Correlation between proton transfer and 35Cl NQR frequency as well as molecular geometry of chloranilic acid in co‐crystals with some organic bases

Proton transfer in hydrogen‐bonded organic co‐crystals of chloranilic acid with some organic bases was investigated by nuclear quadrupole resonance (NQR) spectroscopy. The ³⁵Cl NQR frequencies of chloranilic acid molecule as well as ¹⁴N NQR frequencies of the organic base molecule were measured with the conventional pulse methods as well as double‐resonance methods, respectively. The extent of proton transfer in the O···H···N hydrogen bond was estimated from Townes–Dailey analysis of the ¹⁴N NQR parameters. The ³⁵Cl NQR frequency and molecular geometry of chloranilic acid are correlated to the extent of proton transfer in the protonation process of the organic base molecule. It is shown that the hydrogen bond affects the π‐electron system of chloranilic acid. Geometry dependence of the O···H···N hydrogen bond, i.e. the H? N valence bond order versus the hydrogen‐bond geometry correlation is also discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

The First Observation of the Temperature-Dependent Phenomenon of Muon Catalyzed Fusion in Solid D–T Mixtures

A systematic study on muon catalyzed fusion (μCF) was conducted in solid deuterium and tritium (D–T) mixture. A variety of experimental conditions were investigated, i.e., tritium concentrations from 20 to 70%, temperatures from 5 to 16 K. A preliminary analysis result suggests a steep decrease in the dtμ-molecule formation rate with decreasing temperature, and also an increase in the probability for a muon reactivation after an α-sticking phenomenon. This revised version was published online in August 2006 with corrections to the Cover Date.     

Single-component organic semiconductors based on novel radicals that exhibit electrochemical amphotericity: preparation, crystal structures, and solid-state properties of N,N'-dicyanopyrazinonaphthoquinodiiminides substituted with an N-alkylpyridinium unit.

N,N'-Dicyanonaphthoquinodiimines fused with a pyrazine ring 1 were prepared from the corresponding quinones 4. The new acceptors 1 have a planar pi-system and undergo reversible two-stage 1e-reduction. Quaternization of the pyridyl substituent in 1d-f gave pyridinium derivatives 2d+, 2e+, and R-3+, respectively, which are stronger acceptors that undergo three-stage 1e-reduction. Upon electrochemical reduction of these cations, novel radicals 2d., 2e., and R-3. were generated and isolated as stable solids. The molecular geometries determined by X-ray analysis indicated that these radicals adopt a zwitterionic structure, in which the unpaired electron is located on the quinodiimine unit but not on the pyridyl group. These novel radicals undergo facile and reversible 1e-oxidation as well as two-stage 1e-reduction. The observed amphotericity endows the radicals with electrical conductivities (10(-5) to 10(-9) S cm-1), and these thus represent a new motif for single-component organic semiconductors.     

Mechanistic study on dimerization of acetylene with a Nieuwland catalyst

A mechanistic study on the Nieuwland catalysis for dimerization of acetylene is performed by detecting copper–acetylene and copper–monovinylacetylene π‐complexes and also by examining the kinetics under virtually the same reaction conditions employed in the industrial process. An efficient H/D exchange occurs between acetylene and protons in the Nieuwland catalytic system. Addition of a coordinating ligand to the conventional Nieuwland catalytic system results in improvement of the catalytic activity and selectivity for the acetylene dimerization. The kinetic analysis including the kinetic deuterium isotope effect provides valuable insight into the Nieuwland catalytic mechanism of the dimerization of acetylene. Copyright © 2008 John Wiley & Sons, Ltd.     

Precise measurement of hfs constant of the muonium substituted radical in cis-polyacetylene

The state of the muon in cis-polyacetylene was studied by muon spin rotation method under high transverse magnetic field. The most of the muons are found to be in muonium substituted radical state. The hyperfine coupling constant was determined to be 91 MHz with a line width of 10 MHz.     

Uptake of transition metal ions using liposomes containing dicetylphosphate as a ligand.

The uptake of Cu2+ was investigated using various types of liposomes composed of phosphatidylcholine (PC), cholesterol (Chol) and dicethylphosphate (DCP). DCP played a role as a ligand for Cu2+. Multilamellar vesicles (MLVs) were more effective for the uptake of Cu2+ compared to unilamellar vesicles prepared by the extrusion technique. The uptake efficiency of MLVs for Cu2+ was dependent on the molar ratio of DCP in MLVs. The uptake percent of Cu2+ was 92% using MLVs having a PC:DCP:Chol molar ratio of 4:3:3; 95% of the total vesicle Cu2+ was bound to DCP of the outer membrane surface of the MLVs, and the remaining 5% of the total Cu2+ was distributed into the interior side of the MLVs. MLVs having a PC:DCP:Chol molar ratio of 4:3:3 were also effective as separation media for Mn2+, Co2+, Ni2+ and Zn2+. The uptake efficiency of the MLVs for the transition-metal ions increased in the order Co2+ < Zn2+ < Ni2+ < Mn2+ < Cu2+.     

Synchrotron X-ray diffraction and absorption studies of CeM2X2 (M=Cu, Ni and X=Si, Ge) at high pressure

The equations of state of CeCu₂Si₂ and CeCu₂Ge₂ to about 60 GPa, as well as that of CeNi₂Ge₂ to 22 GPa and the valence state of Ce in CeCu₂Ge₂ to 20 GPa have been studied at room temperature in a diamond-anvil cell using synchrotron radiation sources. In each compound, the ambient-pressure phase (tetragonal ThCr₂Si₂-type structure) persisted to the highest pressure studied. The unit cell volumes of CeNi₂Ge₂ at ∼5 GPa and CeCu₂Ge₂ at ∼7 GPa, respectively, approached that of CeCu₂Si₂ taken at ambient pressure. From the equation-of-state data, the bulk modulus was derived to be 112.0±5.1 GPa for CeCu₂Si₂, 125.6±4.3 GPa for CeCu₂Ge₂, and 178.4±14.3 GPa for CeNi₂Ge₂. The valence state of Ce in CeCu₂Ge₂ remained trivalent throughout the pressure range investigated.