TfOH-promoted transformation from 2-alkynylphenyl isothiocyanates to quinoline-2-thiones or indoles

A variety of 4-arylquinoline-2-thiones and 3-arylthieno[2,3-b]indoles were synthesized in high yields via TfOH-promoted tandem Friedel-Crafts alkenylation-cyclization reactions of 2-alkynylphenyl isothiocyanates.     

Adsorption and dissociation of water on LaB6(100) investigated by surface vibrational spectroscopy

The chemisorption of water (H₂O and D₂O) on a LaB₆(100) surface was studied with reflection absorption infrared spectroscopy (RAIRS) and high resolution electron energy loss spectroscopy (HREELS). The clean surface was exposed to H₂O and D₂O at temperatures from 90 K to room temperature, and spectra were acquired after heating to temperatures as high as 1200 K. It was found that water molecularly adsorbs on the surface at 90 K as a monomer at low coverages and as amorphous solid water at higher coverages. Water adsorbs dissociatively at room temperature to produce surface hydroxyl species as indicated by OH/OD stretch peaks at 3676/2701 cm^?1. Room temperature adsorption also reveals low frequency loss features in HREEL spectra near 300 cm^?1 that are quite similar to results obtained following the dissociative adsorption of O₂. In the latter case, the loss features were attributed to the LaO stretch of O atoms bridge-bonded between two La atoms. In the case of dissociative adsorption of H₂O, the low frequency loss features could be due to either the LaO vibrations of adsorbed O or of adsorbed OH.     

Visible-light-triggered release of nitric oxide from N-pyramidal nitrosamines

Although many organic/inorganic compounds that release nitric oxide (NO) upon photoirradiation (phototriggered caged-NOs) have been reported, their photoabsorption wavelengths mostly lie in the UV region, because X-NO bonds (X=heteroatom and metal) generally have rather strong π-bond character. Thus, it is intrinsically difficult to generate organic compounds that release NO under visible light irradiation. Herein, the structures and properties of N-pyramidal nitrosamine derivatives of 7-azabicyclo[2.2.1]heptanes that release NO under visible light irradiation are described. Bathochromic shifts of the absorptions of these nitrosamines, attributed to HOMO (n)-LUMO (π*) transitions associated with the nonplanar structure of the N-NO moiety, enable the molecules to absorb visible light, which results in N-NO bond cleavage. Thus, these compounds are innate organic caged-NOs that are uncaged by visible light.     

Secondary structure of homo-thiopeptides based on a bridged β-proline analogue: preferred formation of extended strand structures with trans-thioamide bonds

Homo-thiopeptides of bicyclic 7-azabicyclo[2.2.1]heptane-2-endo-carboxylic acid (Ah2c), which is a conformationally constrained β-proline mimic, were synthesized and their structures were investigated. These homo-thiopeptides showed a preference for ordered secondary structures with trans-thioamide bonds in the solid state and in solution.     

The Influences of the Magnetic Field Strength on the Magnetic Confinement of Primary Electrons in an Ion Source

This paper deals with the simulation of trajectories of energetic electrons under the influence of a multi-cusp magnetic field produced by a permanent magnet assembly in a ring cusp geometry which is designed for supporting a plasma based ion source. The primary electrons are assumed as being emitted from a cathode located coaxially with the cylindrical discharge chamber. The volume of the region occupied by the electron trajectories and the magnetic trapping time were evaluated and plots are presented showing the effects of the surface magnetic field strength of the magnets on the volume and the mean confinement time of primary electrons in the ion source.     

Measurement of the degree of polarisation of thermally modified Scots pine using a Stokes imaging polarimeter

Optical Review - This study measured the polarised light reflected from the surface of thermally modified Scots pine (Pinus sylvestris L.) wood using a Stokes imaging polarimeter. The data were...     

Fluorescence Response and Self-Assembly of a Tweezer-Type Synthetic Receptor Triggered by Complexation with Heme and Its Catabolites

There is increasing interest in the development and applications of synthetic receptors that recognize target biomolecules in aqueous media. We have developed a new tweezer-type synthetic receptor that gives a significant fluorescence response upon complexation with heme in aqueous solution at pH 7.4. The synthetic receptor consists of a tweezer-type heme recognition site and sulfo-Cy5 as a hydrophilic fluorophore. The receptor–heme complex exhibits a supramolecular amphiphilic character that facilitates the formation of self-assembled aggregates, and both the tweezer moiety and the sulfo-Cy5 moiety are important for this property. The synthetic receptor also exhibits significant fluorescence responses to biliverdin and bilirubin, but shows very weak fluorescence responses to flavin mononucleotide, folic acid, and nicotinamide adenine dinucleotide, which contain smaller π-scaffolds.     

Variation of Microenvironment around Auramine O Molecules Doped in Silica Prepared from Tetramethoxysilane

Silica gel doped with Auramine O (AuO), which is known as a microscopic viscosity probe through fluorescence spectra, was prepared by the sol-gel method using tetramethoxysilane (TMOS) as a starting alkoxide. Fluorescence spectra from the starting solution to the dry gel were measured to pursue the variation of microscopic viscosity around the AuO molecules during the sol-gel process. The fluorescence intensity of AuO did not change at the gelation point, indicating that the microscopic viscosity around AuO did not change during the sol-to-gel transformation. The intensity was, however, increased largely in the drying process; the internal motion of AuO molecules became largely restricted by the surrounded silica matrix during the drying process.