Total synthesis of dl-hop ether,an iridoid monoterpene

An iridoid monoterpene hop ether, 2,2-dimethyl-6-methylene-3-oxabicyclo[3.3.0]octane, was first synthesized in six steps starting from the protected lactol form of 3-formyl-2-methoxy-carbonylcyclopentanol.     

Extensive quinoidal oligothiophenes with dicyanomethylene groups at terminal positions as highly amphoteric redox molecules

A series of highly extensive quinoidal oligothiophenes carrying a dicyanomethylene group at both terminal positions is synthesized. As the quinoidal structures extend, they have highly amphoteric abilities and show strong electronic absorptions in the visible to near-infrared region. The higher homologues, quinquethiophene and sexithiophene, exist as equilibrium mixtures with the biradical species.     

Structural determination of carnosadine,a new cyclopropyl amino acid,from red alga Grateloupia carnosa

A new cyclopropyl amino acid, carnosadine, was isolated from red alga Grateloupia carnosa and the structure was determined to be 1-amino-2-guanidino-methylcylopropane-1-carboxylic acid from the results of NMR, mass spectrometry and coloring tests.     

Vacuum ultraviolet photolysis of CClF2CH2Cl

Photolysis of CClF₂CH₂Cl was studied by 147 nm vacuum ultraviolet irradiation. In the presence of NO; CF₂CH₂, CF₂CHCl, and CClF₂CN were produced. These products represent three different reaction paths; the molecular dechlorination, molecular dehydrochlorination, and chlorine radical elimination reactions. The reactant pressure and the addition gas (He or NO) pressure effects upon the product yield were studied. © 1994 John Wiley & Sons, Inc.     

Turbulent diffusion for the radial twist map

An analytical tool is given to study the statistical properties of the radial twist map, X_n+1 = X_n + α(Y_n+1) and Y_n+1 = Y_n + Af (X_n), with arbitrary rotation number α(Y) and arbitrary periodic force f(X). The case for which f(X) = sin 2 πX and with arbitrary α is treated in the region of large A. The turbulent diffusion coefficient D for the chaotic orbit relaxes as $\text{t}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$ to $\text{A}{}^2\text{4}$, except for the case of the standard map, where the eventual value of D is different from $\text{A}{}^2\text{4}$.     

Tunable design strategy for fluorescence probes based on 4-substituted BODIPY chromophore: improvement of highly sensitive fluorescence probe for nitric oxide

4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) is a well-known fluorophore, with a high molar extinction coefficient and high fluorescence quantum efficiency (Phi(fl)). Furthermore, its structure can be modified to change its excitation and emission wavelengths. However, little work has been done on the structural modification of fluorines at the B-4 position with other functional groups. We synthesized 4-methoxy-substituted BODIPY derivatives in satisfactory yields, and found that they exhibited improved solubility in aqueous solution. Moreover, their oxidation and reduction potentials were greatly decreased without any change in their absorbance and fluorescence properties. These features of 4-substituted BODIPYs may be useful for developing novel fluorescence probes based on the intramolecular photoinduced electron transfer (PeT) mechanism, because it is possible to optimize the PeT process precisely by modulating the electrochemical properties of the fluorophore. The value of this approach is exemplified by its application to the development of a highly sensitive and pH-independent fluorescence probe for nitric oxide.     

Preparation of Y2O3:Eu thin films by excimer-laser-assisted metal organic deposition

Europium-doped yttrium oxide (Y₂O₃:Eu) thin films were successfully deposited on quartz and ITO/glass substrates by excimer-laser-assisted metal organic deposition (ELAMOD) at low temperatures. The effects of laser wavelength and thermal temperature on the films’ crystallinity and photoluminescence properties were investigated. Films irradiated by an ArF laser at 80 mJ/cm² and 400–500°C were highly crystallized compared with those prepared by thermal MOD. In contrast, when the film was irradiated by a KrF laser at 500°C, no crystalline Y₂O₃:Eu was formed. The Y₂O₃:Eu film irradiated by the ArF laser at 80 mJ/cm² and 500°C showed typical PL spectra of Eu³⁺ ions with cubic symmetry and a ⁵D₀→⁷F₂ transition at ∼612 nm. The PL intensity at 612 nm was much higher for the film prepared with ELAMOD than for that prepared by the thermal-assisted process, and the photoemission intensity of the film prepared with ELAMOD strongly depended on the substrate material.