Peralkylated-beta-cyclodextrin used as gas chromatographic stationary phase prepared by sol-gel technology for capillary column

For the first time, three peralkylated-beta-cyclodextrins (beta-CD), permethylated-beta-CD, perethylated-beta-CD and perpentylated-beta-CD, were coated onto the fused-silica capillary by sol-gel method with simplicity and rapidity. Multiple steps in conventional column preparation technology were avoided. Also, these new columns demonstrated many inherent advantages, the main being the outstanding thermal stability (up to 300 degrees C), high number of theoretical plates, excellent column-to-column and run-to-run reproducibility, and pronounced selectivity for positional isomers and enantiomers. Using n-tridecane as a test reagent (k = 4.18), an efficiency value of 3520 theoretical plates/m was obtained on a sol-gel perpentylated-beta-CD capillary column (15 m x 0.25 mm I.D.). On the basis of the results, we proposed that the peralkylated-beta-CD, which has no terminal hydroxyl group, is encapsulated in the sol-gel network and the whole matrix is chemically bonded to the surface of the fused-silica tubing.     

Arylmethyl radicals from arylmethoxybromodiazirines

[reaction: see text] Photolytic decompositions of 3-arylmethoxy-3-bromodiazirines afford arylmethyl radicals by homolyses of the diazirines' excited states.     

Synthesis of extremely stable blue light emitting poly(spirobifluorene)s with Suzuki polycondensation

[reaction: see text] Full spirobifluorene-based blue light emitting polymers, which exhibited extraordinary thermal and color stability, were prepared with SPC through an AB-type monomer route.     

Continuous medium theory for nonequilibrium solvation: II. Interaction energy between solute charge and reaction field and single-sphere model for spectral shift

On the basis of continuous medium theory, a model for evaluation of spectral shifts in solution has been developed in this work. The interaction energy between solute dipole and reaction field and the self-energy of the reaction field have been formulated through derivations. Applying the interaction energy expression together with the point dipole approximation to the case of spherical cavity produces new formulations of spectral shifts. The same expression of electrostatic free energy of the nonequilibrium state is achieved by integrating the change of the electrostatic free energy for a charging process. Moreover, generalized formulations evaluating spectral shifts have been established in the charge-potential notation, and the reduction of them to the point dipole case consistently leads to the same formulations of spectral shifts as those by interaction energy approach. Mutual supports provide convincing evidences for the reliability of the present results. In this work, attentions are particularly paid to the conclusion of zero self-energy of the reaction field, which is different from the previous theory. Reasoning and arguments are given on this point. From the present derivations, it is concluded that the spectral shifts of light absorption and emission were theoretically exaggerated in the past, in particular, by a factor of 2 for the spectral shift sum.     

First results from KamLAND: evidence for reactor antineutrino disappearance

KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.     

Ferroelectricity in barium titanate quantum dots and wires

Properties of BaTiO3 colloidal quantum dots and wires are simulated using a first-principles-based approach. Large atomic off-center displacements (that are robust against capping matrix materials) are found to exist in very small (<5 nm) dots. We further determine the size dependences of electrical and electromechanical responses in the studied nanostructures, as well as provide microscopic understanding of these responses.     

First-principles determination of electromechanical responses of solids under finite electric fields

We describe a first-principles, easy-to-implement, and efficient approach for determining the structural geometry of insulating solids under finite electric fields. This method consists of simultaneously minimizing the field-induced total ionic forces and the electric free energy. Moreover, we present a theory to analyze its predictions that provides a microscopic understanding of electro-mechanical responses in materials. We illustrate this approach by computing piezoelectric and dielectric responses of two rather different compounds, namely, ferroelectric PbTiO3 and semiconductor GaN.     

Electronic stability of magnetic Fe/Co superlattices with monatomic layer alternation

We report a surprising observation that the growth of the [Fe(1 ML)/Co(1 ML)](n) superlattice of L1(0) structure on Cu(100) is stable only up to six atomic layers (n=3), which cannot be rationalized by stress arguments. Instead, first-principles calculations reveal a transition from the L1(0) to the B2 structure due to the effect of dimensionality on the stability of the electronic structure of the superlattice. Whereas the majority-spin electrons are energetically insensitive to the layer thickness, the minority-spin electrons induce the transition at n=3.     

Ordered mesoporous organic-inorganic hybrid materials containing microporous functional calix[8]arene amides

Ordered mesoporous organic-inorganic hybrid materials containing microporous functional calix[8]arene amides have been synthesized and characterized for the first time, and are shown to be effective in removal of trace humic acid contaminant from water.     

Catalytic enantioselective allylation with chiral Lewis bases

The advent of chiral Lewis base-promoted allylation of aldehydes has opened a new direction in the catalytic enantioselective construction of homoallylic alcohols. This short review outlines the conceptual framework for the creation of this new process and the interplay of mechanistic investigations and synthetic studies that have conspired to produce a useful new reaction. The current state-of-the-art in catalyst design and application of the reaction in synthesis are briefly illustrated.