Sensing of ozone based on its quenching effect on the photoluminescence of CdSe-based core-shell quantum dots

Microchimica Acta - Thin films of CdSe-based core-shell type quantum dots (CdSe/CdZnS, CdSe/ZnS and CdSeTe/ZnS) deposited on glass substrate were found to undergo a reversible change in...     

Synthesis of Multisubstituted Olefins through Regio‐ and Stereoselective Addition of Interelement Compounds Having B–Si,B–B,and Cl–S Bonds to Alkynes,and Subsequent Cross‐Couplings

Multisubstituted olefins are fundamental motifs in organic compounds. In this account, we describe the synthesis of organic molecules bearing an olefinic moiety by the transition‐metal‐catalyzed regio‐ and stereoselective addition of a variety of interelement compounds to alkynes. Regio‐ and stereoselective silaboration, diborylation, and chlorothiolation have been achieved by using the transition‐metal catalysts. The subsequent cross‐coupling reactions of the boron‐containing alkenes to install various aryl groups afforded the corresponding tri‐ and tetraarylated olefins. This account describes our research on the highly regio‐ and stereoselective synthesis of multifunctionalized olefins such as tetraarylethenes with four different aryl groups.

     

The alignment of nematic liquid crystals on photolithographic micro-groove patterns

Abstract

The alignment of nematic liquid crystals on micro-groove patterns was studied. It has been found that the order of the alignments is determined by the edge shape, spacing, and line pitch of the micro-groove patterns. On coarse patterns, with pitches greater than 2 μm, striped patterns of the liquid crystal alignment were observed using polarized light which manifested different orientations of the liquid crystals on the top, edge, and bottom of the grooves, respectively. On fine patterns, with pitches less than 2 μm, a uniform device-quality alignment has been realized, with which twisted nematic cells were constructed in combination with the rubbed alignment layer on the opposite substrate. Their viewing angle characteristics and tilt orientations of the director were also investigated.     

Synthesis of β, γ-Unsaturated Valerolactones

In recent years various attempts have been made to use reagent equivalents¹) in order to effect reactions which are not otherwise accessible by means of conventional reagents. Particularly it is to be noted that synthetic equivalents for unreactive dienophiles, such as carbon dioxide,^2,3,4) ketene,^3,5) allene,⁶⁾ and acetylene,⁷⁾ have greatly extended the scope of the cycloaddition reactions into systems not normally generated by the thermal process.