Synthesis and magnetic properties of InM2+CrS4(M2+ = Mn,Fe,Co, Ni)

The crystallographic and magnetic properties of the compounds InM²⁺CrS₄(M = Mn, Fe, Co, Ni) were studied. Three of these compounds except MnInCrS₄ were antiferromagnetic. The Néel termperature and paramagnetic Curie temperature were determined to be 20 and 82K for InFeCrS₄, 36 and 115K for InCoCrS₄ and 22 and 26K for InNiCrS₄, respectively.     

Lobohedleolide and (7Z)-lobohedleolide,new cembranolides from the soft coral lobophytum hedleyi whitelegge

The structures of lobohedleolide (1) and (7Z)-lobohedleolide (2), two new cembranolides containing the α,β-unsaturated carboxylic acid system isolated from the Japanese soft coral Lobophytum hedleyi Whitelegge, were elucidated from spectral and chemical evidence, and the absolute configuration of (1) was determined by X-ray analysis of its p-bromophenacyl ester (9). Lobohedleolide (1) showed growth inhibition of the in vitro Hella cells.     

(Studies on AI-77s,microbial products with pharmacological activity) structures and the chemical nature of AI-77s

The structures of a novel gastroprotective substance AI-77-B and its analogues AI-77-C, D, F and G, which are produced by Bacillus pumilus, are described. Five of the asymmetric centers of AI-77-B have S absolute stereochemistry confirmed by X-ray in combination with chemical studies.     

Optically detected electron—nuclear double resonance and electron—nuclear—nuclear triple resonance study of 17O hyperfine coupling in the lowest nπ* triplet state of benzil

Optically detected ENDOR and electron—nuclear—nuclear triple resonance of ¹⁷O were measured via phosphorescence from ³(nπ^*) benzil in benzophenone-d₁₀ crystals at high magnetic field. The n and π^* spin densities on the oxygen atom are 0.201 and 0.092, respectively, the angle between the two CO bonds being 150°.     

Adlayer of hydroquinone on Pt(111) in solution and in a vacuum studied by STM and LEED

Hydroquinone (HQ) adlayers were formed on Pt(111) in HF solution and in a vacuum. By using scanning tunneling microscopy (STM) in solution, it was revealed that HQ formed an ordered structure on Pt(111) with a strong attractive interaction between two adjacent hydroxyl groups in neighboring HQ molecules. After the sample was transferred into a vacuum, low-energy electron diffraction (LEED) measurement was performed, which showed that the (2.56 x 2.56)R16 degrees incommensurate structure of the HQ adlayer was formed in solution. The HQ adlayer on Pt(111) was formed also by vapor deposition, and the identical (2.56 x 2.56)R16 degrees adlayer structure was found by LEED and STM in a vacuum.     

Application of high pressure induced by water-freezing to the direct catalytic asymmetric three-component List-Barbas-Mannich reaction

High pressure induced by water-freezing has been successfully applied to the direct catalytic asymmetric-three component List-Barbas-Mannich reaction, in which higher yield and better enantioselectivity can be realized than those from the reaction at room temperature under 0.1 MPa.     

Practical optical frequency measurement system around 1.5 μm based on an acetylene-stabilized laser-locked optical frequency comb

We have developed a practical and precise frequency measurement system at 1.5 μm telecommunication band. An electro-optic-modulator based optical frequency comb is phase-locked to a dither-free acetylene-stabilized laser to realize an optical frequency comb with frequency uncertainty of 10 kHz (5 × 10⁻¹¹) and the linewidth of 15 kHz. The present frequency comb can be also used as an optical frequency reference grid defined by ITU-T (International Telecommunication Union, Telecommunication Standardization Sector). Using the present frequency measurement system, we have demonstrated the first optical frequency measurement of ¹²C¹⁶O overtone absorption lines around 1.56 μm with the uncertainty of lower than 900 kHz.