Solid-state photoelectron transfer in powdery nanocomposites comprised of a sensitiser, photoacid generators and silica nanoparticles

The dry beads milling of a mixture of 9,10-dipropoxyanthracene (DPA) as an electron donor and surface-modified silica nanoparticles was conducted in the absence or in the presence of a photoacid generator (PAG) as an electron acceptor to give powdery nanocomposites. Fluorescence measurements indicated no mechanochemical change in the crystal structure of DPA after the nanohybridisation. The co-milling with PAG resulted in solid-state fluorescence quenching, whereas quenching efficiency was considerably dependent on the nature of PAG. The solid-state sensitised photoacid generation through the electron transfer was demonstrated by the solid-state photocolouration of leuco-dye of crystal violet lactone.     

Microenvironment array chip for cell culture environment screening

We have developed a microarray of cell culture environments composed of a combination of soluble factors and extracellular matrices for screening of cell culture environment.     

Catch and release of alkyne-tagged molecules in water by a polymer-supported cobalt complex

A cobalt-phosphine complex supported on PS-PEG beads was found to react with a propargyl carbamate tag, and the tagged molecules immobilized on the beads could be released by acidic treatment through the Nicholas reaction pathway. These reactions work in aqueous media at 4 °C, so that this catch and release procedure is compatible with conditions generally used in biochemical experiments.     

Ring cleavage and successive aldol reaction of 3-[(trialkylsilyl)methyl]cyclobutanones

3-[(Trialkylsilyl)methyl]cyclobutanones reacted with aldehydes by activation with titanium(IV) chloride to give acyclic β,γ-unsaturated β'-hydroxyketones.     

Silver-mediated trifluoromethoxylation of aryl stannanes and arylboronic acids

A silver-mediated cross-coupling of trifluoromethoxide with aryl stannanes and arylboronic acids to give aryl trifluoromethyl ethers is reported. This is the first report of a transition-metal-mediated C(aryl)-OCF(3) bond formation.     

Highly Z-selective asymmetric 1,4-addition reaction of 5H-oxazol-4-ones with alkynyl carbonyl compounds catalyzed by chiral guanidines

An asymmetric 1,4-addition reaction of 5H-oxazol-4-ones with alkynyl carbonyl compounds was developed, and, for the first time, high enantiomeric and geometric control was achieved to afford the thermodynamically unstable Z-isomer predominantly using chiral guanidine catalysts bearing a hydroxy group at the appropriate position. The method provides synthetically useful γ-butenolide ester bearing a chiral quaternary stereogenic center.     

Experimental evidences for molecular origin of low-Q peak in neutron/x-ray scattering of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ionic liquids

Short- and long-range liquid structures of [C(n)mIm(+)][TFSA(-)] with n = 2, 4, 6, 8, 10, and 12 have been studied by high-energy x-ray diffraction (HEXRD) and small-angle neutron scattering (SANS) experiments with the aid of MD simulations. Observed x-ray structure factor, S(Q), for the ionic liquids with the alkyl-chain length n > 6 exhibited a characteristic peak in the low-Q range of 0.2-0.4 A?(-1), indicating the heterogeneity of their ionic liquids. SANS profiles I(H)(Q) and I(D)(Q) for the normal and the alkyl group deuterated ionic liquids, respectively, showed significant peaks for n = 10 and 12 without no form factor component for large spherical or spheroidal aggregates like micelles in solution. The peaks for n = 10 and 12 evidently disappeared in the difference SANS profiles ΔI(Q) [=I(D)(Q) - I(H)(Q)], although that for n = 12 slightly remained. This suggests that the long-range correlations originated from the alkyl groups hardly contribute to the low-Q peak intensity in SANS. To reveal molecular origin of the low-Q peak, we introduce here a new function; x-ray structure factor intensity at a given Q as a function of r, S(Q) (peak)(r). The S(Q) (peak)(r) function suggests that the observed low-Q peak intensity depending on n is originated from liquid structures at two r-region of 5-8 and 8-15 A? for all ionic liquids examined except for n = 12. Atomistic MD simulations are consistent with the HEXRD and SANS experiments, and then we discussed the relationship between both variations of low-Q peak and real-space structure with lengthening the alkyl group of the C(n)mIm.     

Synthesis, crystal structures and photoluminescence properties of new oxyborates, Mg5NbO3(BO3)3 and Mg5TaO3(BO3)3, with novel warwickite-type superstructures

Single crystals of new oxyborates, Mg₅NbO₃(BO₃)₃ and Mg₅TaO₃(BO₃)₃, were prepared at 1370 °C in air using B₂O₃ as a flux. They were colorless and transparent with block shapes. X-ray diffraction analysis of the single crystals revealed Mg₅NbO₃(BO₃)₃ and Mg₅TaO₃(BO₃)₃ to be isostructural. The X-ray diffraction reflections were indexed to the orthorhombic Pnma (No. 62) system with a=9.3682(3) Å, b=9.4344(2) Å, c=9.3379(3) Å and Z=4 for Mg₅NbO₃(BO₃)₃ and a=9.3702(3) Å, b=9.4415(3) Å, c=9.3301(2) Å and Z=4 for Mg₅TaO₃(BO₃)₃. The crystal structures of Mg₅NbO₃(BO₃)₃ and Mg₅TaO₃(BO₃)₃ are novel warwickite-type superstructures having ordered arrangements of Mg and Nb/Ta atoms. Polycrystals of Mg₅NbO₃(BO₃)₃ prepared by solid state reaction at 1200 °C in air showed broad blue-to-green emission with a peak wavelength of 470 nm under 270 nm ultraviolet excitation at room temperature.     

The decoupling of defective linear dynamical systems in free motion

It was demonstrated in two earlier papers that there exists a real, linear, time-varying transformation that decouples any non-defective linear dynamical system in free vibration in the configuration space. As an extension of this work, the present paper represents the first systematic effort to decouple defective systems. It is shown that the decoupling of defective systems is a rather delicate procedure that depends on the multiplicities of the system eigenvalues. While any defective system can be decoupled with the eigenvalues kept invariant, the geometric multiplicities of these eigenvalues may not be preserved. Several numerical examples are provided to illustrate the theoretical developments.