Target-selective fluorescent "switch-on" protein labeling by 6π-azaelectrocyclization

Application of azaelectrocyclization and FRET techniques to lysine groups enabled the selective and sensitive detection of a target protein from a mixture, with high fluorescence contrast.     

Structural and spectroscopic characterization of a diruthenium o-dioxolene complex possessing a singly occupied molecular orbital delocalized over the entire molecule, [Ru2(3,6-DTBDiox)4]-

Chemical oxidation of [Ru2(6+)(3,6-DTBCat)4]2- affords [n-Bu4N][Ru2(3,6-DTBDiox)4].acetone (2.acetone). The oxidized species was characterized by X-ray crystallographic analysis and EPR, and the delocalization of the unpaired electron over the entire molecule was indicated. This example showed that the utilization of redox-active ligands into a Ru2 complex expanded the degree of freedom in the electronic structure. DFT calculations support this view, and the spin population was estimated to be approximately 18% and 82% for the Ru2 core and the four dioxolene ligands, respectively.     

HeII(304Å) photoelectron spectrum of N2O4

The 304 Å HeII photoelectron (PE) spectrum of a mixture of NO₂ and N₂O₄ in the gaseous phase has been measured in the region up to 29 eV. By subtracting the HeII spectrum of NO₂ from the mixed spectrum, the HeII spectrum due to N₂O₄ has been deduced, indicating that there are three new PE bands in the region 20—29 eV. Relative band intensities have also been obtained from the HeII of N₂O₄ below 16 eV, corrected for electron collecting efficiency.     

Construction of nitrogen-heterocyclic compounds through zirconium mediated intramolecular alkene-carbonyl coupling reaction of N-(o-alkenylaryl)carbamate derivatives

Intramolecular alkene-carbonyl coupling reaction of N-benzyl-N-(o-alkenylaryl)carbamate derivative derived from o-aminostyrene, o-(aminomethyl)styrene and o-aminoallylbenzene smoothly proceeded by treating with zirconocene-butene complex to give the corresponding lactam derivative.     

Remarkably Selective Ag(+) Extraction and Transport by Thiolariat Ethers

Synthesis and metal binding properties of thiolariat ethers, where a sulfide side chain is introduced into a framework of a crown ether, have been performed. Remarkably high Ag(+) selectivity among heavy metal ions was observed in solvent extraction and transport across a liquid membrane using thiolariat ethers with a 15-crown-5 ring as carriers. Thiolariat ethers with a 12-crown-4 or a 18-crown-6 do not exhibit such a high Ag(+) selectivity. The former binds metal ions weakly, and the latter recognizes Pb(2+) as well as Ag(+). The corresponding oxygen analogs, i.e. lariat ethers, do not show Ag(+) selectivity. The Ag(+) binding strength of the sulfoxide and sulfone analogs is much lower than that of thiolariat ethers. Thiolariat ethers with a benzocrown framework containing a sulfide chain at the 4 position of the benzene nucleus showed very low affinity to Ag(+). Extractability and transport ability using various thiolariat ether derivatives strongly suggested that this high Ag(+) selectivity is a result of the synergistic coordination of the ring oxygen and the sulfur atom of the thiolariat ether. NMR chemical shifts of protons and carbons in the proximity of the sulfur atom of the thiolariat ether were changed significantly in accordance with the synergistic coordination described above. 1:1 Complexation between a thiolariat ether and Ag(+) were supported by a Job plot using the chemical shift of the methylene protons adjacent to the sulfur atom.     

Photoelectron spectroscopic study of simple hydrogen-bonded dimers. I. Supersonic nozzle beam photoelectron spectrometer and the formic-acid dimer

In this paper we describe several characteristics of our supersonic nozzle beam photoelectron spectrometer recently constructed for studying hydrogen-bonded dimers in the gas phase by HeI (58.4 nm) radiation. Using this photoelectron apparatus, we have reinvestigated the HeI photoelectron spectrum of the formic-acid dimer (HCOOH)₂ which is well known as a fairly strong doubly hydrogen-bonded dimer. It was found that the (HCOOH)₂ spectrum deduced here from the spectrum of the monomer—dimer mixture considerably differs from that reported by Carnovale et al. in the region beyond 16.5 eV. New spectral assignments are given for four ionization bands beyond 16.5 eV. It is also indicated that the lower bound of the dissociation energy of (HCOOH)₂⁺ is estimated to be 1.0 ± 0.1 eV from the threshold of the dimer band (11.0 eV) obtained in this experiment. This value is considerably smaller than the value of 1.7 ± 0.2 eV recently reported for the water dimer cation (H₂O)₂⁺.     

Educational equipment in the periphery of a large computer

Two practical examples of educational equipment in the periphery of a large (or medium) computer are described. The management system for lessons with several video displays is illustrated by a flow chart, and the total load to the central processor is assessed. A demonstration equipment which combines a graphic display, a scan-converter and a projection TV, is shown to be valuable. Possibilities of improvement are indicated.     

Photochromism of single crystals composed of dioxazolylethene and dithiazolylethene

Although dioxazolylethene 1a did not show any photocoloration in the single crystalline phase, 1a displayed photochromism in the mixed crystal containing both 1a and dithiazolylethene 2a ; the mixed crystal changed color from colorless to red, orange, and yellow upon irradiation with light of appropriate wavelengths.