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951.
Jung Hyun Park Faizan Raza Su-Ji Jeon Hye-In KimTae Woog Kang DaBin YimJong-Ho Kim 《Tetrahedron letters》2014
Graphene oxide (GO) was functionalized with a N-heterocyclic carbene (NHC) precursor, 3-(3-aminopropyl)-1-methylimidazolium bromide ([APMIm][Br]) for the immobilization of palladium catalyst. The GO-supported NHC precursor (IMGO) formed a stable complex with Pd(OAc)2 (GO–NHC–Pd), which showed excellent catalytic activity and fast reaction kinetics in the aqueous-phase Suzuki reaction of aryl bromides and chlorides at relatively mild conditions (1 h at 50 °C). The GO–NHC–Pd catalyst was reused several times without any loss of its catalytic activity in the Suzuki reaction of aryl bromide. 相似文献
952.
Eun Joung Choi Eunha Kim Youngjun Lee Ala Jo Seung Bum Park 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(5):1370-1374
Fluorescence imaging enables the uniquely sensitive observation of functional‐ and molecular‐recognition events in living cells. However, only a limited range of biological processes have been subjected to imaging because of the lack of a design strategy and difficulties in the synthesis of biosensors. Herein, we report a facile synthesis of emission‐tunable and predictable Seoul‐Fluors, 9‐aryl‐1,2‐dihydrolopyrrolo[3,4‐b]indolizin‐3‐ones, with various R1 and R2 substituents by coinage‐metal‐catalyzed intramolecular 1,3‐dipolar cycloaddition and subsequent palladium‐mediated C H activation. We also showed that the quantum yields of Seoul‐Fluors are controlled by the electronic nature of the substituents, which influences the extent of photoinduced electron transfer. On the basis of this understanding, we demonstrated our design strategy by the development of a Seoul‐Fluor‐based chemosensor 20 for reactive oxygen species that was not accessible by a previous synthetic route. 相似文献
953.
Tomoki Yoneda Young Mo Sung Jong Min Lim Dongho Kim Atsuhiro Osuka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(48):13385-13389
Reductive metalation of [44]decaphyrin with [Pd2(dba)3] provided a Hückel aromatic [46]decaphyrin PdII complex, which was readily oxidized upon treatment with DDQ to produce a Hückel antiaromatic [44]decaphyrin PdII complex. In CH2Cl2 solution the latter complex underwent slow tautomerization to a Möbius aromatic [44]decaphyrin PdII complex which exists as a mixture of conformers in dynamic equilibrium. To the best of our knowledge, these three PdII complexes represent the largest Hückel aromatic, Hückel antiaromatic, and Möbius aromatic complexes to date. 相似文献
954.
Abdul Wasy Zia Seunghun Lee Jong‐kuk Kim Tae Gyu Kim Jung II Song 《Surface and interface analysis : SIA》2014,46(3):152-156
Diamond‐like carbon (DLC) coatings are getting new trends for cutting tool applications. In this research work, the DLC coatings were deposited on 15 × 15 × 5‐mm tungsten carbide cobalt substrates with variation of bias voltage from 0 to 500 V. The DLC films of 400 nm were deposited using filter cathode vacuum arc system, and 100‐nm chromium interlayer was deposited by sputtering. The optimized conditions for plasma pretreatment at different argon flow rates and deposition rates with bias variation were found. The effect of bias voltage on microstructure, tribology, adhesion, and mechanical properties were evaluated. The characterization techniques employed were field emission electron microscopy, Raman spectroscopy, wear test, SEM, scratch test, and nano‐indentation. The effect of substrate pretreatment on film adhesion was also evaluated. It was observed that etching rate increased with the increase in Ar flow rate while DLC deposition and sputtering rates decreased with increase in the bias voltage. The characterization suggests the DLC coatings deposited at 0 V bias as optimum condition because of showing the best results among all other conditions. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
955.
Hyun Ook Seo Myung‐Geun Jeong Kwang‐Dae Kim Dae Han Kim Young Dok Kim Dong Chan Lim 《Surface and interface analysis : SIA》2014,46(8):544-549
Degradation behaviors of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) layers on NiO in the presence of H2O at ambient pressure and dark conditions were studied using X‐ray photoelectron spectroscopy (XPS). Upon H2O exposure at 120 °C, partial oxidation of P3HT together with molecular water incorporation, but with the maintained local ring‐structure, were deduced by XPS. Valence band spectra of XPS evidenced that the partial oxidation of P3HT local structure could alter π‐conjugation systems of P3HT layers, forming additional electronic states close to its original highest occupied molecular orbital. For comparison, P3HT surface was also exposed to O2, and no change in the S 2p and C 1s spectra was found by O2 exposure at 120 °C, implying that H2O plays a major role at the initial stage of P3HT oxidation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
956.
Jae Cheol Lee Yong Koo Kyoung In Yong Song Jae Woo Lee Young Sik Shin Jin Seok Kim Shin‐ichi Iida 《Surface and interface analysis : SIA》2014,46(7):429-432
We have developed a simple and powerful method, which is called ‘angled sample holder method’, to characterize a topographic structured sample such as microsized via hole of ball grid array using time‐of‐flight SIMS. The diameter of via holes was 100 µm and the depth was 70 µm. To remove the shaded area by incidence primary ion beam and to extract secondary ions from the bottom of a via hole, several types of angled sample holders with compensation steering plate were applied on the basis of simulation results using SIMION code. And the analyses using angled sample holder method enabled us to characterize the bottom and side wall of a via hole in clear. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
957.
Tian Jin Jin-Seok Kim Yu Mu Seok-Hwi Park Xiangdan Jin Jong-Cheol Kang Chang-Young Oh Won-Hun Ham 《Tetrahedron》2014
Total synthesis of methyl l-daunosaminide hydrochloride was achieved from readily available l-tyrosine. Key steps in this strategy were palladium(0) catalyzed stereoselective intramolecular oxazine formation and catalytic hydrogenation of oxazine intermediate. This paper reported 1H and 13C NMR data of α- and β-anomer of methyl l-daunosaminide hydrochloride. 相似文献
958.
A highly environmentally benign protocol for the synthesis of quinazolinones from anthranilamides and aldehydes via aerobic oxidation was developed in wet DMSO. This protocol is operationally simple, exhibits broad substrate scope, and does not need toxic metal catalysts and bases. In addition, the utility of this transformation was further demonstrated by converting the resulting quinazolinones into other useful products in the same-pot without their isolation. 相似文献
959.
Gha-Young Kim Tack-Jin Kim Si-Hyung Kim Seungwoo Paek 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(3):1261-1265
The employment of multiple electrode pairs is one of the ways to achieve a high-throughput electrowinner. In order to improve the U/TRU recovery rate and also to obtain economic advantages for a molten salt electrowinning process, which is a major step in pyroprocessing, the development of an electrode module having a compact structure is required. Here, we designed an anode-liquid cathode module (ALCM), where two graphite anodes are symmetrically arranged centering on a liquid Cd cathode with a mesh stirrer to prevent the growth of U dendrites, to be applied to the electrowinning process. As a preliminary study, basic electrochemical characterization of the designed electrode module was conducted and its capability for U recovery was evaluated in the ALCM-employed lab-scale electrowinner including LiCl–KCl-UCl3 at 500 °C. Also, the morphology and component of the recovered U residue by distillation of the cathode product was examined by FE-SEM and EDS analyses. 相似文献
960.
Haladhara Naik Ashok Goswami Guinyun Kim Kwangsoo Kim Sung-Chul Yang Muhammad Sahid Muhammad Zaman Manwoo Lee Sung-Gyun Shin Moo-Hyun Cho 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1335-1343
The independent isomeric-yield ratios of 89m,gNb for the 93Nb(γ, 4n) 89m,gNb reaction with bremsstrahlung energies of 45-, 50-, 55-, 60-, and 70-MeV were measured by the activation and the off-line γ-ray spectrometric technique at 100 MeV electron linac of the Pohang accelerator laboratory. The isomeric-yield ratios of 89m,gNb for the natZr(p, xn) 89m,gNb and the 89Y(α, 4n) 89m,gNb reactions were measured by using a stacked-foil activation technique with the proton energies of 19–45 MeV and alpha energies of 38.9-, 40.5-, and 42.5-MeV at the MC-50 cyclotron of Korea Institute of Radiological and Medical Sciences. The measured isomeric-yield ratio of 89m,gNb from the 93Nb(γ, 4n), natZr(p, xn), and 89Y(α, 4n) reactions were compared with the similar literature data in the 89Y(3He, 3n) reaction. It was found that the isomeric yield ratio of 89m,gNb increases with projectile energy, which indicate the effect of excitation energy. However, for the similar compound nucleus with the same excitation energy, the isomeric-yield ratios of 89m,gNb in the 89Y(α, 4n) and 89Y(3He, 3n) reactions are higher than those in the 93Nb(γ, 4n) and natZr(p, xn) reactions, which indicates the role of input angular momentum. The isomeric-yield ratios of 89m,gNb in the 93Nb(γ, 4n), natZr(p, xn), 89Y(α, 4n), and 89Y(3He, 3n) reactions were also calculated theoretically using computer code TALYS 1.4. The theoretical isomeric-yield ratios of 89m,gNb from four reactions increase with excitation energy. However, the theoretical value are significantly higher than the experimental data in the 93Nb(γ, 4n) and natZr(p, xn) reactions but slightly lower or comparable in the 89Y(α, 4n) rand 89Y(3He, 3n) reactions. 相似文献