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91.
Albert A. Smith Matthias Ernst Sereina Riniker Beat H. Meier 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9483-9488
Nuclear magnetic resonance (NMR) relaxation data and molecular dynamics (MD) simulations are combined to characterize the dynamics of the fungal prion HET‐s(218‐289) in its amyloid form. NMR data is analyzed with the dynamics detector method, which yields timescale‐specific information. An analogous analysis is performed on MD trajectories. Because specific MD predictions can be verified as agreeing with the NMR data, MD was used for further interpretation of NMR results: for the different timescales, cross‐correlation coefficients were derived to quantify the correlation of the motion between different residues. Short timescales are the result of very local motions, while longer timescales are found for longer‐range correlated motion. Similar trends on ns‐ and μs‐timescales suggest that μs motion in fibrils is the result of motion correlated over many fibril layers. 相似文献
92.
Xiaobo ZhouYunguo Lu Jian-Fa ZhuWing-Hong Chan Albert W.M. LeePui-Shan Chan Ricky N.S. WongN.K. Mak 《Tetrahedron》2011,67(19):3412-3419
By appending a pair of carboxamidoquinoline pendants onto 1,2-diaminocyclohexane scaffold via N-alkylation, multifunctionalized ACAQ was designed and synthesized as a water soluble fluorescent ratiometric chemosensor for Zn2+. In 50% aqueous methanol buffer pH 7.4 solution, upon excitation at 316 nm, ACAQ (5 μM) displayed a selective ratiometric fluorescence changes with a shift from 410 to 490 nm in response to the interaction with Zn2+. After binding with 1 equiv of Zn2+, ACAQ exhibited a 12-fold enhancement in I490/I410 characterized by a clear isoemissive point at 440 nm. The metal sensor binding mode was established by Job’s plot and the combined fluorescence and 1H NMR spectroscopic method. The selectivity of the probe toward biological relevant cations and transition metal ions was proven to be good. In addition, the interference caused by Cu2+ and Cd2+ in the quantitation of Zn2+ can be completely eliminated by the use of diethyldithiocarbamate as the screening agent. Exploitation of ACAQ as the sensing probe, ratiometric determination of Zn2+ with the limit of detection (LOD) at 28.3 nm can be realized. In addition, the unique responsive properties of the probe toward Fe3+ and Zn2+ were used to construct a fluorescent switch. The membrane permeability of ACAQ to living cells and bio-imaging of Zn2+ were demonstrated. 相似文献
93.
Ph. Albert 《Journal of Radioanalytical and Nuclear Chemistry》1980,55(2):453-462
In this article the research topics dealt with at Research Group for Applications of Nuclear Reactions to Chemical Analysis
(GARNAC) are described. Particular emphasis is laid on the main contribution of the GARNAC to the development and the evolution
of charged particle activation analysis, evolving with the analytical studies performed and with the scientific and technical
progress realized in material and semiconductors science.
相似文献
94.
Several new methods for the synthesis of differently substituted 2-amidofurans are described. The thermolysis of furan-2-carbonyl azide results in a Curtius rearrangement and the resulting furanyl isocyanate was trapped with various organometallic reagents. A second method consists of a C-N cross-coupling reaction of a bromo-substituted furan with various amides, carbamates, and lactams. The CuI-catalyzed cross-coupling reaction between furanyl bromides and amides furnished 2- and 3-substituted amidofurans in 45-95% yield. The third protocol used involves the reaction of cyclic carbinol amides with triflic anhydride. The reaction proceeds under very mild conditions to provide alpha-(trifluoromethyl)sulfonamido-substituted furans in high yield. The resulting iminium ion derived from the reaction of the hydroxy pyrrolidinone with Tf(2)O undergoes a facile ring opening as a consequence of the adjacent hydroxyl group to produce an imino triflate intermediate. Subsequent cyclization of this highly electrophilic imine with the oxygen atom of the adjacent carbonyl group leads to an imino dihydrofuran that reacts further with another equivalent of Tf(2)O to give the observed product. 相似文献
95.
Cotton FA Murillo CA Wang X Wilkinson CC 《Dalton transactions (Cambridge, England : 2003)》2007,(35):3943-3951
Six very soluble paddlewheel compounds containing Mo(2)(n+) units, n = 4, 5, 6, and two alkyl-substituted bicyclic guanidinate ligands have been synthesized. The quadruply bonded complexes with n = 4, Mo(2)(TMhpp)(4) and Mo(2)(TEhpp)(4), (TMhpp = the anion of 3,3,9,9-tetramethyl-1,5,7-triazabicyclo[4.4.0]dec-4-ene and TEhpp = the anion of 3,3,9,9-tetraethyl-1,5,7-triazabicyclo[4.4.0]dec-4-ene) are easily oxidized. The electrode potentials in THF are -1.08 and -1.17 V vs. Ag/AgCl, respectively, for the Mo(2)(5+/4+) couple. These potentials are in accord with the low ionization potentials for the quadruply bonded compounds. Because of the high solubility of the Mo(2)(4+) compounds in most common organic solvents they are attractive candidates for use as strong reducing agents in homogeneous systems. 相似文献
96.
The nucleophilic reaction of sodium cellulosate in the form of membrane or cotton fabric with 2, 4-dinitrohalo-benzenes, 2, 4, 6-trinitrochlorobenzene, 2, 4, 6-trinitrobenzyl bromide, and 2, 4, 6-trinitrostyrene was investigated. The degree of substitution attained with the dinitroaryl derivatives was much higher than that with the trinitroaryl derivatives. The reaction proceeded through Meisen-heimer complexes, which in the case of the trinitro derivatives could be isolated. The ability of the polynitro phenyl ether derivatives of the cellulose to form n- and π-complexes was investigated using naphthalene and p-toluidine. No -π- complex was formed with the former, and the latter gave complexes only with the 2, 4, 6-trinitrobenzyl or -phenethyl cellulose derivatives but not with the trinitrophenyl. The results were explained as due to steric hindrance from the polymeric cellulosic backbone. 相似文献
97.
Gideon Fraenkel Albert Chow Yulan Liang Jinhua Song Judith Gallucci 《Helvetica chimica acta》2012,95(11):2063-2071
In a one‐pot process without isolation of intermediates, (but‐3‐en‐1‐yl)pyridine ( 13 ) is treated sequentially with dicyclohexylborane, trimethylaluminium, and ethyl carbonochloridate yielding ethyl 1,4‐dihydro‐4,4‐(tetramethylene)pyridine‐1‐carboxylate (=ethyl 8‐azaspiro[4.5]deca‐6,9‐diene‐8‐carboxylate; 2 ) in 46% yield based on starting alkenylpyridine 13 (Scheme 5). 相似文献
98.
The chiral phosphorus derivatizing agent (CDA) 1 was prepared from optically pure (S)‐1,1‐bis‐2‐naphthol. It was first used in the determination of the enantiomeric excess of chiral alcohols and amines by means of 31P NMR spectroscopy. It showed that, for the chiral aromatic alcohols, no apparent kinetic resolution was noted and good base‐line separation was observed. Furthermore, the chemical shift difference (Δδ) of 31P NMR spectroscopy was much larger than those determined by the use of other chiral phosphorus derivatizing agents reported previously. However, for aliphatic alcohols, it showed not only obvious kinetic resolutions but incomplete base‐line separation. Moreover, we also found that the use of CDA 1 was suitable for the determination of enantiomeric excess of chiral primary amines. © 2002 John Wiley & Sons, Inc. Heteroatom Chem 13:93–95, 2002; DOI 10.1002/hc.10018 相似文献
99.
锌卟啉对氨基酸甲酯手性分子识别的理论研究 总被引:5,自引:0,他引:5
用Tripos力场和分子力学方法研究了手笥锌卟啉的最低能量构象,并用分子动力学模拟了锌卟啉对氨基酸甲酯的识别过程,发现锌卟啉与D-氨基酸酯结合能力强于L-氨基酸,这与热力学实验结果一致. 相似文献
100.
Jian Guo DENG Xiao Bin DING Yu Xing PENG* Albert S. C. CHAN* Chengdu Institute of Organic Chemistry Chinese Academy of Sciences Chengdu Open Laboratory of Chirotechnology Department of Applied Biology Chemical Technology 《中国化学快报》2001,(11)
Among various conducting polymers, polyaniline (PANI) is a unique and promising candidate for practical applications because it is not only highly stable in air and in some solvents, but also exhibits dramatic changes in its electronic structure and physical properties in protoactivate state1,2,3. The carbon nanotubes (CNTs) have been proven to possess exotic properties, such as high mechanical strength, flexibility and electric conductivity. The study of carbon-based nanostructures and ma… 相似文献