnetic resonance imaging: Effect of physical characteristics

The development of phase-contrast magnetic resonance imaging (P-C MRI) provides a noninvasive method for measurement of volumetric blood flow (VFR). We performed P-C MRI to study the effects of physical characteristics on cerebral blood flow. VFR of the left and right internal carotid arteries and basilar artery were measured using P-C MRI and total cerebral blood flow (tCBF) was calculated by summing up the VFR values in the three vessels. Moreover, we investigated the changes in these blood flows as influenced by age, head size, height, weight, body surface area, and handedness. The blood flows were 142 ± 58 ml/min (mean ± standard deviation) in the basilar artery; and 229 ± 86 ml/min in the left, and 223 ± 58 ml/min in the right internal carotid artery; and tCBF was 617 ± 128 ml/min. Significant increases were observed in head size-related change of VFR in the basilar artery (p = .028) and height-related change of tCBF (p = .045). The other characteristics did not significantly influence any VFR. The results suggest that head size and height may reflect CBF, and that these effects should be considered when changes of CBF are diagnosed. Phase-contrast MRI is useful for a noninvasive and rapid analysis of cerebral VFR and has potential for clinical use.     

Synthesis and photophysical properties of ferrocene-oligothiophene-fullerene triads

To promote photoinduced charge separation previously observed for the oligothiophene-fullerene dyads (nT-C60), we have designed an additional attachment with a strongly electron-donating ferrocene at the unsubstituted terminal site of the oligothiophene and synthesized two types of the ferrocene-oligothiophene-fullerene triads, Fc-nT-C60 directly linking the ferrocene to the oligothiophene and Fc-tm-nT-C60 inserting a trimethylene spacer between the ferrocene and the oligothiophene. For the central oligothiophene of the triads, a homologous series of quaterthiophene (4T), octithiophene (8T), and duodecithiophene (12T) are systematically examined. The cyclic voltammograms and electronic absorption spectra of Fc-nT-C60 indicate conjugation between the ferrocene and oligothiophene components. The emission spectra of Fc-nT-C60 measured in toluene demonstrate that the fluorescence of the oligothiophene is markedly quenched, as compared to that observed for the dyads nT-C60. This quenching is explained in terms of the involvement of intramolecular electron transfer in the photophysical decay process. The additionally conjugated ferrocene evidently contributes to the stabilization of charge separation states, thus promoting intramolecular electron transfer. This is corroborated by the observation that the emission spectra of the nonconjugated triads Fc-tm-nT-C60 are essentially similar to the corresponding dyads nT-C60.     

Selenium-Containing π-Conjugated Compounds for Electronic Molecular Materials

Abstract

Novel selenium-containing π-conjugated compounds have been studied for the development of organic metals, superconductors, and field-effect-transistors. Methylenedithiotetraselenafulvalene (MDT-TSF) and its related electron donors are effectively synthesized by the recently developed synthetic method consisting of the one-pot formation of 1,3-diselenole-2-selones, the deprotection/realkylation procedure of the protected tetrachalcogenafulvalene-thiolate and -selenolate, and the ring closing reaction via trans-alkylation on sulfur or selenium atom. These new compounds serve as good electron donors for developing not only highly conducting charge-transfer salts (> 10 ³ S cm^?1) but also superconducting salts. Among six selenium-containing methylenedichalcogeno-tetrachalcogenafulvalenes, we found that four of them can produce superconducting salts, indicating that the present compounds are superior class of electron donors.

For the development of high-performance organic semiconductors for organic field effect transistor (OFET) devices, we focused our attention to selenophene-containing acene-type compounds, namely benzo[1,2-b:4,5-b′]diselenophene (BDS) derivatives hitherto unknown. A new synthetic method for BDS derivatives consisting of double heterocycle-formation on the central benzene ring has been established and has made it possible to synthesize a range of BDS derivatives. Among them, 2,6-diphenyl derivative (DPh-BDS) shows very high hole mobility of 0.17 cm ² /Vs, which is classified into the highest class of field-effect mobility of organic thin films.     

High-yield Carbonization of Cellulose by Sulfuric Acid Impregnation

The carbonization of cellulose with sulfuric acid impregnation was studied by thermogravimetric analysis and scanning electron microscopy. The mass yield of carbon after 800°C treatment in nitrogen increased to 2–3 times by addition of small amounts of sulfuric acid. The sulfuric acid is considered to work as dehydration catalyst, thus suppressing the release of volatile organic substances. The shrinkage of the sample during carbonization was also significantly reduced by the addition of sulfuric acid.     

Immobilization of protein on cellulose hydrogel

A technique of immobilizing an enzyme/antibody was developed using cellulose hydrogel prepared from an aqueous alkali-urea solvent. Partial oxidation by sodium periodate activated the cellulose gel for introducing aldehyde groups. Proteins were covalently introduced to cellulose gel by a Schiff base formation between the aldehyde and the amino groups of proteins, and stabilized by a reduction of imines. Coloring reactions confirmed the high activity of the immobilized enzymes. The activity of the immobilized enzymes increased with aldehyde content, but the effect leveled off at a low degree of oxidation, at approximately 8.1 of oxidized glucose/100 glucose unit. The amount of immobilized peroxidase calculated from the activity was 8.0 ng/g for an aldehyde content of 0.18 mmol/g: 14.6 ng/g for both 0.46 mmol/g and 1.04 mmol/g. The same method could be applied to the peroxidase antibody. Thus, various active proteins could be immobilized on cellulose gels by mild and facile processing. Owing to high mechanical and chemical stability of cellulose, this technique and resulting materials are potentially useful in biochemical processing and sensing technologies.     

Plasma Grooving System Using Atmospheric Pressure Surface Discharge Plasma

To fabricate narrow front contact grooves on a single crystalline silicon solar cell, we carried out etching of a silicon nitride film on a silicon substrate using the surface discharge plasma operated at atmospheric pressure. The control of groove width by changing the discharge voltage (V _d) and the length of a back electrode (l) used for formation of the surface discharge was examined. It was found that narrower electrode grooves could be obtained when l was short. For the case of l = 2 mm, the narrowest groove of 116 μm was obtained at V _d = 3.5 kV and the processing time (t _e) of 10 s.     

Stoichiometry and stability of cellulose-hydrazine complexes

Highly crystalline cellulose samples from green algae (cellulose I) and mercerized ramie (cellulose II) were treated with anhydrous hydrazine and the resulting complexes were analyzed by synchrotron X-ray diffraction and thermogravimetry. Cellulose I-hydrazine complex could be fully described by a two-chain monoclinic unit cell, a = 0.879 nm, b = 1.076 nm, c = 1.038 nm, and γ = 122.0°, with space group P2₁. Cellulose II-hydrazine complex prepared from mercerized ramie gave a different two-chain monoclinic unit cell, a = 1.042 nm, b = 1.046 nm, c = 1.038 nm, γ = 129.7°, also with space group P2₁. Though having different crystal structures, the number of hydrazine molecules per glucopyranoside residue was 0.82 for cellulose I-complex and 0.93 for cellulose II-complex, probable stoichiometric value of 1.0. Hydrazine could be extracted from the complexes by organic solvents retaining the crystalline orders, resulting in the allomorphic conversion to cellulose III_I and cellulose III_II, both having non-staggered chain arrangements. These features are similar to those of cellulose-ethylenediamine complexes.     

Palladium-catalyzed intramolecular hydroarylation of 4-benzofuranyl alkynoates. Approach to angelicin derivatives

Intramolecular hydroarylation of 4-benzofuranyl alkynoates using Pd(OAc)(2) as catalyst took place selectively and efficiently, giving angular furocoumarin derivatives in high yields. The parent angelicin was obtained in 80% yield by this method. The starting 4-benzofuranyl alkynoates were easily accessible from readily available 4-hydroxybenzofurans and alkynoic acids.     

Pd-catalyzed reductive cleavage of alkyl aryl sulfides with triethylsilane that is accelerated by trialkylsilyl chloride

The palladium-catalyzed reductive cleavage of alkyl aryl sulfides to afford the corresponding arenes in high yield, which is both accelerated and exhibits increased functional group selectivity in the presence of TMSCl, is described. This ligand-free reaction features mild conditions, easy operation, use of readily available reagents, and high functional group selectivity.