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1.
Mechanism of gold adsorption by persimmon tannin gel. 总被引:1,自引:0,他引:1
Gold adsorption by persimmon tannin (PT) gel from a solution containing hydrogen tetrachloroaurate(III) was examined. A flow-rate examination in a column system indicated the reduction of Au(III) ion to Au(0). XRD patterns clarified the existence of Au(0) on the gel which adsorbed gold. The gel could also adsorb colloidal Au(0) prepared independently. A model consisting of ligand exchange, Au(III) reduction to Au(0), and resulting Au(0) adsorption by PT gel was presented for the gold adsorption mechanism. 相似文献
2.
Kouichi Ohe Tomomi Yokoi Koji Miki Fumiaki Nishino Sakae Uemura 《Journal of the American Chemical Society》2002,124(4):526-527
The reaction of cis vicinal acetylethynylcyclopropanes 1 with a catalytic amount of M(CO)5(THF) (M = Cr or W) in the presence of Et3N at room temperature gave ortho-substituted phenols 7 in good yields as valence isomerized products. In the absence of Et3N the reactions did not work at all. The reaction of a cyclopropane having an ester or an amide instead of an acetyl moiety with M(CO)5(THF) did not take place, whereas an ethynylvinylcyclopropane gave a mixture of 1- and 2-substituted 1,3,5-cycloheptatrienes. These valence isomerization reactions are assumed to proceed via the formation of vinylidene-metal intermediates 2 from terminal alkynyl moieties followed by [3,3]sigmatropy of 2 to give seven-membered carbene complexes 3. 相似文献
3.
Dr. Yohei Hattori Tatsuya Maejima Yumi Sawae Jun-ichiro Kitai Prof. Masakazu Morimoto Dr. Ryojun Toyoda Prof. Hiroshi Nishihara Prof. Satoshi Yokojima Dr. Shinichiro Nakamura Prof. Kingo Uchida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11441-11450
The cyclization reaction of diarylethenes having an azulene ring occurs only via higher excited states. Novel diarylethenes having an azulene ring with a strong donor or acceptor were synthesized and examined in these reactions. A derivative having an electron-donating 1,3-benzodithiol-2-ylidenemethyl group at the 1-position of the azulene ring showed photochromism, whereas neither a derivative having a π-conjugated electron-donating group at the 3-position of the azulene ring nor derivatives having a π-conjugated electron-withdrawing group at the 1- or 3-position of the azulene ring showed any photochromism. The photoreactivities of these compounds were explained by calculating forces and bond orders on the excited states using density functional theory (DFT) and time-dependent (TD)-DFT. 相似文献
4.
Hiroya Takada Yoshiaki Nishibayashi Sanjay Kumar Srivastava Kouichi Ohe Sakae Uemura 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):629-632
Asymmetric intramolecular selenocyclisation of alkenoic acids, alkenols and alkenyl urethanes using chiral ferrocenylselenenyl cations proceeds smoothly to give the corresponding lactones, cyclic ethers and N-heterocyclic compounds, respectively, in moderate yields with very high diastereoselectivities. 相似文献
5.
Hiroya Takada Yoshiaki Nishibayashi Kouichi Ohe Sakae Uemura 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):363-364
Prochiral sulfides reacted with Phl=NTs in the presence of a catalytic amount of Cu(I) salt together with a chiral 4,4′-disubstituted bis(oxazoline) ligand to afford the corresponding chiral sulfimides. 相似文献
6.
Nobuyuki Ichinose Masahide Hagiri Jun-ichiro Kinugasa Nobuyuki Shichi Toshihiro Nakayama 《Research on Chemical Intermediates》2013,39(1):425-435
A charge-transfer (CT) complex of NOBF4 and hexamethoxybenzene (HMB), which gives out HMB?+ as a “fluorescent radical cation probe,” upon one-electron oxidation, has been designed to explore the excited state dynamics of contact radical ion pairs by laser-induced fluorescence and femtosecond transient absorption spectroscopic techniques. The acetonitrile solution of the CT complex showed weak fluorescence with a similar spectrum to that observed for free excited HMB radical cation (HMB?+*), suggesting the formation of HMB?+* upon the one-photonic excitation of the CT complex. The laser-power dependence of the fluorescence intensity supported the one-photonic excitation event. We have also observed a short-lived transient species but no long-lived species by femtosecond laser flash photolysis of the CT complex. The lifetime (6.5 ps) was in good accordance with its fluorescence quantum yield (2.5 × 10?5) and was able to assign the transient species to the fluorescent state, an excited radical ion pair [HMB ?+*/NO?]. All the events were completed within the inner sphere and the short lifetime of the transient species could be attributed to rapid back-electron transfer. It is concluded that the excited radical cation character in the excited state of the CT complex originates from the radical ion character in the CT complex in the ground state and that a relatively long lifetime of HMB?+* facilitates its observation even in the contact ion pair. 相似文献
7.
We consider magnetotransport properties in a conducting chiral helimagnet, where the magnetic kink crystal (MKC) is formed under weak magnetic field applied perpendicular to the helical axis. The MKC behaves as a magnetic superlattice potential and results in Bragg scattering of conduction electrons. Tuning of the weak magnetic field enables us to control the size of the superlattice Brillouin zone and gives rise to a series of divergent resistivity anomalies originating from resonant Bragg scatterings. We discuss as well a nontrivial magnetic structure in the resonant states realized in the subsystem of the itinerant electrons. 相似文献
8.
We discuss the identification problem for current dipoles in a spherically symmetric conductor. This mathematical model is used for a biomedical inverse problem such as the source current identification for the human brain activity. We have already proposed a direct identification method for this inverse source problem using observations of the magnetic fields outside of the conductor. One of the difficulties of current dipole identification using the magnetic fields is caused by the fact that magnetic field does not include any information about the radial component of dipole moments. In this paper, we consider an improvement of the direct method to identify both radial and tangential components of current dipole moments by combining electric and magnetic observation data. Furthermore, our approach is effective in the case where the number of dipoles is unknown. 相似文献
9.
10.
New structurally constrained BODIPY dyes having electron-donating substituents were synthesized. As the key compounds for the construction of the BODIPY dyes, 1′H-spiro-[fluorene-9,4′-indeno[1,2-b]pyrrole] (sp-FIP) derivatives with electron-donating groups, such as OMe and NMe2 at its 6′-position, were prepared using palladium-catalyzed intramolecular direct C-H arylation of a pyrrole moiety. The resulting BODIPY dyes showed bathochromic shift in absorption and fluorescence spectra in comparison to the unsubstituted analogs. Furthermore, pH-dependent reversible spectrum changes of the BODIPY dye were observed with the addition of trifluoroacetic acid (TFA) and subsequent addition of i-Pr2NEt. 相似文献