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排序方式: 共有243条查询结果,搜索用时 15 毫秒
41.
Wiebke Germer Timo Stalling Uwe Kramer Wolfgang Saak Jürgen Martens 《Heteroatom Chemistry》2014,25(1):20-27
Starting with thiazolines, an important class of heterocyclic imines, a novel rearrangement reaction of corresponding N‐acyliminium ions is described. Furthermore, a new class of heterobicyclic compounds arylated at a single bridgehead atom is obtained diastereospecifically. 相似文献
42.
Jahn S Lohmann W Bomke S Baumann A Karst U 《Analytical and bioanalytical chemistry》2012,402(1):461-471
In the present study, a method for the analysis of reactive metabolites via liquid chromatography (LC) with inductively coupled
plasma–mass spectrometry (MS) was developed. A ferrocenyl-modified glutathione (GSH) reagent, consisting of GSH and succinimidyl-3-ferrocenylpropionate,
was synthesized. Derivatization of the tripeptide was performed at the N-terminus, leaving the nucleophilic thiol group vacant
for the attack of electrophilic compounds. The potential of ferrocenylpropionate (FP)-GSH as a trapping agent for reactive
metabolites was investigated using an electrochemical flow-through cell for metabolism simulation coupled online to a LC system
with electrospray ionization mass spectrometric detection. The pharmaceuticals amodiaquine, an antimalarial agent, and clozapine,
an antipsychotic compound, served as model substances. By proving the successful adduct formation between the reactive metabolite
and ferrocene-labeled GSH, it could be shown that FP-GSH is an effective trapping agent which eases routine reversed-phase
LC analyses. In contrast to GSH, which is usually used for the conjugation of reactive metabolites and where the resulting
adducts often show no or only very little retention, FP-GSH facilitates the detection of the corresponding metabolite adducts
due to higher retention times. 相似文献
43.
Salzmann I Heimel G Duhm S Oehzelt M Pingel P George BM Schnegg A Lips K Blum RP Vollmer A Koch N 《Physical review letters》2012,108(3):035502
Current models for molecular electrical doping of organic semiconductors are found to be at odds with other well-established concepts in that field, like polaron formation. Addressing these inconsistencies for prototypical systems, we present experimental and theoretical evidence for intermolecular hybridization of organic semiconductor and dopant frontier molecular orbitals. Common doping-related observations are attributed to this phenomenon, and controlling the degree of hybridization emerges as a strategy for overcoming the present limitations in the yield of doping-induced charge carriers. 相似文献
44.
TH van der Loop MR Panman S Lotze J Zhang T Vad HJ Bakker WF Sager S Woutersen 《The Journal of chemical physics》2012,137(4):044503
We study the structure and reorientation dynamics of nanometer-sized water droplets inside nonionic reverse micelles (water/Igepal-CO-520/cyclohexane) with time-resolved mid-infrared pump-probe spectroscopy and small angle x-ray scattering. In the time-resolved experiments, we probe the vibrational and orientational dynamics of the O-D bonds of dilute HDO:H(2)O mixtures in Igepal reverse micelles as a function of temperature and micelle size. We find that even small micelles contain a large fraction of water that reorients at the same rate as water in the bulk, which indicates that the polyethylene oxide chains of the surfactant do not penetrate into the water volume. We also observe that the confinement affects the reorientation dynamics of only the first hydration layer. From the temperature dependent surface-water dynamics, we estimate an activation enthalpy for reorientation of 45 ± 9 kJ mol(-1) (11?±?2 kcal mol(-1)), which is close to the activation energy of the reorientation of water molecules in ice. 相似文献
45.
Ohne Zusammenfassung 相似文献
46.
47.
One‐Dimensional Arsenic Allotropes: Polymerization of Yellow Arsenic Inside Single‐Wall Carbon Nanotubes
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Martin Hart Dr. Ji Chen Prof. Angelos Michaelides Prof. Andrea Sella Prof. Milo S. P. Shaffer Dr. Christoph G. Salzmann 《Angewandte Chemie (International ed. in English)》2018,57(36):11649-11653
The pnictogen nanomaterials, including phosphorene and arsenene, display remarkable electronic and chemical properties. Yet, the structural diversity of these main group elements is still poorly explored. Here we fill single‐wall carbon nanotubes with elemental arsenic from the vapor phase. Using electron microscopy, we find chains of highly reactive As4 molecules as well as two new one‐dimensional allotropes of arsenic: a single‐stranded zig‐zag chain and a double‐stranded zig‐zag ladder. These linear structures are important intermediates between the gas‐phase clusters of arsenic and the extended sheets of arsenene. Raman spectroscopy indicates weak electronic interaction between the arsenic and the nanotubes which implies that the formation of the new allotropes is driven primarily by the geometry of the confinement. The relative stabilities of the new arsenic structures are estimated computationally. Band‐gap calculations predict that the insulating As4 chains become semiconducting, once converted to the zig‐zag ladder, and form a fully metallic allotrope of arsenic as the zig‐zag chain. 相似文献
48.
Prof. Dr. Cosima Stubenrauch Dr. Angelika Menner Prof. Alexander Bismarck Dr. Wiebke Drenckhan 《Angewandte Chemie (International ed. in English)》2018,57(32):10024-10032
Emulsions, foams, and foamed emulsions have been used successfully as templates for the synthesis of macroporous polymers. Based on this knowledge this Minireview presents strategies to use, optimise, and upscale these templating methods to synthesise tailor‐made porous polymers. The uniqueness of such polymers lies in the ability to tailor their structures and, therefore, their properties. However, systematic studies on structure–property relations are lacking mainly because the templating scientific community is “split into two”: the polydisperse and monodisperse camps. Thus, it is time to build a bridge between the camps, that is, to synthesise porous polymers with very different structures from the same precursors to determine the relationship between the structure and the properties. 相似文献
49.
An efficient metal-free procedure for the synthesis of tertiary amines by the reductive amination of carbonyl compounds is reported, which allows a convergent access to sterically hindered amines of the general formulas NR(R′)2 and NRR′R″. The mild and operationally simple protocol uses the Hantzsch ester for transfer hydrogenation and catalytic amounts of thiourea for imine activation. 相似文献
50.