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991.
Katsunobu Yamamoto Tianshu Zhou Min Zhu Takeshi Kato Litong Jin 《Analytica chimica acta》2003,480(1):109-117
In this paper, preparation of a novel pH ultramicrosensor and its physiological application has been discussed. A tungsten nanoelectrode was produced by an etching method in 0.1 mol/l NaOH solution at the potential of +0.4 V (versus Ag/AgCl reference electrode) for about 100 s and the diameters ranged from 500 to 800 nm. The pH ultramicrosensor was fabricated by producing WO3 at W nanoelectrode surface by electrooxidation in 2.0 mol/l H2SO4 solution between 1.0 and 2.0 V. At last, Nafion was coated on the surface of WO3 to protect the pH ultramicrosensor. The W/WO3 pH ultramicrosensor exhibited a good pH linear region from 2.0 to 12.0 with a super-Nernstian slope of −53.5 ± 0.5 mV/pH unit. Response times ranged from 3 s at about pH 6.0-7.0 up to 15 s at high pH. An interference of various ions to the pH measurement was also studied in this paper. We also studied the lifetime, stability and reproducibility of the W/WO3 pH ultramicrosensor. In order to testing the performance of W/WO3 ultramicrosensor, we applied it to measure the extracellular pH values and a pH variation was also given about the normal, damaged and recovery endothelial cells. 相似文献
992.
Gevorgyan V Radhakrishnan U Takeda A Rubina M Rubin M Yamamoto Y 《The Journal of organic chemistry》2001,66(8):2835-2841
A new concept of highly chemo- and regioselective formation of the benzene ring by a palladium-catalyzed formal [2 + 2 + 2] sequential intermolecular trimerization of alkynes is proposed. Homodimerization of terminal alkynes and subsequent [4 + 2] benzannulation with diynes gives tetrasubstituted benzenes in moderate to good yields. The introduction of two different alkynes (terminal and internal) in the first step of the sequence allows for construction of pentasubstituted benzenes from three different acyclic acetylenic units. In all cases the tetra- and pentasubstituted benzenes are formed as a single reaction product without being accompanied by any of regio- or chemoisomers. A significant acceleration of the sequential trimerization reaction in the presence of Lewis acid/phosphine combined system was observed. Mechanistic studies reveal that the Lewis acid assisted isomerization of the E-enyne formed in the first step of the sequence to the more reactive Z-isomer is responsible for the observed acceleration effect. The proposed methodology provides a conceptually new and synthetically useful route to multifunctional aromatic compounds. 相似文献
993.
Jyunichi Koyanagi Katsumi Yamamoto Kouji Nakayama Akira Tanaka 《Journal of heterocyclic chemistry》1994,31(5):1303-1304
Phthalic anhydride in THF was added to 3-lithiofuran 2 in THF to give 3,3-di-(3-furyl)-1,3-dihy-droisobenzofuran-1-one 4 . On the other hand, 2 in THF was added to phthalic anhydride in THF to give 2-(3-furanoyl)benzoic acid 3 by the inverse addition method. Further, the parent naphtho[2,3-b]furan-4,9-dione 1 was obtained from the reaction of 3 with two equimolar amounts of LDA. 相似文献
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Prof. Dr. Kazuyuki Takahashi Kiko Kawamukai Mitsunobu Okai Prof. Dr. Tomoyuki Mochida Dr. Takahiro Sakurai Prof. Dr. Hitoshi Ohta Dr. Takashi Yamamoto Prof. Dr. Yasuaki Einaga Prof. Dr. Yoshihito Shiota Prof. Dr. Kazunari Yoshizawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(4):1253-1257
Unprecedented anionic FeIII spin crossover (SCO) complexes involving a weak‐field O,N,O‐tridentate ligand were discovered. The SCO transition was evidenced by the temperature variations in magnetic susceptibility, Mössbauer spectrum, and coordination structure. The DFT calculations suggested that larger coefficients on the azo group in the HOMO?1 of a ligand might contribute to the enhancement of a ligand‐field splitting energy. The present anionic SCO complex also exhibited the light‐ induced excited‐spin‐state trapping effect. 相似文献