Localized open systems in a thermodynamically closed system of chemical reactions

A thermodynamically closed system of chemical reactions becomes unstable against transforming spontaneously a locally planar reaction network into a spherically shaped one if the mean lifetime of the composite two-monomers is greater than the mean collision time of the polymers.     

Ineffective OH Pinning of the Flipping Dynamics of a Spherical Guest within a Tight‐Fitting Tube

A supramolecular/synthetic method has been devised to affix a sterically hindered substituent onto a fullerene guest encapsulated in a tubular host. A two‐wheeled complex of (C₅₉N)‐(C₅₉N) with a tubular host was oxidatively bisected to afford a C₅₉N⁺ cation captured in the tube. The C₅₉N⁺ cation in the tube was then trapped by ethanol or water, which led to an oxy substituent pinned on the guest. The guest motions within the tube were modulated by the pinned substituent, and up‐and‐down flipping motions were halted by an ethoxy substituent. A hydroxy substituent, however, was ineffective in halting the flipping motions, despite the tight‐fitting relationship between the tubular host and the spherical guest. Theoretical calculations of the dynamics revealed that the flipping motions were assisted by OH‐π hydrogen bonds between the guest and the carbon‐rich wall and that sliding motions of the OH group were also facilitated by deformations of the tube.     

Photocleavable molecule for laser desorption ionization mass spectrometry

A new photocleavable molecule for laser desorption ionization mass spectrometry (LDI-MS) was designed and synthesized. The molecule exhibited high sensitivity for negative mode MS detection with good chemical stability. The molecule was successfully applied to molecular tag for (LDI-MS). Kinetic measurement of the amidation reaction and monitoring of aminolysis of acetylated sugars were demonstrated with the molecular tag.     

Synthetic Approach Toward Antibiotic Tunicamycins - VII Synthesis of Tunicamine and Tunicaminyl Uracil Derivative

A higher carbon carbohydrate moiety of antibiotic tunica-mycins named tunicamine has been synthesized in a protected form. The key reaction step of the synthesis is a potassium fluoride catalyzed Henry reaction of a 5-nitroribose derivative and a dial do-galactosamine derivative. The tunicamine derivative has been converted to a tunicaminyl uracil derivative by condenation with bis(trimethylsilyl) uracil.     

Highly Active and Selective Catalysis of Copper Diphosphine Complexes for the Transformation of Carbon Dioxide into Silyl Formate

Copper diphosphine complexes have been found to be highly active and selective homogeneous catalysts for the hydrosilylation of CO₂. The structure of the phosphine ligands strongly affects their catalytic activity. Turnover number (TON) reaches 70 000 after 24 hours with 1,2‐bis(diisopropylphosphino)benzene as a ligand under 1 atmosphere of CO₂. ¹H and ¹³C NMR spectra, carried out under the reaction conditions, showed the reaction mechanism through insertion of CO₂ into Cu? H to afford Cu/formate species.     

Enhancement of the luminescence efficiency of europium(III) tris(β-diketonato) complex in organic media by quaternary ammonium salts with anionic ligands

Benzyldimethyltetradecylammonium (BA14(+)) salts with anionic ligands (X(-)), such as bis(2-ethylhexyl)sulfosuccinate, bis(2-ethylhexyl)phosphate (BEHP(-)), and benzotriazole (BTA(-)) anions, were prepared. These salts were soluble in various organic solvents. The luminescence emission spectra of organic solutions of a red luminescent, tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octadionato)europium(III) complex in the presence of the BA14X's were recorded. The emission intensity of the Eu(III) complex was increased remarkably by the addition of BA14X (X(-) = BEHP(-) and BTA(-)). This effect can be attributed to the formation of 1:1 X(-)-adducts of the Eu(III) complex, in which the asymmetry of the ligand field is increased so as to enhance the emission efficiency of the (5)D(0)→(5)F(2) transition. The enhancement effect by BA14X was higher than that of charge-neutral ligands, such as tri-n-octylphosphine oxide and 1,10-phenanthroline, which have been used as second ligands to enhance the emission efficiency of tris(β-diketonato)europium(III) complexes.     

Inelastic scattering of cosmic ray muons on iron nuclei and the virtual photon shadowing

Hadronic cascade showers originating from inelastic interactions of cosmic ray muons with iron nuclei have been observed in a calorimeter located between two magnetic spectrometers. The separation of those events from the electromagnetic showers has been successfully done in the ranges of the transferred energy v ≳ 50 GeV and its ratio to muon energy v/E ≳ 0,1, by utilizing the difference of their longitudinal cascade developments. The comparison of the obtained μ-Fe cross section with available μ-, e- and σ-proton data as well as μ-, e- and σ-nucleus data indicates that;

• 1 At v ˜ 100 GeV, the virtual photon cross section on iron nucleus is almost the same as the real photon one, at least Q² ≳ 0.1 GeV²/c², and is about 70% of the cross section on proton times the atomic mass number of iron, i.e. the shadowing effect is clearly seen.
• 2 Up to TeV region, this virtual photon cross section on iron does not increase significantly. contrary to the tendency of the real photon cross section on proton around 100 GeV. This suggests most likely that the shadowing still increases with energy at such high energies.