Dynamics of muons in the ferroelectric material KDP

Muon spin relaxation in zero field and longitudinal field was measured in single crystal samples of KH₂PO₄ (KDP) and KD₂PO₄ (DKDP) over a temperature range of 5 K to 300 K. At low temperatures, diamagnetic muons and muon substituted radicals with nuclear hyperfine coupling can be observed. For both KDP and DKDP, a minor change was observed in the dynamics of the muon below 140 K. Above 140 K, the mobility of the muon appears to increase and the diffusion rate becomes faster with increasing temperature. Only a small increase in the relaxation rate is observed in KDP due to the presence of theH ⁺, suggesting that the relaxation effects probably originate from the³¹P.     

Diamagnetic muon yields of metal acetylacetonates

Diamagnetic muon yields /P_D/ in various metal acetylacetonates were measured at room temperature by the muon spin rotation technique. We have found a clear difference in P_D between complexes of typical elements and those of transition elements. We suggest that partially filled inner orbitals play some important role in determining the diamagnetic yield in these complexes.     

Synthesis of novel organoselenium as catalyst for Baeyer-Villiger oxidation with 30% H2O2

A novel diselenide was synthesized in good yield via only four steps from phenol, and was employed as the catalyst for the Baeyer-Villiger oxidation with 30% H₂O₂ to obtain lactones in good yields.     

Ru(II)-catalyzed chemo- and regioselective cyclotrimerization of three unsymmetrical alkynes through boron temporary tether. One-pot four-component coupling via cyclotrimerization/Suzuki-Miyaura coupling

The Ru(II)-catalyzed [2+2+2] cyclotrimerization of alkynylboronates, propargyl alcohol, and terminal alkynes proceeded chemo- and regioselectively to give rise to arylboronates, which were subjected to Suzuki-Miyaura cross-coupling with aryliodides to afford highly substituted biaryls in 53-76% yields.     

Medium-sized cyclophanes—XVII : Tetra-, hexa-, octa- and decahydropyrenes from [2.2]metacyclophane. Transannular dehydrogenation,isomerization, and disproportionation reactions by means of benzoyl peroxide,metal salts and sulfuric acids

[2.2]Metacyclophane (1) undergoes a variety of reactions according to the reagents and conditions. These include (1) substitution (path a), (2) transannular dehydrogenation (path b and c), (3) cycloisomerization (path d) and (4) transannular hydrogenation. A brief summary of these reactions is presented.The diversity of the reactions of 1 is further explored using benzoyl peroxide (BPO), cupric chloride, aluminum chloride, other metal salts, H₂SO₄ and FSO₃H. With BPO or cupric chloride, one-electron transfer mechanism is postulated. This involves a tautomeric ion pair formed by the intramolecular arylation with an aryl cation radical. A supporting evidence in favor of the mechanism is presented from experiments using various metal salts in different solvents.On the contrary, the reaction with aluminum chloride gives decahydropyrene (8) and octahydropyrene (11) together with cycloisomerization product 5 and dehydrogenation products 2, 3 and 4. When treated with AlCl₃HCl 1 gives similar products as above but the product ratios are quite different. The major product is 5 but only a trace amount of 8 is formed. The reaction with H₂SO₄ or FSO₃H also produce 2, 4, 5 and 11. Some mechanistic evidence in favor of the disproportionation reaction is presented.     

Vacancy ion-exclusion chromatography of carboxylic acids on a weakly acidic cation-exchange resin

In this preliminary study, a new approach to ion-exclusion chromatography is proposed to overcome the relatively poor conductivity detection response which occurs in ion-exclusion chromatography when acids are added to the eluent in order to improve peak shape. This approach, termed vacancy ion-exclusion chromatography, requires the sample to be used as eluent and a sample of water to be injected onto a weakly acidic cation-exchange column (TSKgel OApak-A). Vacancy peaks for each of the analytes appear at the retention times of these analytes. Highly sensitive conductivity detection is possible and sharp, well-shaped peaks are produced, leading to efficient separations. Retention times were found to be affected by the concentration of the analytes in the eluent, and also by the presence of an organic modifier such as methanol in the eluent. Detection limits for oxalic, formic, acetic, propionic, butyric and valeric acids were 0.1, 0.2, 0.3, 0.3, 0.4 and 0.5 microM, respectively, and linear ranges for some acids extended over two orders of magnitude. Precision values for retention times were 0.21% and for peak areas were <1.90%. The vacancy ion-exclusion chromatography method was found to give detection responses four to 10 times higher than conventional ion-exclusion chromatography using sulfuric acid eluent and two to five times higher than conventional ion-exclusion chromatography using benzoic acid eluent.     

Synthesis of asymmetric cyclopropyl acids and amines

(+) (S)- and (?) (R)-trans-1,2-cyclopropanedicarboxylic acids (C3A), (+) (S)- and (?) (R)-trans-1,2-diaminocyclopropanes (C3B), (+) (S)- and (?) (R)-trans-2-phenylcyclopropylamines (øC3B), (+) (S)- and (?) (R)-trans-1,2-bis(methylamino)-cyclopropanes (C3MB), and (+) (S)- and (?) (R)-trans-(2-phenylcyclopropyl)-methylamines (øC3MB) were prepared.     

Optimal laser control of ultrafast photodissociation of I2- in water: mixed quantum/classical molecular dynamics simulation

A linearized optimal control method in combination with mixed quantum/classical molecular dynamics simulation is used for numerically investigating the possibility of controlling photodissociation wave packets of I(2)(-) in water. Optimal pulses are designed using an ensemble of photodissociation samples, aiming at the creation of localized dissociation wave packets. Numerical results clearly show the effectiveness of the control although the control achievement is reduced with an increase in the internuclear distance associated with a target region. We introduce effective optimal pulses that are designed using a statistically averaged effective dissociation potential, and show that they semiquantitatively reproduce the control achievements calculated by using optimal pulses. The control mechanisms are interpreted from the time- and frequency-resolved spectra of the effective optimal pulses.