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81.
Newly developed phosphino-bisphenol 1c was found to be an efficient organocatalyst for the aza-Morita-Baylis-Hillman reaction. High enantioselectivity up to 96% ee was obtained with catalyst loading of 1 mol %. 相似文献
82.
Dr. Mitsuaki Yamauchi Kanako Nakatsukasa Naoki Kubo Prof. Dr. Hiroko Yamada Prof. Dr. Sadahiro Masuo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(1):e202314329
Colloidal quantum dots (QDs) exhibit important photophysical properties, such as long-range energy diffusion, miniband formation, and collective photoluminescence, when aggregated into well-defined superstructures, such as three-dimensional (3D) and two-dimensional (2D) superlattices. However, the construction of one-dimensional (1D) QD superstructures, which have a simpler arrangement, is challenging; therefore, the photophysical properties of 1D-arranged QDs have not been studied previously. Herein, we report a versatile strategy to obtain 1D-arranged QDs using a supramolecular polymer (SP) template. The SP is composed of self-assembling cholesterol derivatives containing two amide groups for hydrogen bonding and a carboxyl group as an adhesion moiety on the QDs. Upon mixing the SP and dispersed QDs in low-polarity solvents, the QDs self-adhered to the SP and self-arranged into 1D superstructures through van der Waals interactions between the surface organic ligands of the QDs, as confirmed by transmission electron microscopy. Furthermore, we revealed efficient photoinduced fluorescence resonance energy transfer between the 1D-arranged QDs by an in-depth analysis of the emission spectra and decay curves. 相似文献
83.
Tom A. J. Welling Sina Sadighikia Kanako Watanabe Albert Grau-Carbonell Maarten Bransen Daisuke Nagao Alfons van Blaaderen Marijn A. van Huis 《Particle & Particle Systems Characterization》2020,37(6):2000003
In theory, liquid-cell (scanning) transmission electron microscopy (LC(S)TEM) is the ideal method to measure 3D diffusion of nanoparticles (NPs) on a single particle level, beyond the capabilities of optical methods. However, particle diffusion experiments have been especially hard to explain in LC(S)TEM as the observed motion thus far has been slower than theoretical predictions by 3–8 orders of magnitude due to electron beam effects. Here, direct experimental evidence of undamped diffusion for two systems is shown; charge-neutral 77 nm gold nanoparticles in glycerol and negatively charged 350 nm titania particles in glycerol carbonate. The high viscosities of the used media and a low electron dose rate allow observation of Brownian motion that is not significantly altered by the electron beam. The resulting diffusion coefficient agrees excellently with a theoretical value assuming free diffusion. It is confirmed that the particles are also moving in the direction parallel to the electron beam by simulating STEM images using Monte Carlo simulations. Simulations and experiments show blurring of the particles when these move out of focus. These results make clear that direct observation of 3D diffusion of NPs is possible, which is of critical importance for the study of interparticle interactions or in situ colloidal self-assembly using LC(S)TEM. 相似文献
84.
Ishii Takahiro Matayoshi Natsuki Taba Kanako Kamada Takashi 《Chemistry of Natural Compounds》2022,58(3):474-477
Chemistry of Natural Compounds - Plectranthus barbatus Andrews is one of the traditional herbs growing in the Okinawa region, Japan. This plant has high nutritional value and is well known... 相似文献
85.
Sekimoto K Sakai M Takayama M 《Journal of the American Society for Mass Spectrometry》2012,23(6):1109-1119
The interaction between negative atmospheric ions and various types of organic compounds were investigated using atmospheric
pressure corona discharge ionization (APCDI) mass spectrometry. Atmospheric negative ions such as O2–, HCO3–, COO–(COOH), NO2–, NO3–, and NO3–(HNO3) having different proton affinities served as the reactant ions for analyte ionization in APCDI in negative-ion mode. The
individual atmospheric ions specifically ionized aliphatic and aromatic compounds with various functional groups as atmospheric
ion adducts and deprotonated analytes. The formation of the atmospheric ion adducts under certain discharge conditions is
most likely attributable to the affinity between the analyte and atmospheric ion and the concentration of the atmospheric
ion produced under these conditions. The deprotonated analytes, in contrast, were generated from the adducts of the atmospheric
ions with higher proton affinity attributable to efficient proton abstraction from the analyte by the atmospheric ion. 相似文献
86.
Yoshiaki Ohgo Kanako Ishida Yoshito Hiraga Yoshifusa Arai Seiji Takeuchi 《Journal of organometallic chemistry》2006,691(10):2319-2326
Solid state-specific and chiral lattice-controlled asymmetric photoisomerization of 3-cyanopropyl cobaloxime complexes coordinated with chiral axial ligand, 1a-h, was found to occur with moderate to relatively high enantioselectivities (∼91%ee), even though the reaction proceeds through radical species. The enantioselectivities at a lower temperature (−78 °C) are extremely enhanced as compared to those at room temperature, in most cases.The configuration of the major enantiomer of the isomerized product is predictable from the shape of the reaction cavity, drawn based on the crystal structure of the starting material. The structure (including absolute configuration) of the intermediate 2-cyanopropyl complex was directly observed by X-ray crystallographic analyses of a single-crystal-to-single-crystal reaction of (S)-1-cyclohexylethylamine-coordinated 3-cyanopropyl cobaloxime, 1e. 相似文献
87.
Kanako Kaihara Toyomi Kotaki Hideharu Numata Yasufumi Ohfune Tetsuro Shinada 《Tetrahedron》2012,68(1):106-113
The structure–activity relationship of JHSB3 isolated from the pentatomid bug, Plautia stali, was studied. Various synthetic analogs were synthesized and subjected to the juvenilizing activity tests using the last instar nymphs of P. stali. These studies indicated that the coexistence of the ester carbonyl group, two epoxides at C2,3 and C10,11 were proved to be crucial for the potent juvenilizing activity. Among the tested analogs, we found highly potent analogs in which the C6,7 double bond of JHSB3 was saturated (0.1 μg/insect). The methoxy analogs in which the epoxide moiety at C10,11 was substituted with a methoxy group exerted a moderate juvenilizing activity. 相似文献
88.
Prof. Tomoaki Tanase Mio Chikanishi Konomi Morita Dr. Kanako Nakamae Dr. Bunsho Kure Prof. Takayuki Nakajima 《化学:亚洲杂志》2015,10(12):2619-2623
A new linear hexaphosphine, rac‐cis,cis,trans‐ bis{[(diphenylphosphinomethyl)phenylphosphinomethyl]phenylphosphino}methane ( P6 ), was synthesized and isolated as a pure isomer, confirmed by transforming to the corresponding phosphine sulfide. The methylene‐bridged linear hexaphosphine readily organized flexible gold(I) and silver(I) hexanuclear chains, [M6(μ‐ P6 )2]X6 (X6=(OTf)6, M=Au ( 1 ), Ag ( 2 ); X6=Cl2(PF6)4, M=Au ( 3 )). The hexaphosphine also supported a tetrasilver(I) complex [Ag4(μ‐ P6 )2](OTf)4 ( 4 ), which was readily transformed by treatment with AgOTf into 3 , revealing a drastic alternation of the two P6 arrangement. The hexagold(I) chains exhibited a considerably red‐shifted absorption (~410 nm) and emission (540–580 nm) to 1[5dσ*→6pσ] and from 3[5dσ*→6pσ] excited states of the metal centers, respectively. The new linear hexaphosphine could be a useful tool to construct linear metal clusters as subnano building blocks. 相似文献
89.
Dr. Naruyoshi Komiya Dr. Minoru Okada Kanako Fukumoto Kenji Kaneta Atsushi Yoshida Prof. Takeshi Naota 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(15):4798-4811
The synthesis, structure, and solid‐state emission of vaulted trans‐bis(salicylaldiminato)platinum(II) complexes are described. A series of polymethylene ( 1 : n=8; 2 : n=9; 3 : n=10; 4 : n=11; 5 : n=12; 6 : n=13) and polyoxyethylene ( 7 : m=2; 8 : m=3; 9 : m=4) vaulted complexes (R=H ( a ), 3‐MeO ( b ), 4‐MeO ( c ), 5‐MeO ( d ), 6‐MeO ( e ), 4‐CF3O ( f ), 5‐CF3O ( g )) was prepared by treating [PtCl2(CH3CN)2] with the corresponding N,N′‐bis(salicylidene)‐1,ω‐alkanediamines. The trans coordination, vaulted structures, and the crystal packing of 1 – 9 have been unequivocally established from X‐ray diffraction studies. Unpredictable, structure‐dependent phosphorescent emission has been observed for crystals of the complexes under UV excitation at ambient temperature, whereas these complexes are entirely nonemissive in the solution state under the same conditions. The long‐linked complex crystals 4 – 6 , 8 , and 9 exhibit intense emission (Φ77K=0.22–0.88) at 77 K, whereas short‐linked complexes 1 – 3 and 7 are non‐ or slightly emissive at the same temperature (Φ77K<0.01–0.18). At 298 K, some of the long‐linked crystals, 4 a , 4 b , 5 c , 5 e , 6 c , 6 e , and 9 b , completely lose their high‐emission properties with elevation of the temperature (Φ298K<0.01–0.02), whereas the other long‐linked crystals, 5 a , 6 a , 9 a , and 9 d , exhibit high heat resistance towards emission decay with increasing temperature (Φ298K=0.21–0.38). Chromogenic control of solid‐state emission over the range of 98 nm can be performed simply by introducing MeO groups at different positions on the aromatic rings. Orange, yellow‐green, red, and yellow emissions are observed in the glass and crystalline state upon 3‐, 4‐, 5‐, and 6‐MeO substitution, respectively, whereas those with CF3O substituents have orange emission, irrespective of the substitution position. DFT calculations (B3LYP/6‐31G*, LanL2DZ) showed that such chromatic variation is ascribed to the position‐specific influence of the substituents on the highest‐occupied molecular orbital (HOMO) and lowest‐unoccupied molecular orbital (LUMO) levels of the trans‐bis(salicylaldiminato)platinum(II) platform. The solid‐state emission and its heat resistance have been discussed on the basis of X‐ray diffraction studies. The planarity of the trans‐coordination sites is strongly correlated to the solid‐state emission intensities of crystals 1 – 9 at lower temperatures. The specific heat‐resistance properties shown exclusively by the 5 a , 6 a , 9 a , and 9 d crystals are due to their strong three‐dimensional hydrogen‐bonding interactions and/or Pt???Pt contacts, whereas heat‐quenchable crystals 4 a , 4 b , 5 c , 5 e , 6 c , 6 e , and 9 b are poorly bound with limited interactions, such as non‐, one‐, or two‐dimensional hydrogen‐bonding networks. These results lead to the conclusion that Pt???Pt contacts are an important factor in the heat resistance of solid‐state phosphorescence at ambient temperature, although the role of Pt???Pt contacts can be substituted by only higher‐ordered hydrogen‐bonding fixation. 相似文献
90.
An analytical method for determining bromate in drinking water was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The (18)O-enriched bromate was used as an internal standard. The limit of quantification (LOQ) of bromate was 0.2 μg/L. The peak of bromate was separated from those of coexisting ions (i.e., chloride, nitrate and sulfate). The relative and absolute recoveries of bromate in two drinking water samples and in a synthesized ion solution (100 mg/L chloride, 10 mg N/L nitrate, and 100 mg/L sulfate) were 99-105 and 94-105%, respectively. Bromate concentrations in 11 drinking water samples determined by LC-MS/MS were <0.2-2.3 μg/L. The results of the present study indicated that the proposed method was suitable for determining bromate concentrations in drinking water without sample pretreatment. 相似文献