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981.
Dr. Yasushi Sato Prof. Dr. Hideki Kato Dr. Makoto Kobayashi Prof. Dr. Takaki Masaki Prof. Dr. Dae‐Ho Yoon Prof. Dr. Masato Kakihana 《Angewandte Chemie (International ed. in English)》2014,53(30):7756-7759
We report a new dicalcium silicate phosphor, Ca2?xEuxSiO4, which emits red light in response to blue‐light excitation. When excited at 450 nm, deep‐red emission at 650 nm was clearly observed in Ca1.2Eu0.8SiO4, the external and internal quantum efficiencies of which were 44 % and 50 %, respectively. The red emission from Ca2?xEuxSiO4 was strongly related to the peculiar coordination environments of Eu2+ in two types of Ca sites. The red‐emitting Ca2SiO4:Eu2+ phosphors are promising materials for next‐generation, white‐light‐emitting diode applications. 相似文献
982.
Shinji Tanimori Ushio Inaba Yoshihiro Kato Haruna Ura Hiroaki Kashiwagi Takeshi Nishimura Mitsunori Kirihata 《Research on Chemical Intermediates》2014,40(6):2157-2164
This paper reports our recent results from synthesis of some useful heterocycles, for example oxazolidinones, indoles, and quinoxalinones, by transition metal-catalyzed cascade processes. The scope and limitations of these procedures and the reaction mechanism for formation of the heterocycles are also discussed. 相似文献
983.
Kunihiro Kuwajima Maho Yagi-Utsumi Saeko Yanaka Koichi Kato 《Molecules (Basel, Switzerland)》2022,27(12)
Hydrogen/deuterium (H/D) exchange combined with two-dimensional (2D) NMR spectroscopy has been widely used for studying the structure, stability, and dynamics of proteins. When we apply the H/D-exchange method to investigate non-native states of proteins such as equilibrium and kinetic folding intermediates, H/D-exchange quenching techniques are indispensable, because the exchange reaction is usually too fast to follow by 2D NMR. In this article, we will describe the dimethylsulfoxide (DMSO)-quenched H/D-exchange method and its applications in protein science. In this method, the H/D-exchange buffer is replaced by an aprotic DMSO solution, which quenches the exchange reaction. We have improved the DMSO-quenched method by using spin desalting columns, which are used for medium exchange from the H/D-exchange buffer to the DMSO solution. This improvement has allowed us to monitor the H/D exchange of proteins at a high concentration of salts or denaturants. We describe methodological details of the improved DMSO-quenched method and present a case study using the improved method on the H/D-exchange behavior of unfolded human ubiquitin in 6 M guanidinium chloride. 相似文献
984.
Miki Kato Dr. Yasuhiro Ueta Prof. Dr. Shigekazu Ito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(7):2469-2475
The phosphanoxy-substituted phosphaalkene bearing the P=C−O−P skeleton can be prepared from diphosphene Mes*P=PMes* (Mes*=2,4,6-tBu3C6H2), and their use for catalysis is of interest. In this paper, complexation of the phosphanoxy-substituted phosphaalkenes with gold are investigated, and the catalytic activity of the mono- and bis(chlorogold) complexes are subsequently evaluated. Reaction of the P=C−O−P compound with (tht)AuCl (tht=tetrahydrothiophene) showed dominant coordination on the sp3 phosphorus, and complete coordination on the sp2 phosphorus required removal of tetrahydrothiophene. Atoms In Molecules (AIM) analysis based on the X-ray structure of the mono(chlorogold) complex indicated a pseudo coordinating interaction between the gold center and the P=C unit. The bis(chlorogold) complexes displayed conformational isomerism, and catalyzed the cycloisomerization/alkoxycyclization of 1,6-enyne and for hydration of terminal alkyne without activation treatment. Even the mono(chlorogold) complexes catalyzed the alkoxycyclization reactions without a silver co-catalyst, indicating that the alcohols were effective in activating the AuCl unit. 相似文献
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Enalapril (1.5–60 μ gl?1) in aqueous solution is extracted into dichloromethane as its ion-pair with bromothymol blue in an unsegmented flow system and quantified spectrophotometrically. Up to 80 samples h?1 can be processed, with r.s.d. of 1.0–3.4%. The degradation products of enalapril and excipients in the pharmaceutical dosage form do not interfere. 相似文献
990.
Reaction of an antihypotensive drug, etilefrin [alpha-[(ethylamino)methyl]-m-hydroxybenzyl alcohol], with nitrite under mildly acidic conditions produced N-nitrosoetilefrin [alpha-[(N-nitrosoethylamino)methyl]-m-hydroxybenzyl alcohol] (a mixture of syn and anti forms) (Iab) and diazo-N-nitrosoetilefrin [1-(4-diazo-3-oxo-1,5-cyclohexadienyl-2-(N-nitrosoethylamino )ethanol] (a mixture of syn and anti forms) (IIab). Treatment of etilefrin with an equivalent amount of nitrite at pH 3 and 37 degrees C for 4 h gave Iab (yield, 30%) and IIab (yield, 5%). Treatment of etilefrin with 4 eq of nitrite under the same conditions gave Iab (23%) and IIab (53%). Compounds Iab and IIab were each composed of two isomers due to the configuration of the N-nitroso group. While compound Iab was not mutagenic, compound IIab showed mutagenicity to Salmonella typhimurium TA98 and TA100 strains without metabolic activation. Specific mutagenic activity of IIab was 300 his+ revertant colonies for both TA98 and TA100 strains with a dose of 0.1 mumol. Addition of a microsomal activation system little affected the activity. It is noteworthy that this orally administered drug can produce a direct-acting mutagen by reaction with nitrite, which is present in the digestive tract. 相似文献