Decarbonylative cycloaddition of phthalic anhydrides with allenes

The decarbonylative cycloadditions of phthalic anhydrides with allenes were performed by using nickel catalyst. The asymmetric variant of the cycloaddition was also achieved by using chiral phosphine ligands to provide δ-lactones enantioselectively.     

The thermal stabilities of luminescence and microstructures of Eu2+-doped KBaPO4 and NaSrPO4 with β-K2SO4 type structure

Eu(2+)-doped monophosphates NaSrPO(4) and KBaPO(4) with the β-K(2)SO(4) structure were synthesized using the conventional high temperature solid state reaction. The X-ray powder diffraction, photoluminescence excitation, and emission spectra and decay curves were measured. The phosphors can be efficiently excited by UV-visible light from 220 to 430 nm to realize emission in the visible range. The natures of the Eu(2+) emission, e.g., the chromaticity coordinates, the Stokes shifts, and the luminescence absolute quantum efficiencies, were reported. The luminescence quenching temperatures and the thermal activation energies for NaSrPO(4):Eu(2+) and KBaPO(4):Eu(2+) were obtained from the temperature dependent (10-435 K) luminescence intensities and decay curves. KBaPO(4):Eu(2+) presents only one emission center; however, Eu(2+) ions have a "disordered environment" in NaSrPO(4) lattices. The relationship between the luminescence thermal stabilities and the crystal structures was discussed. The crystallographic occupations of rare earth ions doped in these hosts were analyzed by the site-selective emission spectra and the excitation spectra of Eu(3+) ions in the (7)F(0)→(5)D(0) transitions using a pulsed, tunable, and narrow-band dye laser. In KBaPO(4), the Eu(3+) ions could be distributed in the host with a high "ordered state" in only one site in the lattices. However, the multiple site structure of Eu(3+) ions with highly disordered distributions in NaSrPO(4) lattices was suggested.     

Design and synthesis of new chiral phosphorus-olefin bidentate ligands and their use in the rhodium-catalyzed asymmetric addition of organoboroxines to N-sulfonyl imines

Novel chiral phosphorus-olefin bidentate ligands have been synthesized in a few steps from a readily available enantiopure compound. These ligands have been applied to a rhodium-catalyzed asymmetric addition of organoboroxines to N-sulfonyl aldimines, achieving high yield and enantioselectivity.     

Characterization of cross-linking structures in UV-cured acrylic ester resin by MALDI-MS combined with supercritical methanolysis.

The cross-linking structure of the ultra violet (UV)-cured resin prepared from dipentaerithritol hexacrylate (DPHA) was characterized by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with supercritical methanolysis. The MALDI-mass spectrum of the decomposition products obtained by supercritical methanolysis contained a series of peaks of sodium-cationized methyl acrylate (MA) oligomers up to around m/z = 4000 formed through selective cleavage and methylation occurred at ester linkages in UV-cured DPHA. Furthermore, in order to observe widely distributed sequence lengths in the cross-linking junctions, the decomposed products of the cured resin were then fractionated using size exclusion chromatography followed by the MALDI-MS measurements of the individual fractions. The MALDI-mass spectra of the lower molar mass fractions mainly consisted of a series of peaks of MA oligomers around m/z values of several thousands, whereas those of higher molecular weight showed a broad peak up to m/z ca. 180000. The observed distributions of the supercritical methanolysis products suggested that the network junctions in the given UV-cured resin were composed of up to around 2000 acrylate units.     

Grazing-exit and micro X-ray fluorescence analyses for chemical microchips.

Grazing-exit x-ray fluorescence (GE-XRF) and micro x-ray fluorescence (micro-XRF) methods were applied to chemical microchips as a detection method. Since an energy-dispersive x-ray detector was used, the simultaneous detection of multiple elements was possible. An analyzing region was especially designed on the microchip so that a sample solution could be dried and concentrated in a suitable area corresponding to the size of the primary x-ray beam. Finally, it was confirmed that both analytical methods could be combined well for use with a microchip. In GE-XRF, the background intensity in the XRF spectrum was reduced at grazing-exit angles. In addition, a good relationship between the x-ray fluorescence intensities and the concentrations of standard solutions that were introduced into the microchip was obtained. This indicates that the GE-XRF method is feasible for trace elemental analysis in chemical microchip systems. In micro-XRF, an attempt was made to concentrate and dry the analyte within a small analyzing region. The preliminary results indicated that the micro-XRF method could be applied for the analysis of microchips.     

A facile and efficient one-pot synthesis of thiochromans from bis(2-formylphenyl) disulfide and alkenols via iodine-promoted generation and subsequent intramolecular cycloaddition of ortho-thiobenzoquinone methides

Stereoselective synthesis of tetrahydrofuro- and tetrahydropyrano[3,2-c]benzothiopyrans was achieved by intramolecular [4+2]cycloaddition of o-thiobenzoquinone methides that were generated in situ from bis(2-formylphenyl) disulfide and alkenols in the presence of iodine under mild reaction conditions.     

Electrochemically regenerative visible light-induced reactivity of α-Fe2O3 films with Ag(core)–AgCl(shell) microcrystal composites

Ag(core)–AgCl(shell) microcrystal composites (Ag@AgCl) have been formed on an α-Fe₂O₃ film-coated SnO₂ electrode by a 2 step method consisting of the electrochemical reduction of Ag⁺ ions and the subsequent electrochemical oxidation. The synergy of α-Fe₂O₃ and Ag@AgCl gave rise to a high visible light-induced reactivity (λ_ex > 420 nm) for the oxidation of 2-naphthol (2-NAP) used as a model water pollutant in the presence and absence of oxygen. These findings were attributable to the function of Ag@AgCl composites as an excellent charge-separation promoter and built-in acceptor.