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81.
Aromatic and aliphatic α-haloketones were effectively dehalogenated by binary systems of sodium hydrogen sulfide (soft base) and a metal chloride such as tin (II) chloride, iron (II) chloride or chromium (III) chloride (hard acid). 相似文献
82.
P. Chewchinda O. Odawara H. Wada 《Applied Physics A: Materials Science & Processing》2014,117(1):131-135
The effect of energy density on the yield of silicon nanoparticles was studied. Silicon nanoparticles were prepared by laser ablation in ethanol. The yield of nanoparticles was calculated and its results indicate that high energy density led to more nanoparticles production. Particle size was also affected by varying energy density. From TEM images, higher energy density resulted in smaller nanoparticles, which can be explained by nucleation and growth theory. Photoluminescence spectra revealed blue shift of emission peak at high energy density supporting TEM results. Silicon peak was detected by EDS analysis along with oxygen. This means oxidation of silicon might occur within the sample. 相似文献
83.
Improved Synthesis and Reaction of 11‐Chloroneocryptolepines,Strategic Scaffold for Antimalaria Agent,and Their 6‐Methyl Congener from Indole‐3‐carboxylate
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Li Wang Wen‐Jie Lu Tomohito Odawara Ryuhei Misumi Zhen‐Wu Mei Wei Peng Ibrahim El‐Tantawy El‐Sayed Tsutomu Inokuchi 《Journal of heterocyclic chemistry》2014,51(4):1106-1114
Various 11‐chloro‐5‐methyl‐5H‐indolo[2,3‐b]quinolines (neocryptolepines) with different substituents on the quinoline ring, key intermediates for antimalaria agents, are prepared from the substituted N‐methylanilines, easily accessible by the N‐methylation of anilines, and indole‐3‐carboxylate as a counterpart. This protocol is benign in terms of the reduced number of steps to reach the target, compared with the known method using anilines, and easy product purification. Alternatively, their 6‐methyl congener is prepared by N‐methylation of the indole moiety of 2‐arylaminoindole‐3‐carboxylate followed by successive cyclization and chlorination. 11‐Chloroneocryptolepines are found more reactive than their 6‐methyl congener in the nucleophilic substitution at the C11 position. 相似文献
84.
Shingo Sato Toshikatsu Nojiri Nao Okuyama Koya Maeda Aoi Kirigane 《Journal of heterocyclic chemistry》2020,57(9):3342-3349
Condensation of 2 eq. of C-β-D-glucosylphloroacetophenone with glyoxylic acid in an aqueous solution of Na2CO3, followed by air oxidation in MeOH in the presence of 11 eq. of pyridine to afford a 36% yield of a bright red dye, xanthene bis-C-glycoside. This dye is 10 times more fluorescent (Φf [EtOH]581 nm = 3.9 × 10−2) and 7.5 times more water-soluble (57 mg/mL H2O) than the natural red pigment, carthamin. Detailed NMR analysis of its methyl analogs was used to confirm the structure of the dye as methyl 4,5-diacetyl-1,3,8-trihydroxy-3-oxo-3H-2,7-di-C-β-D-glucopyranosylxanthene-9-carboxylate from among three possible ring-closure isomers. Xanthene is safe and shows high light-resistance; therefore, xanthene bis-C-glycoside could be used as a food colorant or an in vivo probe. 相似文献
85.
Dynamic changes of melatonin in microdialysates from the pineal gland of a freely moving rat were repeatedly determined by using on-line high-performance liquid chromatography with electrochemical detection. The detection limit for melatonin, ca. 5 pg, was well below that achieved with other systems. We observed a drastic increase of extracellular pineal melatonin during the transitional phase from the light period to the dark period. This application of microdialysis is a useful tool in the study of the physiological role of the mammalian pineal body. 相似文献
86.
Vapor-phase fluorescence spectra from the second excited singlet state of pyrene and its derivatives
Vapor-phase fluorescence spectra have been measured for pyrene and its simple derivatives, i.e., pyrene-d10, 1-methylpyrene, and 4-methylpyrene. Each of these derivatives shows a weak fluorescence emission which is similar to the fluorescence from the second excited singlet state (S2) of pyrene and is to be assigned to the S2-fluorescence. The methyl substitution causes frequency shifts (Δν) in both absorption and fluorescence, and the Δν values for absorption and fluorescence transitions that are associated with the same excited state, i.e., the first excited singlet state (S1) or the second excited singlet state (S2), are approximately equal to each other. When the excitation energy increases, the S2-fluorescence shifts gradually to the red in almost the same way as the S1-fluorescence. The S2-fluorescence spectrum has a sort of mirror-image relation to the S2-absorption. A comparison of S2-emissions of pyrene and pyrene-d10 suggests that the ratio between the quantum yields of S2- and S1-fluorescence may be related to a ratio , where ?1 and ?2 are the densities of vibrational states in S1 and S2 at the energy of excitation. 相似文献
87.
Koya Aoi 《Zeitschrift für Physik A Hadrons and Nuclei》1971,246(1):71-83
We discuss the effects of the Pauli paramagnetism on the excess conductivity σfl due to fluctuations of the superconducting order parameter. We derived a formula for σfl for a thin film placed in a magnetic field of an arbitrary orientation α. It was found that σfl has a universal behavior as a function of some parameterp which depends on α and ΔH=H-H c. If ΔH is kept constant and σfl is measured as a function of α, in the absence of the Pauli paramagnetism σfl is maximum when the field is parallel to the film and is minimum when the field is perpendicular. But in high field superconductors due to the effect of the Pauli paramagnetism σfl becomes maximum at some intermediate field orientation. We also discussed the excess conductivity in magnetic alloys in which impurity spins are aligned by an external magnetic field. It was shown that in this case one should expect, with certain strengths of the external field, the excess conductivity which is non-monotonic in temperature. 相似文献
88.
Noriyoshi Matsumi Keita Kawaguchi Yousuke Hirota Keigo Aoi 《Journal of organometallic chemistry》2009,694(11):1776-1779
A series of novel fluoride anion responsive materials were facilely prepared by complex formation of poly(N-vinylcarbazole) with organoboron compounds in tetrahydrofuran. After addition of fluoride anion, visual color changes of fluorescence emission from green to blue were observed. The 11B NMR spectra shown that poly(N-vinylcarbazole)-borane complexes were converted to poly(N-vinylcarbazole) and fluoroborate in the presence of fluoride anion. Among the obtained poly(N-vinylcarbazole)-borane complexes prepared, poly(N-vinylcarbazole)-triethylborane complex exhibited the most distinct visual changes in fluorescence emissions. 相似文献
89.
The β-(trifluoromethyl)vinyl sulfides on treatment with n-BuLi/TMEDA at −78 °C were readily lithiated at an α-position of the sulfanyl group, and the generated β-trifluoromethyl-α-sulfanylvinyl anions were reacted with a variety of electrophiles to give the corresponding β-trifluoromethyl-α-functionalized-vinyl sulfides 4aa-4aq in good to excellent yields. The reactivity of some products has been examined. The palladium-catalyzed cross-coupling reaction as well as homo-coupling reaction of 4af provided the corresponding products in good yields, respectively. The Diels-Alder reaction of cyclic dienes and 14 derived from 4ao provided the desired six-membered cyclic products with high endo-trifluoromethyl group selectivity. 相似文献
90.
Analysis of magnetization transition in perpendicular magnetic recording for narrow transition width
Takeshi Kato Kenji MiuraHajime Aoi Hiroaki MuraokaYoshihisa Nakamura 《Journal of magnetism and magnetic materials》2008
In order to achieve high linear density recording, a narrow transition width or small transition parameter, a, is imperative. Reducing the grain size improves transition jitter and also reduces the transition width. The correlation between transition width and transition jitter was examined. The observed discrepancy from simple, analytical expressions introduces more realistic magnetization transitions with island magnetization reversals. It was found that island reversals increase the transition width, rather than the transition jitter, which must be suppressed to attain high linear density. 相似文献