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151.
Jan?C.?Myland Keith?B.?OldhamEmail author 《Journal of Solid State Electrochemistry》2014,18(12):3259-3269
The popular inlaid disc electrode suffers from an edge effect that is usually, and sometimes unwarrantedly, ignored in analyzing transient voltammograms. This study addresses the role played by the edge in linear scan and cyclic voltammetries when the electron transfer is reversible or quasi-reversible. A simulation models the concentrations, current densities and currents in two circumstances—when the edge in important and when it is absent—simultaneously, and thereby the evolving edge current is quantified. Special attention is paid to the effect that the edge has on the heights and positions of the voltammetric peaks. It is demonstrated that disregarding the edge may lead to the bogus classification of a reversible electrode reaction as quasi-reversible. 相似文献
152.
D. Thao Nguyen Matthias Freitag Christian Gutheil Dr. Kai Sotthewes Dr. Bonnie J. Tyler Dr. Marcus Böckmann Mowpriya Das Friederike Schlüter Prof. Dr. Nikos L. Doltsinis Prof. Dr. Heinrich F. Arlinghaus Prof. Dr. Bart Jan Ravoo Prof. Dr. Frank Glorius 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13754-13759
153.
Laura Sinatra Jan J. Bandolik Dr. Martin Roatsch Melf Sönnichsen Dr. Clara T. Schoeder Dr. Alexandra Hamacher Andrea Schöler Prof. Dr. Arndt Borkhardt Prof. Dr. Jens Meiler Dr. Sanil Bhatia Prof. Dr. Matthias U. Kassack Prof. Dr. Finn K. Hansen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(50):22681-22687
154.
Dr. Samuel Stolz Dr. Aliaksandr V. Yakutovich Dr. Jan Prinz Dr. Thomas Dienel Dr. Carlo A. Pignedoli Prof. Dr. Harald Brune Dr. Oliver Gröning Dr. Roland Widmer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18336-18340
Enantioselectivity in heterogeneous catalysis strongly depends on the chirality transfer between catalyst surface and all reactants, intermediates, and the product along the reaction pathway. Herein we report the first enantioselective on-surface synthesis of molecular structures from an initial racemic mixture and without the need of enantiopure modifier molecules. The reaction consists of a trimerization via an unidentified bonding motif of prochiral 9-ethynylphenanthrene (9-EP) upon annealing to 500 K on the chiral Pd3-terminated PdGa{111} surfaces into essentially enantiopure, homochiral 9-EP propellers. The observed behavior strongly contrasts the reaction of 9-EP on the chiral Pd1-terminated PdGa{111} surfaces, where 9-EP monomers that are in nearly enantiopure configuration, dimerize without enantiomeric excess. Our findings demonstrate strong chiral recognition and a significant ensemble effect in the PdGa system, hence highlighting the huge potential of chiral intermetallic compounds for enantioselective synthesis and underlining the importance to control the catalytically active sites at the atomic level. 相似文献
155.
Yue Liu Dr. Andy Dang Dr. Jan Urban Prof. Dr. František Tureček 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):7846-7851
Adenosine radicals tagged with a fixed-charge group were generated in the gas phase and structurally characterized by tandem mass spectrometry, deuterium labeling, and UV/Vis action spectroscopy. Experimental results in combination with Born–Oppenheimer molecular dynamics, ab initio, and excited-state calculations led to unambiguous assignment of adenosine radicals as N-7 hydrogen atom adducts. The charge-tagged radicals were found to be electronically equivalent to natural DNA nucleoside radicals. 相似文献
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A new liquid-phase microextraction method based on solidification of floating organic drop 总被引:2,自引:0,他引:2
In the present study, a new and versatile liquid-phase microextraction method is described. This method requires very simple and cheap apparatus and also a small amount of organic solvent. Eight microliters of 1-undecanol was delivered to the surface of solution containing analytes and solution was stirred for a desired time. Then sample vial was cooled by inserting it into an ice bath for 5 min. The solidified 1-undecanol was transferred into a suitable vial and immediately melted; then, 2 μL of it was injected into a gas chromatograph for analysis.Some polycyclic aromatic hydrocarbons (PAHs) were used as model compounds for developing and evaluating of the method performance. Analysis was carried out by gas chromatography/flame ionization detection (GC/FID).Several factors influencing the microextraction efficiency, such as the nature and volume of organic solvent, the temperature and volume of sample solution, stirring rate and extraction time were investigated and optimized. The applicability of the technique was evaluated by determination of trace amounts of PAHs in environmental samples. Under the optimized conditions, the detection limits (LOD) of the method were in the range of 0.07-1.67 μg L−1 and relative standard deviations (R.S.D.) for 10 μg L−1 PAHs were <7%. A good linearity (r2 > 0.995) in a calibration range of 0.25-300.00 μg L−1 was obtained. After 30 min extraction duration, enrichment factors were in the range of 594-1940. Finally, the proposed method was applied to the determination of trace amounts of PAHs in several real water samples, and satisfactory results were resulted. Since very simple devices were used, this new technique is affordable, efficient, and convenient for extraction and determination of low concentrations of PAHs in water samples. 相似文献