Reaction of sulphoximides with diazomalonate in the presence of Cu-salt : A new synthesis and stereochemistry of optically active oxosulphonium ylides

Sulphoximides (Ia–Ie) were found to react with dimethyl diazomalonate (DDM) in the presence of a catalytic amount of Cu-salts affording the corresponding oxosulphonium ylides in moderate yields. The reaction did not proceed at all under irradiation of UV light. (?)-Methylphenyloxosulphonium bis(methoxycarbonyl)-methylide ((?)-IIb) was obtained from (+)-(S)-methylphenylsulphoximide ((+)-(S)-Ib) together with (?)-(S)-methyl phenyl sulphoxide ((?)-(S)-IIIb) by this reaction. Hydrolysis of (?)-IIb gave (+)-methylphenyloxosulphonium methoxycarbonylmethylide ((+)-IIf) which was converted to (?)-(S)-IIIb upon treatment with dibenzoylethylene. Stereochemical cycle starting from (+)-(S)-Ib to (?)-(S)-IIIb was established and the absolute configurations of both ylides, (?)-IIb and (+)-IIf were assigned as (R)-configuration. The stereochemical courses, namely from (+)-(S)-Ib or (?)-(S)-IIIb to (?)-(R)-IIb or (+)-(R)-IIf to (?)-(S)-IIIb were determined as retention processes. The optical purities of the oxosulphonium ylides obtained from both reactions, (+)-(S)-Ib→(?)-(R)-IIb and (?)-(S)-IIIb→(?)-(R)-IIb, were almost equal. These results indicate that the mechanism of the reaction of sulphoximides with carbenes (or carbenoids) involves the initial formation of the sulphoxides which react subsequently with carbenes to afford the final products.     

Crystal structure of poly(p-benzamide)

Redetermination of the crystal structure of poly(p-benzamide) was made by using newly collected intensity data. The molecular conformation is TCTC, where the internal rotation angles about the N? C bond of the amide group and about the virtual bond of N-phenyl-C are T (trans) and C (cis) conformations, respectively. Two molecular chains pass through a rectangular unit cell with dimension, a = 7.75 Å, b = 5.30 Å, c (fiber axis) = 12.87 Å, and the space group, P2₁2₁2₁-D. The reflection observed at the spacing of 010 may be attributed to the reflection due to another crystal polymorph or the diffuse scattering due to disorder. © 1993 John Wiley & Sons, Inc.     

A novel method for preparation of 2-(methyl- or phehnylthio)alkanoic esters

Ethyl 2-acetylalkanoate gave ethyl 2-(methyl- or phenylthio)alkanoate in high yield on treatment wiht CH₃SSO₂CH₃, PhSSO₂Ph, or PhSSPh in the presence of small excess of EtONa in EtOH. Application of the present method to synthesis of pellitorine and the queen substance is also described.     

Measurements of 127I M?ssbauer spectra for iodine compounds

127I M?ssbauer spectra of good quality were obtained at 20 K using a Zn127mTe source produced by high flux neutron irradiation of 66Zn-126Te at reactor core. The M?ssbauer spectra for KI and some iodine(III) compounds with absorption intensity of about 5% suggest that the 127I M?ssbauer spectroscopy is useful in elucidating the bonding nature of the iodine compounds. Preparative method of the M?ssbauer source and experimental technique are reported in detail.     

Raman spectra of stilbene negative ions in tetrahydrofuran solution

Raman spectra of stilbene mono- and di-negative ions in tetrahydrofuran solution were obtained by Ar⁺ laser exciting lines. A considerable frequency shift was observed for several vibrations in the successive steps: stilbene → (stilbene)^? → (stilbene)^2?. The observed shift is discussed in a simple VB scheme, particularly in comparison with the results on anthracene negative ions. The resonance Raman effect was striking for both ions with intensity maxima at the exciting wavelengths close to the absorption maxima.     

Photophysical and (photo)electrochemical properties of a coumarin dye

A new coumarin dye, cyano-{5,5-dimethyl-3-[2-(1,1,6,6-tetramethyl-10-oxo-2,3,5,6-tetrahydro-1H,4H,10H-11-oxa-3a-aza-benzo[de]anthracen-9-yl)vinyl]cyclohex-2-enylidene}-acetic acid (NKX-2753), was prepared and characterized with respect to photophysical and electrochemical properties. It was employed as a dye sensitizer in dye-sensitized solar cells and showed efficient photon-to-electron conversion properties. The photocurrent action spectrum exhibited a broad feature with a maximum incident photon-to-electron conversion efficiency (IPCE) of 84% at 540 nm, which is comparable to that for the famous red dye RuL2(NCS)2 (known as N3), where L stands for 2,2'-bipyridyl-4,4'-dicarboxylic acid. The sandwich-type solar cell with NKX-2753, under illumination of full sun (AM1.5, 100 mW cm(-2)), produced 16.1 mA cm(-2) of short-circuit photocurrent, 0.60 V of open-circuit photovoltage, and 0.69 of fill factor, corresponding to 6.7% of overall energy conversion efficiency using 0.1 M LiI, 0.05 M I2, 0.1 M guanidinium thiocyanate, and 0.6 M 1,2-dimethyl-3-n-propyl-imidazolium iodide in dry acetonitrile as redox electrolyte. In comparison with its analogue NKX-2586 (Langmuir 2004, 20, 4205), NKX-2753 with an extra side ring on the alkene chain produced much higher IPCE values at the same conditions. The side ring acted as a spacer to efficiently prevent dye aggregation when adsorbed on the TiO2 surface, resulting in significant improvements of short-circuit photocurrent, open-circuit photovoltage, and fill factor compared with NKX-2586 that aggregated on the TiO2 surface.     

Adsorption and reactions of NO on clean and CO-precovered Ir(111)

Adsorption and reactions of NO on clean and CO-precovered Ir(111) were investigated by means of X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HR-EELS), infrared reflection absorption spectroscopy (IRAS), and temperature-programmed desorption (TPD). Two NO adsorption states, indicative of fcc-hollow sites and atop sites, were present on the Ir(111) surface at saturation coverage. NO adsorbed on hollow sites dissociated to Na and Oa at temperatures above 283 K. The dissociated Na desorbed to form N2 by recombination of Na at 574 K and by a disproportionation reaction between atop-NO and Na at 471 K. Preadsorbed CO inhibited the adsorption of NO on atop sites, whereas adsorption on hollow sites was not affected by the coexistence of CO. The adsorbed CO reacted with dissociated Oa and desorbed as CO2 at 574 K.     

Thermal behavior of ternary Sm2Fe17Nx magnets

The Mössbauer spectra of Sm₂Fe₁₇N_x, prepared by the nitrogenation of Sm₂Fe₁₇ powders in an ammonia and hydrogen atmosphere, were observed at elevated temperatures to shed light on the thermal behavior of nitrogen in the compounds Sm₂Fe₁₇N_x. It was found that there were large differences in thermal behavior between the starting Sm₂Fe₁₇, crystalline Sm₂Fe₁₇N_x (x≈1.7) and amorphous Sm₂Fe₁₇N_x(x～7). The thermal decomposition behavior of Sm₂Fe₁₇N_3.2, developed as one of the most promising hard magnetic materials, was found to be different under different atmospheres.     

Phototoxic process after rapid photosensitive membrane damage of 5,5"-bis(aminomethyl)-2,2':5',2"-terthiophene dihydrochloride

We report a new aspect of rapid (<30 s) light-induced cell membrane damage photosensitized by 5,5"-bis(aminomethyl)-2,2':5',2"-terthiophene dihydrochloride (BAT), which is a water-soluble alpha-terthienyl analogue, using a high-power laser (light intensity 1.6 W cm(-2)). In this paper, we will discuss the relationship between the exposure time of the cells to the photosensitizer and the phototoxic process. Three toxic processes can be identified: first, a non-light-mediated toxicity dependent on BAT-cell incubation; second, a phototoxicity independent of BAT exposure time when the BAT concentration is in the 2-10-microM range; third, a phototoxicity dependent on BAT exposure time when BAT concentration becomes 20 microM. The cytotoxicity decreases when alpha-tocopherol, an antioxidant, is added to a cell membrane. This pattern of phototoxicity is the typical of a phospholipid peroxidation chain reaction and oxidative damage of membrane proteins triggered by a reactive oxygen species generated by a triplet state of BAT. The BAT exposure time is clearly correlated with the partition of the photosensitizer in the cell membrane and inside the cell.