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111.
ON THE TWO FORMS OF INTERMEDIATE M OF BACTERIORHODOPSIN 总被引:1,自引:0,他引:1
Abstract— The decay time course of intermediate M of bacteriorhodopsin was investigated by flash spectrophotometry. The decay was composed of two exponentials showing the existence of two forms of intermediate absorbing around 410 nm. The two were very different in kinetic character whereas the absorption spectra were almost the same. The relative yield of the two components was a function of the intensity of the exciting flash and the slower component disappeared when the flash intensity was made very small. A model based on the trimeric cluster structure of bacteriorhodopsin is proposed. 相似文献
112.
Yamamoto T Umemura Y Sato O Einaga Y 《Journal of the American Chemical Society》2005,127(46):16065-16073
Thin films of cobalt-iron cyanide (Co-Fe Prussian blue) have been fabricated by means of the modified Langmuir-Blodgett (LB) method using a smectite clay mineral (montmorillonite). In this combined method, clay LB films play a template role in the formation of the Co-Fe Prussian blue thin layer. The films were revealed to possess a well-organized structure not only in perpendicular directions to the film surface but also in parallel directions to the film surface. The photoinduced electron transfer from the iron ion to the cobalt through the bridging cyanide in the films occurred at low temperature (8 K), similar to that in the bulk Co-Fe Prussian blue. The films clearly exhibited magnetic anisotropy with regards to the direction of the applied magnetic field. Moreover, the photoinduced magnetization effect in the films was also found to be anisotropic. 相似文献
113.
Yasuaki Maeda Kenji Okitsu Hiroyuki Inoue Rokuro Nishimura Yoshiteru Mizukoshi Hiroyuki Nakui 《Research on Chemical Intermediates》2004,30(7-8):775-783
Metal nanoparticles with a narrow size distribution could be prepared by sonolysis of aqueous solutions of metal cations in the presence of surfactants such as sodium dodecyl sulfate, polyethylene glycol monostearate, etc. The role of the surfactans is not only to stabilize formed particles, but also to produce reductive radicals in pyrolysis or hydrogen abstraction of OH radicals from surfactants. Particles with a smaller size could be obtained in a faster reduction rate with dilute metal cations concentration. Pt(IV) is consecutively reduced in two steps to Pt(0)via Pt(II). By comparing the sonolytical reduction withγ-ray radiolysis, two kinds of organic reducing radicals are proposed to contribute to the reduction. One (Rab) is an intermediate radical which is produced by hydrogen abstraction of OH radical from surfactant and effective only on the reduction of Pt(II) to Pt(0). The other (Rpy) is also an intermediate radical which is produced by thermal decomposition of surfactant at the interface between the cavity and bulk solution and effective on the reduction of Pt(IV) to Pt(II). 相似文献
114.
Kenji Okada Miharu Nakanishi Ken Ikigaki Yasuaki Tokudome Paolo Falcaro Christian J. Doonan Masahide Takahashi 《Chemical science》2020,11(30):8005
Controlling the direction of molecular-scale pores enables the accommodation of guest molecular-scale species with alignment in the desired direction, allowing for the development of high-performance mechanical, thermal, electronic, photonic and biomedical organic devices (host–guest approach). Regularly ordered 1D nanochannels of metal–organic frameworks (MOFs) have been demonstrated as superior hosts for aligning functional molecules and polymers. However, controlling the orientation of MOF films with 1D nanochannels at commercially relevant scales remains a significant challenge. Here, we report the fabrication of macroscopically oriented films of Cu-based pillar-layered MOFs having regularly ordered 1D nanochannels. The direction of 1D nanochannels is controllable by optimizing the crystal growth process; 1D nanochannels align either perpendicular or parallel to substrates, offering molecular-scale pore arrays for a macroscopic alignment of functional guest molecules in the desired direction. Due to the fundamental interest and widespread technological importance of controlling the alignment of functional molecules and polymers in a particular direction, orientation-controllable MOF films will open up the possibility of realising the potential of MOFs in advanced technologies.Orientation-controlled Cu2(Linker)2DABCO MOF films on macroscopic scales are fabricated for the development of high-performance devices; the direction of 1D nanochannels is controllable either perpendicular or parallel to substrates. 相似文献
115.
Two novel types of photomagnetic hybrid ultrathin film (film A and B) of metal cyanides have been fabricated by means of the
modified Langmuir–Blodgett method using a smectite clay mineral. Film A is composed of an amphiphilic azobenzene cation, a
montmorillonite, and Prussian Blue in which photocontrol in the magnetization was realized by the photoisomerization of azobenzene
chromophore. The observed photomagnetic efficiency was large (ca. 11%) due to the well-organized structure of the ultrathin
film. Film B is composed of a quaternary ammonium salt, a montmorillonite, and Co–Fe Prussian Blue in which the photoinduced
magnetization caused by the electron transfer exhibited an anisotropic response with regards to the direction of the applied
magnetic field. This phenomenon is ascribed to the unique structure of Co–Fe Prussian Blue formed onto the clay layer.
Contribution to special issue “Magnetic field effects in Electrochemistry” 相似文献
116.
Unno M Kawaguchi Y Kishimoto Y Matsumoto H 《Journal of the American Chemical Society》2005,127(7):2256-2263
The first synthesis of all four stereoisomers of 1,3,5,7-tetrahydroxy-1,3,5,7-tetraisopropylcyclotetrasiloxane, [i-PrSiO(OH)]4 (all-trans-, cis-cis-trans-, cis-trans-cis-, and all-cis-1), is presented. The starting compounds, all-trans-, cis-cis-trans-, cis-trans-cis-, and all-cis-1,3,5,7-tetraaryl-1,3,5,7-tetraisopropylcyclotetrasiloxanes, were prepared by the hydrolysis of the corresponding arylisopropyldichlorosilanes, i-PrArSiCl2 (Ar = Ph, p-tolyl), and subsequent separation of isomers. A combination of dephenylchlorination of tetraarylcyclotetrasiloxanes and the following hydrolysis proved to be an efficient method for the stereospecific transformation of aryl-substituted cyclotetrasiloxanes into (i-PrSiO(OH))4. For example, treatment of cis-trans-cis-1,3,5,7-tetraphenyl-1,3,5,7-tetraisopropylcyclotetrasilane with HCl and AlCl3, followed by hydrolysis in the presence of pyridine, resulted in the exclusive formation of cis-trans-cis-1 in 92% yield. The structures of cis-cis-trans-1, cis-trans-cis-1, and all-cis-1 were determined by X-ray crystallography. All isomers were found to construct unique packing structures by intermolecular hydrogen bonding; cis-trans-cis-1 composed an infinite antiladder structure, and cis-cis-trans-1 formed a sheetlike structure. 相似文献
117.
Takahiro Kumamaru Hiroshi Matsuo Yasuaki Okamoto Manabu Yamamoto Yuroku Yamamoto 《Analytica chimica acta》1986
Boron is converted to methyl borate, distilled and condensed, and selectively volatilized at 50°C into the plasma without interference from methanol, which quenches the plasma. The 3σ detection limit is 40 ng ml?1 boron, the calibration graph is linear up to 10 μg ml?1 and the r.s.d. 3.0% for 2.0 μg ml?1 (n = 10). Boron is determined in plant-tissue and steel standards. 相似文献
118.
Summary A new cationic dye, 1-(10-bromodecyl)-4-(4-aminonaphthylazo)-pyridinium bromide, was synthesized and evaluated as a new reagent for the determination of anionic surfactants. The reagent reacts with anionic surfactants, such as sodium dodecylsulphate and sodium dodecylbenzenesulphonate, to produce an ion associate in an aqueous medium. The colour change occurs simultaneously, and the colour development is very stable. This makes it possible to determine anionic surfactants directly by spectrophotometry without solvent extraction. The stoichiometric ratio of the ion associate was found to be 1:1 by the mole ratio method. The calibration graph was linear up to 2.5×10–6 mol/l. The apparent molar absorptivity of the ion associate was 5.3×104 l mol–1 cm–1 (at 595 nm). The relative standard deviation (n=10) for 1.2×10–6 mol/l sodium dodecylsulphate was 4.9%. The proposed method was applied to the determination of anionic surfactants in tap and river waters. 相似文献
119.
Prof. Dayu Wu Dr. Hua-Qing Yin Zeshi Wang Mingren Zhou Chengfeng Yu Jing Wu Huixian Miao Dr. Takashi Yamamoto Wenjiang Zhaxi Zetao Huang Luying Liu Prof. Wei Huang Dr. Wenhui Zhong Prof. Yasuaki Einaga Prof. Jun Jiang Prof. Zhi-Ming Zhang 《Angewandte Chemie (International ed. in English)》2023,62(18):e202301925
Spin manipulation of transition-metal catalysts has great potential in mimicking enzyme electronic structures to improve activity and/or selectivity. However, it remains a great challenge to manipulate room-temperature spin state of catalytic centers. Herein, we report a mechanical exfoliation strategy to in situ induce partial spin crossover from high-spin (s=5/2) to low-spin (s=1/2) of the ferric center. Due to spin transition of catalytic center, mixed-spin catalyst exhibits a high CO yield of 19.7 mmol g−1 with selectivity of 91.6 %, much superior to that of high-spin bulk counterpart (50 % selectivity). Density functional theory calculations reveal that low-spin 3d-orbital electronic configuration performs a key function in promoting CO2 adsorption and reducing activation barrier. Hence, the spin manipulation highlights a new insight into designing highly efficient biomimetic catalysts via optimizing spin state. 相似文献
120.
Bai YL Tao J Huang RB Zheng LS Zheng SL Oshida K Einaga Y 《Chemical communications (Cambridge, England)》2008,(15):1753-1755
A three-dimensional mixed-valence iron complex with NiAs-type topology, [(Fe(III)(3)O)Fe(II)(TA)(6)(H(2)O)(3)].(ClO(4))(2)(NO(3))(EtOH)(H(2)O)(2) (1, HTA = tetrazole-1H-acetic acid), shows spin-crossover behavior that was characterized via variable-temperature crystal structures, M?ssbauer spectra and magnetic susceptibilities, the pressure effects on the transition behavior were also studied. 相似文献