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排序方式: 共有254条查询结果,搜索用时 31 毫秒
71.
Akiko Sekine Hidehiro Uekusa Yuji Ohashi Kimihiro Yoshimura Mikio Yagi Jiro Higuchi 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(12):1462-1464
The crystal structures of 4-nitro-9,10-dihydrophenanthrene, C14H11NO2, (I), and 4-nitrophenanthrene, C14H9NO2, (II), the latter having two crystallographically independent molecules, show that the molecules are not planar. The dihedral angles between the phenyl rings of the biphenyl skeletons are 28.64 (8)° for (I), and 10.34 (15) and 11.75 (13)° for the two molecules of (II). The differences in the dihedral angles have an effect on the photochemical reactivity of the molecules. 相似文献
72.
Prof. Dr. Takanori Iwasaki Shin Murakami Prof. Dr. Youhei Takeda Prof. Dr. Gaku Fukuhara Prof. Dr. Norimitsu Tohnai Prof. Dr. Yumi Yakiyama Prof. Dr. Hidehiro Sakurai Prof. Dr. Nobuaki Kambe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(65):14817-14825
The relationship between the photophysical properties and molecular orientation of 1,3,6,8-tetraalkylpyrenes in the solid state is described herein. The introduction of alkyl groups with different chain structures (in terms of length and branching) did not affect the photophysical properties in solution, but significantly shifted the emission wavelengths and fluorescence quantum yields in the solid state for some samples. Pyrenes bearing ethyl, isobutyl, or neopentyl groups at the 1-, 3-, 6-, and 8-positions showed similar emission profiles in both the solution and solid states. In contrast, pyrenes bearing other alkyl groups exhibited an excimer emission in the solid state, similar to that of the parent pyrene. On studying the photophysical properties in the solid state with respect to the obtained crystal structures, the observed solid-state photophysical properties were found to depend on the relative position of the pyrene chromophores. The solid-state photophysical properties can be controlled by the alkyl groups, which provide changing crystal packing. Among the pyrenes tested, 1,3,6,8-tetraethylpyrene showed the highest fluorescence quantum yield of 0.88 in the solid state. 相似文献
73.
Periodic Oscillatory Motion of a Self-Propelled Motor Driven by Decomposition of H2O2 by Catalase
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Prof. Satoshi Nakata Mio Nomura Hiroya Yamamoto Prof. Shunsuke Izumi Prof. Nobuhiko J. Suematsu Prof. Yumihiko Ikura Prof. Takashi Amemiya 《Angewandte Chemie (International ed. in English)》2017,56(3):861-864
A self-propelled motor driven by the enzymatic reaction of catalase adsorbed onto a filter paper floating on an aqueous solution of H2O2 was used to study nonlinear behavior in the motor's motion. An increase in the concentration of H2O2 resulted in a change from no motion to irregular oscillatory motion, periodic oscillatory motion, and continuous motion. The mechanisms underlying oscillation and mode bifurcation are discussed based on experimental results on O2 bubble formation and growth on the underside of the motor. 相似文献
74.
Sequential SNAr Reaction/Suzuki–Miyaura Coupling/C−H Direct Arylations Approach for the Rapid Synthesis of Tetraaryl‐Substituted Pyrazoles
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Taiki Morita Daisuke Kobayashi Keisuke Matsumura Dr. Kohei Johmoto Dr. Hidehiro Uekusa Dr. Shinichiro Fuse Prof. Dr. Takashi Takahashi 《化学:亚洲杂志》2015,10(8):1626-1630
A rapid synthesis of 1,3,4,5‐tetraaryl‐substituted pyrazoles has been achieved through a sequence of SNAr reaction/Suzuki–Miyaura coupling/Pd‐catalyzed direct arylations that used 3‐iodo‐1H‐pyrazole as a scaffold. Pyrazoles with four different aryl groups were synthesized in a straightforward manner with no extra synthetic steps, such as protection/deprotection or the introduction of activating/directing groups, using readily available substrates and reagents. The developed synthetic approach enabled the structurally diverse synthesis of multiaryl‐substituted pyrazoles without using a glovebox technique. 相似文献
75.
Tomohiro Seki Taichi Ozaki Takuma Okura Kiyotaka Asakura Aya Sakon Hidehiro Uekusa Hajime Ito 《Chemical science》2015,6(4):2187-false
In this study, we report the interconvertible tetracolored solid state photoluminescence of gold(i) isocyanide complex 2 upon various external stimuli through solid state structural changes. Soaking complex 2 in acetone yields blue emission as a result of the formation of 2B. The subsequent removal of acetone yields 2G through a crystal-to-crystal phase transition, which exhibits green emission. This green-emitting solid 2G exhibits stepwise emission color changes to yellow and then to orange upon mechanical stimulation by ball-milling, which corresponds to the formation of 2Y and 2O, respectively. 2B could be recovered upon the addition of acetone to 2G, 2Y, and 2O. Thus, these four emitting solid states of 2 can be switched between repeatedly by means of acetone soaking and the application of mechanical stimulation. Importantly, single crystal and powder X-ray diffraction (PXRD) studies fully show the detailed molecular arrangements of 2B, 2G, and 2Y. This is the first mechanochromic compound to show interconvertible four color emission in the solid state. We also present the first example of using PXRD measurements and the Rietveld refinement technique for the structural analysis of a ground powder in a luminescence mechanochromism study. We obtained complete molecular-level structural information of the crystalline states of 2B, 2G, 2Y, and 2O. In comparison with a more solvophobic analogue 1, we suggest that the weak interaction of 2 with acetone in the solid state would allow a solvent inclusion/release mode, which is an important structural factor for the unprecedented multicolor mechanochromic luminescence. 相似文献
76.
Hidehiro Suzuki Noritaka Usami Akiko Nomura Toetsu Shishido Kazuo Nakajima Takashi Suemasu 《Journal of Crystal Growth》2010,312(22):3257-3260
We investigated the impact of an amorphous Ge (a-Ge) thin layer inserted at the amorphous Si (a-Si)/Al interface on Al-induced crystallization. In situ observation of the growth process clarified that the nucleation rate is drastically reduced by insertion of a-Ge, which led to increase in the average size of crystal grains. This was interpreted as resulting from decrease in the driving force of crystallization, mainly due to the larger solubility of Ge in Al than that of Si in Al. The obtained films were SiGe alloys with lateral distribution of Ge content, and its origin is discussed based on the two-step nucleation process. 相似文献
77.
In order to prepare SiO(2) nanoparticles that are dispersible in various organic solvents, an anionic surfactant 1, which branches into a hydrophobic chain and a hydrophilic chain, was adsorbed on to SiO(2) nanoparticles through a layer-by-layer surface modification route using polyethyleneimine (PEI). First, the relationship among the additive content of PEI, adsorbed content of PEI, and the redispersion stability of the SiO(2) nanoparticles in water was investigated. While almost the entire PEI was adsorbed when the additive PEI content was lower than 67 mg/g of SiO(2), the adsorbed content of PEI became saturated when the additive content was increased above 90 mg/g of SiO(2). SiO(2) nanoparticles that were saturated with PEI could be redispersed into water at sizes close to their primary particle size without the large-scale formation of aggregates. Next, the anionic surfactant 1 was adsorbed on the SiO(2) nanoparticles by using a SiO(2) aqueous suspension saturated with adsorbed PEI. It was found that the adsorbed content of 1 increased almost linearly as the additive content was increased when the additive condition was below 1400 mg/g of SiO(2). Furthermore, SiO(2) nanoparticles adsorbed with 80 mg/g of SiO(2) of PEI and 810 mg/g of SiO(2) of 1 could be dispersed into various organic solvents with different polarities. This layer-by-layer modification technique can also be applied to Ag nanoparticles in order to prepare Ag nanoparticles that can be dispersed in various organic solvents. 相似文献
78.
79.
Mizuno H Sakurai H Amaya T Hirao T 《Chemical communications (Cambridge, England)》2006,(48):5042-5044
Oxidative ligand coupling of organoborates was catalyzed by VO(OEt)Cl(2) under oxygen atmosphere, which provides a versatile method for the selective synthesis of symmetrical or unsymmetrical biaryls. 相似文献
80.
Isocyanide-bound model hemes always adopt the (dxz, dyz)4(dxy)1 ground state, however, we have found that the replacement of porphyrin by diazaporphyrin leads to the formation of an unprecedented low-spin bis(tert-butylisocyanide) complex with the (dxy)2(dxz, dyz)3 ground state. 相似文献