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1.
Hideyasu China Nami Kageyama Hotaka Yatabe Naoko Takenaga Toshifumi Dohi 《Molecules (Basel, Switzerland)》2021,26(7)
We report a convenient and practical method for the preparation of nonexplosive cyclic hypervalent iodine(III) oxidants as efficient organocatalysts and reagents for various reactions using Oxone® in aqueous solution under mild conditions at room temperature. The thus obtained 2-iodosobenzoic acids (IBAs) could be used as precursors of other cyclic organoiodine(III) derivatives by the solvolytic derivatization of the hydroxy group under mild conditions of 80 °C or lower temperature. These sequential procedures are highly reliable to selectively afford cyclic hypervalent iodine compounds in excellent yields without contamination by hazardous pentavalent iodine(III) compound. 相似文献
2.
Hidetaka Tsujimoto Hotaka Asuka Shigeru Ikawa Hiroyuki Nakazumi 《Journal of organometallic chemistry》2010,695(17):1972-10838
In order to develop highly emissive red phosphorescent materials for OLED application, novel bis-cyclometalated iridium(III) complexes were developed using the 1-(dibenzo[b,d]furan-4-yl)isoquinolinato-N,C3′ (dbfiq) cyclometalating ligand. When 1,3-bis(3,4-dibutoxyphenyl)propane-1,3-dionate (bdbp) is employed as an ancillary ligand, Ir(dbfiq)2(bdbp) 1 exhibits red photoluminescence (PL) at 640 nm with a quantum yield (ΦPL) of 0.61 (in toluene, 298 K). Replacement of bdbp to dipivaloylmethanate (dpm) and acetylacetonate (acac) (Ir(dbfiq)2(dpm) 2 and Ir(dbfiq)2(acac) 3, respectively) does not affect the PL spectrum, but reduces ΦPL to 0.55 and 0.49 for 2 and 3, respectively. Similar tendency is also found in the doped poly(methyl methacrylate) (PMMA) film, and 1 is more emissive (ΦPL = 0.17) than 2 and 3 (ΦPL = 0.08 and 0.06, respectively). Using 1 as a phosphorescent dopant, polymer light-emitting diodes (PLEDs) were fabricated, of which structure was ITO/PEDOT:PSS (40 nm)/PVCz:1:PBD (100 nm)/CsF (1 nm)/Al (250 nm). Pure red electroluminescence (EL) is obtained from the fabricated PLEDs, affording a CIE chromaticity coordinate of (0.68, 0.31). When 0.51 mol% of 1 is incorporated in the PVCz-based emitting layer, the PLED shows maximum luminance of 7270 cd m−2 at 16.5 V, power efficiency of 1.4 lm W−1 at 7.5 V, and external quantum efficiency of 6.4% at 9.0 V. PLEDs with the same structure and components were also fabricated using 2 and 3, and their device characteristics were investigated. In proportion to the PL quantum yields, 1 affords better device performance than 2 and 3. Owing to four butoxy groups introduced to the bdbp ligand, 1 exhibits high solubility in organic solvents such as chloroform and toluene, and thus, is an excellent red phosphorescent dopant for solution-processed OLEDs. 相似文献
3.
Matsushima S Sasaki F Kinosada Y Maeda H Sogami M Era S Yatabe Y Miura S Ohsaki H Sakamoto J 《Magnetic resonance imaging》2000,18(4):379-385
A prospective study was performed to investigate the correlations between saturation transfer ratio (STR) and histologic parameters of invasive ductal carcinomas in human breast. The histologic parameters investigated were the extent of fibrosis in the intercellular matrix, dysplastic changes of nuclei, and mitotic index. Twenty-seven patients with breast carcinoma were examined using an off-resonance saturation pulse in conjunction with conventional field-echo T(1)-weighted imaging at frequency offsets of 448 Hz and 1200 Hz from water resonance. The values of STR at frequency offset of 1200 Hz (STR(1200)) increased from non-scirrhous carcinoma to scirrhous carcinoma. Although STR(1200) showed correlation with the extent of fibrosis in the intercellular matrix (p<0.01, n = 27), they did not correlate with the dysplastic changes of nuclei or mitotic index. On the other hand, the values of STR at frequency offset of 448 Hz (STR(448)) demonstrated close correlation to dysplastic changes of nuclei and mitotic index (p<0.01, n = 27). STR(1200) correlates with the structural characteristics and STR(448) correlates with the nature of malignant cells with regard to nuclear dysplasia and mitotic potential. 相似文献
4.
Dr. Masaki Yoshida Hotaka Shitama Dr. W. M. C. Sameera Dr. Atsushi Kobayashi Prof. Dr. Masako Kato 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(32):7669-7678
An electrochromic system showing ease of color tunability has been constructed using a triple-decker PtII complex [Pt3(μ3-pydt)2(bpy)3]2+ (H2pydt=2,6-pyridinedithiol, bpy=2,2′-bipyridine). The divalent complex undergoes electrochemically quasi-reversible two-electron transfer coupled with the coordination/dissociation of axial ligands, forming higher valent Pt(+2.67) species [Pt3X2(μ3-pydt)2(bpy)3]2+ (X=Cl−, Br−, and SCN−). These higher valent species exhibit characteristic colors ranging from red to cyan depending on the counter anion X− of the electrolyte. The triple-decker structure provides a novel multicolor electrochromic system with favorable stability and reversibility. Theoretical calculations indicate that the colors of the Pt(+2.67) species are tunable by the trans influence of the axial ligand X−. This novel strategy of post-synthetic color-tuning using triplatinum systems should enable the facile preparation of colorful electrochromic devices without any complicated procedures, which may find application in flexible displays, optical devices, and sensors. 相似文献
5.
The molecular orientation of an aromatic polycarbonate containing fluorene side chains was investigated by polarized infrared spectroscopy and birefringence analyses. The copolymers were synthesized from 2,2‐bis(4‐hydroxyphenyl)propane (BPA), 9,9‐bis(4‐hydroxy‐3‐methylpheny)fluorene (BMPF), and phosgene by interfacial polycondensation. The 1449‐cm?1 band of the uniaxially oriented films, stretched at the glass‐transition temperature (Tg) plus 5 °C, was assigned to various combinations of CC stretching and CH in‐plane bending vibrations in the fluorene ring, and the transition moment angle was estimated to be 90°. The intrinsic birefringence of aromatic polycarbonate films with BMPF molar ratios ranging from 0.5 to 1 was obtained with the 1449‐cm?1 band. The copolymer was estimated to show zero intrinsic birefringence at the BMPF molar ratio of 0.75, and the BMPF homopolymer showed negative intrinsic birefringence. A linear relationship between the volume fraction of BMPF units and the intrinsic birefringence indicated that the two monomer units of BPA and BMPF in each copolymer were not independent, and an intrinsic birefringence could be defined even in the copolymer. The sign of the photoelastic coefficient in the homopolymer with BMPF units was positive. The different signs of the photoelastic coefficient and the intrinsic birefringence suggest that the fluorene side‐chain orientation induced by stress in the glass state is quite different from the orientation of the uniaxially oriented films stretched at Tg + 5 °C. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1554–1562, 2003 相似文献
6.
[Ac-D-Tyr1, D-Ala2, Leu5-OMe]Enkephalin and [Ac-Tyr1, D-Ala2, Leu5-OMe]Enkephalin were successfully synthesized by the coupling of dipeptide units and tripeptide units which were readily obtained by the asymmetric hydrogenation of the corresponding dehydropeptide building blocks. 相似文献
7.
Kawanishi Y Funaki T Yatabe T Suzuki Y Miyamoto S Shimoi Y Abe S 《Inorganic chemistry》2008,47(9):3477-3479
The formation of 1:1 adducts of Pt(bpy)2(2+) (bpy = 2,2'-bipyridine) with various N bases (B) has been ascertained in water at ambient temperature by spectrophotometric titration and electrospray ionization mass spectroscopy. A pseudo-five-coordinated complex, [Pt(bpy)2(B)](2+) with a monodentating bpy, is proposed based on density functional theory calculation. The formation constants (Kc) increase with the nucleophilicity of B except for sterically hindered N-bases, indicating an associative ligand-substitution mechanism. 相似文献
8.
Supported Gold Nanoparticles for Efficient α‐Oxygenation of Secondary and Tertiary Amines into Amides 下载免费PDF全文
Dr. Xiongjie Jin Kengo Kataoka Takafumi Yatabe Dr. Kazuya Yamaguchi Prof. Dr. Noritaka Mizuno 《Angewandte Chemie (International ed. in English)》2016,55(25):7212-7217
Although the α‐oxygenation of amines is a highly attractive method for the synthesis of amides, efficient catalysts suited to a wide range of secondary and tertiary alkyl amines using O2 as the terminal oxidant have no precedent. This report describes a novel, green α‐oxygenation of a wide range of linear and cyclic secondary and tertiary amines mediated by gold nanoparticles supported on alumina (Au/Al2O3). The observed catalysis was truly heterogeneous, and the catalyst could be reused. The present α‐oxygenation utilizes O2 as the terminal oxidant and water as the oxygen atom source of amides. The method generates water as the only theoretical by‐product, which highlights the environmentally benign nature of the present reaction. Additionally, the present α‐oxygenation provides a convenient method for the synthesis of 18O‐labeled amides using H218O as the oxygen source. 相似文献
9.
Satoru Nakai Takafumi Yatabe Kosuke Suzuki Yusuke Sasano Yoshiharu Iwabuchi Jun‐ya Hasegawa Noritaka Mizuno Kazuya Yamaguchi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(46):16804-16812
Methyl‐selective α‐oxygenation of tertiary amines is a highly attractive approach for synthesizing formamides while preserving the amine substrate skeletons. Therefore, the development of efficient catalysts that can advance regioselective α‐oxygenation at the N‐methyl positions using molecular oxygen (O2) as the terminal oxidant is an important subject. In this study, we successfully developed a highly regioselective and efficient aerobic methyl‐selective α‐oxygenation of tertiary amines by employing a Cu/nitroxyl radical catalyst system. The use of moderately hindered nitroxyl radicals, such as 1,5‐dimethyl‐9‐azanoradamantane N‐oxyl (DMN‐AZADO) and 1‐methyl‐2‐azaadamanane N‐oxyl (1‐Me‐AZADO), was very important to promote the oxygenation effectively mainly because these N‐oxyls have longer life‐times than less hindered N‐oxyls. Various types of tertiary N‐methylamines were selectively converted to the corresponding formamides. A plausible reaction mechanism is also discussed on the basis of experimental evidence, together with DFT calculations. The high regioselectivity of this catalyst system stems from steric restriction of the amine‐N‐oxyl interactions. 相似文献
10.
Ruri Hidema Zenji Yatabe Masahiko Shoji Chihiro Hashimoto Robert Pansu Gabriel Sagarzazu Hideharu Ushiki 《Experiments in fluids》2010,49(3):725-732
Two-dimensional turbulence in flowing soap films with polymer additives is analyzed by image analysis. The power spectra of
the interference patterns of turbulent soap films are calculated. The scaling exponent of the power spectrum is −5/3 for polymer
free solution and −1 for dilute polymer solution in enstrophy cascade range, which is consistent with the results of thickness
fluctuations in previous researches. We propose a Curvature analysis method that calculates the curvatures of the interference
pattern of turbulent soap films. The results suggest that the curvature histogram describes well the shape of the interference
pattern, which is related to the shape of the vortices. The curvature histograms for different polymer concentrations can
be fitted by a stretched exponential function. 相似文献