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1.
Sadao Arai Masanori Ishikura Kiyoshi Sato Takamichi Yamagishi 《Journal of heterocyclic chemistry》1995,32(3):1081-1083
The 16c-azonia[6]helicene salts, in which a carbon atom at the inner helix skeleton of [6]helicene is replaced by a quaternary nitrogen atom, have been synthesized by photo-induced intramolecular quater-nization of 2-[2-(1-chloronaphthyl)vinyl]benzo[h]quinolines in acetonitrile. 相似文献
2.
Hisanobu Ogoshi Kazurni Saita Ken-ichi Sakurai Takamichi Watanabe Hiroo Toi Yasuhiro Aoyama 《Tetrahedron letters》1986,27(52):6365-6368
Described is the preparation of chiral octaethylporphyrin derivatives having two 2-substituted naphthyl groups in a trans orientation at the 5- and 15-meso positions and formyl or hydroxymethyl or alkoxymethyl group derived therefrom at the 10-meso position. One of the derivatives has been successfully resolved into enantiomers by means of HPLC. 相似文献
3.
We have measured the nuclear susceptibility of 3He in Grafoil filled with pure liquid 3He over the pressure region between 0.6 and 31.38 bars and at temperatures down to 0.5 mK with a cw NMR method. The nuclear magnetization corresponding to the adsorbed 3He layers on the Grafoil surface shows a strong ferromagnetic tendency with a periodic behavior as a function of liquid pressure. This observation is attributable to the growth of third and fourth solid 3He layers with the liquid pressure increase. The pressure dependence of the Weiss temperature indicates the third layer is completed at 19 bars and the fourth probably at 28 bars. The number of localized spins estimated from the solid magnetization is almost doubled from 0 to 28 bars, being consistent with this scenario. 相似文献
4.
The Critical Effect of Niobium Doping on the Formation of Mesostructured TiO2: Single‐Crystalline Ordered Mesoporous Nb‐TiO2 and Plate‐like Nb‐TiO2 with Ordered Mesoscale Dimples 下载免费PDF全文
Takamichi Matsuno Dr. Yoshiyuki Kuroda Prof.Dr. Atsushi Shimojima Prof.Dr. Hiroaki Wada Prof.Dr. Kazuyuki Kuroda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):13073-13079
Highly ordered mesoporous niobium‐doped TiO2 with a single‐crystalline framework was prepared by using silica colloidal crystals with ca. 30 nm in diameter as templates. The preparation of colloidal crystals composed of uniform silica nanoparticles is a key to obtain highly ordered mesoporous Nb‐doped TiO2. The XPS measurements of Nb‐doped TiO2 showed the presence of Nb5+ and correspondingly Ti3+. With the increase in the amount of doped Nb, the crystalline phase of the product was converted from rutile into anatase, and the lattice spacings of both rutile and anatase phases increased. Surprisingly, the increase in the amount of Nb led to the formation of plate‐like TiO2 with dimpled surfaces on one side, which was directly replicated from the surfaces of the colloidal silica crystals. 相似文献
5.
Photoswitching of the transformation between seconds and hours time-scales is demonstrated using the threading of per-hydroxylated pillar[5]arene onto the azobenzene-end of a viologen derivative. When the azobenzene moiety was in the trans form, the threading of per-hydroxylated pillar[5]arene quickly took place at 25 °C and could not be monitored directly. The exchange rate (k) and half-life time (t(1/2)) examined by 2D EXSY NMR spectroscopy were found to be 0.209 ± 0.013 s(-1) and 3.33 ± 0.21 s, respectively. In contrast, the cis form of the azobenzene moiety required very long time (k = 2.14 ± 0.27 × 10(-5) s(-1), t(1/2) = 9.13 ± 1.2 h) to thread per-hydroxylated pillar[5]arene at 25 °C. Photoisomerization from the trans to the cis form generated the following increment of free energy of activation at 25 °C: ΔG(in)(?) (cis form) - ΔG(in)(?) (trans form) = 22.8 ± 0.24 kJ mol(-1), which led to the time-scale transformation. The tuning of the threading was also accomplished by heating/cooling: the rate constants increased on heating and decreased on cooling. 相似文献
6.
It was found that (2 + 2) cycloaddition reaction of diketene with Schiff bases was effectively promoted by imidazole as a catalyst to afford 3-acetyl-2-azetidinone derivatives 4. As an application of this new method, a practical asymmetric synthesis of 4 and its conversion into (3S,4S)-4-carboxy-1-(di-p-anisylmethyl)-3-[(R)-1-hydroxyethyl]-2- azetidinone, which is a key intermediate for the synthesis of carbapenem and penem antibiotics, were accomplished. 相似文献
7.
S. Sunagawa und M. Doi 《Colloid and polymer science》1978,256(3):302
Ohne Zusammenfassung 相似文献
8.
Yamamoto K Sunagawa Y Takahashi H Muramatsu A 《Chemical communications (Cambridge, England)》2005,(3):348-350
Single nanometer-sized metallic Ni particles have been successfully deposited inside a hexagonally ordered mesoporous silica material by using a liquid-phase reductive deposition method. 相似文献
9.
The normal dissolution rates, the slopes and the average velocities of dissolution steps of etch pits on the (111) face of a K-alum crystal, originating from dislocations with Burgers vector 110, were measured in relation to the surface undersaturations. From the mutual relations, it was shown that the dissolution was controlled by both diffusion and surface kinetic processes, although the contribution of the latter process was smaller than in the case of growth. It was also demonstrated that the normal dissolution rate was always larger than the growth rate. This is attributed to the fact that the slopes of growth hillocks are invariably smaller than those of etch pits. 相似文献
10.
Marienfeld S Sunagawa T Fabrikant II Braun M Ruf MW Hotop H 《The Journal of chemical physics》2006,124(15):154316
In a joint experimental and theoretical effort, we have studied dissociative electron attachment (DEA) to the CF3Br molecule at electron energies below 2 eV. Using two variants of the laser photoelectron attachment method with a thermal gas target (T(G) = 300 K), we measured the energy dependent yield for Br- formation over the range E = 3-1200 meV with resolutions of about 3 meV (E < 200 meV) and 35 meV. At the onsets for excitation of one and two quanta for the C-Br stretching mode nu3, downward cusps are detected. With reference to the recommended thermal (300 K) attachment rate coefficient k(A)(CF3Br) = 1.4 x 10(-8) cm3 s(-1), absolute cross sections have been determined for Br- formation. In addition, we studied Br- and (CF3Br)Br- formations with a seeded supersonic target beam (10% CF3Br in helium carrier gas, with a stagnation pressure of 1-4 bars and nozzle temperatures of 300 and 600 K) and found prominent structure in the anion yields due to cluster formation. Using the microwave pulse radiolysis swarm technique, allowing for controlled variation of the electron temperature by microwave heating, we studied the dependence of the absolute DEA rate coefficient on the mean electron energy E over the range of 0.04-2 eV at gas temperatures T(G) ranging from 173 to 600 K. For comparison with the experimental results, semiempirical resonance R-matrix calculations have been carried out. The input for the theory includes the known energetic and structural parameters of the neutral molecule and its anion; the parameters of the resonant anion curves are chosen with reference to the known thermal rate coefficient for the DEA process. For the gas temperature T(G) = 300 K, good overall agreement of the theoretical DEA cross section with the experimental results is observed; moreover, rate coefficients for Br- formation due to Rydberg electron transfer, calculated with both the experimental and the theoretical DEA cross sections, are found to agree with the previously reported absolute experimental values. At T(G) = 300 K, satisfactory agreement is also found between the calculated and experimental attachment rate coefficients for mean electron energies E = 0.04-2 eV. The strong increase of the measured rate coefficients with rising gas temperature, however, could be only partially recovered by the R-matrix results. The differences may result from the influence of thermal excitations of other vibrational modes not included in the theory. 相似文献