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1.
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. 相似文献
2.
M. K. Kubo Y. Sakai T. Tominaga K. Nishiyama K. Nagamine 《Journal of Radioanalytical and Nuclear Chemistry》1989,136(1):61-66
Diamagnetic muon yields /PD/ in various metal acetylacetonates were measured at room temperature by the muon spin rotation technique. We have found a clear difference in PD 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. 相似文献
3.
An analytical method has been developed for determination of dextromethorphan (DMP) and dextrorphan (DRP) in human hair by gas chromatography–mass spectrometry (GC–MS). Hair samples (30 mg) were washed with distilled water and acetone and cut into small fragments (<1 mm) before extraction with methanol. The extracts were evaporated to dryness and then derivatized by use of BSTFA containing 1% TMCS, for preparation of the trimethylsilyl (TMS) derivative of DRP. The extract (1 μL) was then injected into the GC–MS. Recoveries of DMP and DRP at 7.0 and 22.5 ng mg?1 were in the range 90.6–97.2% with intra-assay and inter-assay precision of less than 5.7% and 4.7%, respectively. LOD and LOQ were, respectively, 0.67 and 2.13 ng mg?1 for DMP and 0.14 and 0.47 ng mg?1 for DRP. The responses were linear with correlation coefficients (r > 0.9995) for the drugs studied. The applicability of the method was proven by analysis of authentic hair samples. 相似文献
4.
Kyo Shiina 《Journal of organometallic chemistry》1986,310(3):C57-C59
A new type of polymer, poly[o-(disilanylene)phenylene] was prepared via ring opening polymerization, at the Si---Si bond, of 1,1,2,2-tetramethyl-1,2-disilabenzocyclobutene. 相似文献
5.
6.
Yamamoto Y Ishii J Nishiyama H Itoh K 《Journal of the American Chemical Society》2004,126(12):3712-3713
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. 相似文献
7.
[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 AlCl3HCl 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. 相似文献
8.
C. G. Overberger T. Nishiyama 《Journal of polymer science. Part A, Polymer chemistry》1981,19(2):311-330
(+) (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. 相似文献
9.
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. 相似文献
10.
Crucial role of three-center hydrogen bonding in a challenging chiral molecular recognition 总被引:1,自引:0,他引:1
Kim SG Kim KH Kim YK Shin SK Ahn KH 《Journal of the American Chemical Society》2003,125(45):13819-13824
The enantio-discrimination of beta-chiral primary ammonium ions is achieved by a rational approach that utilizes three-center (bifurcated) hydrogen bonding. The extraction experiments on various selected guests reveal that the bifurcated H-bonding plays a crucial role for the chiral discrimination. The X-ray data obtained for an inclusion complex substantiate such interactions. Using the bifurcated H-bonding, the chiral molecular recognition with our C(3)-symmetric tripodal oxazoline receptors is extended generally toward ammonium ions of alpha-, beta-, and alpha,beta-chiral amines. Simple molecular models, evoking the bifurcated H-bonding, explain the chiral discrimination modes. 相似文献