Fluorescence Turn‐On Sensing of Lectins with Mannose‐Substituted Tetraphenylethenes Based on Aggregation‐Induced Emission

The synthesis of mannose‐substituted tetraphenylethenes (TPEs) and their aggregation‐induced emission (AIE) behavior, induced by interactions with concanavalin A (Con A), are reported. A mixture of the mannose‐TPE conjugates and Con A in a buffer solution displays an intense blue emission on agglutination within a few seconds, which serves as a “turn‐on” fluorescent sensor for lectins. The sensing is also selective: the conjugates act as a sensor for Con A, but do not sense a galactose‐binding lectin, PNA. Con A‐recognition is not affected even in the presence of other proteins in a mixture. The conjugates also exhibit high sensitivity to detect Con A. An increased sensitivity of the conjugates results if mannopyranoside substituents are linked to the TPE‐core unit with a flexible chain and/or when the number of mannose residues increases.     

On the Intramolecular Interactions of Si/P in 1,2‐Phenylene Frameworks

The synthesis and structure of 1‐diphenylphosphino‐2‐(fluorodiphenylsilyl) benzene 1 and 1‐diphenylphosphino‐2‐(difluorophenylsilyl)‐ benzene 2 are reported. An X‐ray crystal structure analysis of 1 shows a weak interaction between the silicon and phosphorus moieties, producing a hypervalent state at the silicon. The hypervalent state of the silicon is also supported by a natural bond orbital calculation. However, despite having a difluorosilyl group, 2 does not show a hypervalent state for the silicon, based on an X‐ray crystal structure analysis. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 00:1–5, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21044     

Dependence of lasing threshold power on excitation wavelength in dye-doped cholesteric liquid crystals

Relationship between threshold power and excitation wavelength has been investigated in distributed feedback (DFB) lasers using dye-doped cholesteric liquid crystals (CLCs). We found that the threshold shows strong dependence on the excitation wavelength. The excitation wavelength was varied over the whole absorption band of a commercial DCM dye, resulting in almost one-order of magnitude lower threshold power by the excitation at the higher energy tail than at the lower energy tail of the absorption band. We confirmed the existence of an optimum wavelength giving the lowest threshold power due to the competition between this effect and decreasing absorption at the higer-energy tail of the absorption band using a different dye, pyromethene 580.     

Rh‐Catalyzed Direct Carboxylation of Alkenyl C−H Bonds of Alkenylpyrazoles

The Rh‐catalyzed direct carboxylation of alkenyl C?H bonds was achieved by using pyrazole as a removable directing group. In the presence of 5 mol% RhCl₃ ? 3H₂O, 6 mol% P(Mes)₃, and 2 equiv. of AlMe₂(OMe), the alkenyl C?H bond of various alkenylpyrazoles was directly carboxylated in good yields under CO₂ atmosphere. Furthermore, several useful transformations of the pyrazole moiety of the product were achieved to afford synthetically useful carboxylic acid derivatives in good yields.     

Analysis of Nitrification in Agricultural Soil and Improvement of Nitrogen Circulation with Autotrophic Ammonia-Oxidizing Bacteria

Accumulations of inorganic nitrogen (NH₄ ⁺, NO₂ ^?, and NO₃ ^?) were analyzed to evaluate the nitrogen circulation activity in 76 agricultural soils. Accumulation of NH₄ ⁺ was observed, and the reaction of NH₄ ⁺?→?NO₂ ^? appeared to be slower than that of NO₂ ^??→?NO₃ ^? in agricultural soil. Two autotrophic and five heterotrophic ammonia-oxidizing bacteria (AOB) were isolated and identified from the soils, and the ammonia-oxidizing activities of the autotrophic AOB were 1.0?×?10³–1.0?×?10⁶ times higher than those of heterotrophic AOB. The relationship between AOB number, soil bacterial number, and ammonia-oxidizing activity was investigated with 30 agricultural soils. The ratio of autotrophic AOB number was 0.00032–0.26 % of the total soil bacterial number. The soil samples rich in autotrophic AOB (>1.0?×?10⁴ cells/g soil) had a high nitrogen circulation activity, and additionally, the nitrogen circulation in the agricultural soil was improved by controlling the autotrophic AOBs.     

Control of luminescence and conductivity of delafossite-type CuYO2 by substitution of rare earth cation (Eu, Tb) and/or Ca cation for Y cation

Delafossite-type oxides of CuTb_yY_1−yO₂, CuEu_yY_1−yO₂, CuCa_xTb_yY_1−x−yO₂ and CuCa_xEu_yY_1−x−yO₂ have been prepared by solid state reactions. The lattice-parameter dependence on the composition implies substitution of the Tb³⁺, Eu³⁺ and Ca²⁺ cations for the Y³⁺ site. Noticeable sharp emission lines due to the f-f transitions (⁵D₄→⁷F_J, J=3-6) of Tb³⁺ or due to the f-f transitions (⁵D₀→⁷F_J, J=0-4) of Eu³⁺ are observed at room temperature. Electrical conductivities of CuCa_xTb_yY_1−x−yO₂ and CuCa_xEu_yY_1−x−yO₂ are larger than those of CuTb_yY_1−yO₂ and CuEu_yY_1−yO₂, indicating the increase of the hole concentration caused by the substitution of Ca²⁺ for the Y³⁺ site. These results indicate the controllability of the luminescence and conductivity in CuCa_xTb_yY_1−x−yO₂ and CuCa_xEu_yY_1−x−yO₂ delafossite-type oxides by simultaneous substitution of the rare earth Tb³⁺ or Eu³⁺ cation and the Ca²⁺ cation for the Y³⁺ site.     

Fabrication of (1 1 1)-oriented Si layers on SiO2 substrates by an aluminum-induced crystallization method and subsequent growth of semiconducting BaSi2 layers for photovoltaic application

We have prepared (1 1 1)-oriented Si layers on SiO₂ (fused silica) substrates from amorphous-Si(a-Si)/Al or Al/a-Si stacked layers using an aluminum-induced crystallization (AIC) method. The X-ray diffraction (XRD) intensity from the (1 1 1) planes of Si was found to depend significantly on growth conditions such as the thicknesses of Si and Al, deposition order (a-Si/Al or Al/a-Si on SiO₂), deposition technique (sputtering or vacuum evaporation) and exposure time of the Al layer to air before the deposition of Si. The crystal orientation of the Si layers was confirmed by θ−2θ, 2θ XRD and electron backscatter diffraction (EBSD). The photoresponse properties of semiconducting BaSi₂ films formed on the (1 1 1)-oriented Si layers by the AIC method were measured at room temperature. Photocurrents were clearly observed for photon energies greater than 1.25 eV. The external quantum efficiencies of the BaSi₂ were also evaluated.     

Induction of optical activity in oligosilanes within the internal cavity of cyclodextrins

The first example of induced optical activity of oligosilanes within the internal cavity of gamma-cyclodextrins is reported.