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11.
Thomas Geiger Simon Schundelmeier Thorsten Hummel Dr. Markus Ströbele Dr. Wolfgang Leis Prof. Dr. Michael Seitz Clemens Zeiser Luca Moretti Dr. Margherita Maiuri Prof. Dr. Giulio Cerullo Jun.-Prof. Dr. Katharina Broch Jörn Vahland Prof. Dr. Karl Leo Dr. Cäcilia Maichle-Mössmer Prof. Dr. Bernd Speiser Prof. Dr. Holger F. Bettinger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(15):3420-3434
The properties as well as solid-state structures, singlet fission, and organic field-effect transistor (OFET) performance of three tetrafluoropentacenes (1,4,8,11: 10 , 1,4,9,10: 11 , 2,3,9,10: 12 ) are compared herein. The novel compounds 10 and 11 were synthesized in high purity from the corresponding 6,13-etheno-bridged precursors by reaction with dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate at elevated temperatures. Although most of the molecular properties of the compounds are similar, their chemical reactivity and crystal structures differ considerably. Isomer 10 undergoes the orbital symmetry forbidden thermal [4+4] dimerization, whereas 11 and 12 are much less reactive. The isomers 11 and 12 crystallize in a herringbone motif, but 10 prefers π–π stacking. Although the energy of the first electric dipole-allowed optical transition varies only within 370 cm−1 (0.05 eV) for the neutral compounds, this amounts to roughly 1600 cm−1 (0.20 eV) for radical cations and 1300 cm−1 (0.16 eV) for dications. Transient spectroscopy of films of 11 and 12 reveals singlet-fission time constants (91±11, 73±3 fs, respectively) that are shorter than for pentacene (112±9 fs). OFET devices constructed from 11 and 12 show close to ideal thin-film transistor (TFT) characteristics with electron mobilities of 2×10−3 and 6×10−2 cm2 V−1 s−1, respectively. 相似文献
12.
A simple and robust method was developed for the routine identification and quantification of amoxicillin by micellar LC. Amoxicillin, a beta-lactamase inhibitor, is one of the most commonly prescribed drugs in the treatment of urine and skin structure infections. In this work, amoxicillin was determined in urine samples without any pretreatment step in a phenyl column using a micellar mobile phase of 0.10 M SDS and 4% butanol at pH 3. A UV detection set at 210 nm was used. Amoxicillin was eluted at 5.1 min with no interference by the protein band or endogenous compounds. Linearities (r >0.9998), intra- and interday precisions were determined (RSD (%) 0.4-2.7% and 0.3-5%, respectively, in micellar media, and 0.14-2.6% and 0.13-6%, respectively, in urine), and robustness was studied in the method validation. LOD and LOQ were 0.04 and 0.1 microg/mL in micellar media and 0.14 and 0.34 microg/mL in urine, respectively. Recoveries in the urine matrix were in the range of 95-110%. The validated method proved to be reliable and sensitive for the determination of amoxicillin in urine samples. 相似文献
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Munshi G Mustafa Sudhir Raniwala T Awes B Rai RS Bhalerao JG Contreras RV Gavai SK Ghosh P Jaikumar GC Mishra AP Mishra H Mishra B Mohanty J Nayak J-Y Ollitrault SC Phatak L Ramello R Ray PK Sahu AM Srivastava DK Srivastava VK Tiwari 《Pramana》2006,67(5):961-981
This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and
work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported. 相似文献
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KB McTiernan SC Jarvis D Allen R Bol D Scholefield 《Rapid communications in mass spectrometry : RCM》1999,13(18):1803-1807
The composition of dissolved organic matter (DOM) in a soil is the product of a variety of soil processes. Changes in the composition of DOM in water discharged from soil should, therefore, give an important insight into modifications in these soil processes. We hypothesise that these processes in soils, under different grassland management regimes, would be affected to different extents by the short-term disturbance of a storm event and that evidence of this could be detected in delta(13)C and delta(15)N signatures in drainage and surface runoff waters. During a storm event we collected discharge waters from 1 ha grassland lysimeters, with or without artificial drainage, which received contrasting fertiliser inputs, and delta(13)C and delta(15)N signatures were determined. Changes in (13)C enrichment during the storm event were clearly identifiable, as were differences between plots for (13)C and (15)N, illustrating that this technique has potential to be a useful tool for identifying and investigating short- and long-term changes in soil organic matter dynamics. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
17.
Clemens Zeiser Dr. Luca Moretti Daniel Lepple Prof. Giulio Cerullo Dr. Margherita Maiuri Dr. Katharina Broch 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(45):20141-20148
Heterofission is a photophysical process of fundamental and applied interest whereby an excited singlet state is converted into two triplets on chemically distinct chromophores. The potential of this process lies in the tuning of both the optical band gap and the splitting between singlet and triplet energies. Herein, we report the time-domain observation of heterofission in mixed thin films of the prototypical singlet fission chromophores pentacene and tetracene using excitation wavelengths above and below the tetracene band gap. We found a time constant of 26 ps for endothermic heterofission of a singlet exciton on pentacene in blends with low pentacene fractions, which was outcompeted by pentacene homofission for increasing pentacene concentrations. Direct excitation of tetracene lead to fast energy transfer to pentacene and subsequent singlet fission, which prevented homo- or heterofission of a singlet exciton on tetracene. 相似文献
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Use of micellar liquid chromatography to analyze darunavir,ritonavir, emtricitabine,and tenofovir in plasma
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Juan Peris‐Vicente Mónica Villarreal‐Traver Inmaculada Casas‐Breva Samuel Carda‐Broch Josep Esteve‐Romero 《Journal of separation science》2014,37(20):2825-2832
Danuravir, ritonavir, emtricitabine, and tenofovir are together prescribed against AIDS as a highly active antiretroviral therapy regimen. Micellar liquid chromatography has been applied to determine these four antiretroviral drugs in plasma. The sample preparation is shortened to the dilution of the sample in a micellar solution, filtration, and injection. Clean‐up steps are avoided, due to the solubilization of plasma matrix in micellar media. The drugs were analyzed in <20 min using a mobile phase of 0.06 M sodium dodecyl sulfate/2.5% 1‐pentanol (pH 7) running under isocratic mode through a C18 column at 1 mL/min at room temperature. Absorbance wavelength detection was set at 214 nm. The method was successfully validated following the ICH Harmonized Tripartite Guideline in terms of selectivity, limit of detection (0.080–0.110 μg/mL), limit of quantification (0.240–0.270 μg/mL), linearity between 0.25 and 25 μg/mL (r2 > 0.995), accuracy (89.3–103.2%), precision (<8.2%) and robustness (<7.5%). Real plasma sample from patients taking this therapy were analyzed. This is the first paper showing the simultaneous detection of this four drugs. Therefore, the methodology was proven useful for the routine analysis of these samples in a hospital laboratory for clinical purposes. 相似文献
19.
Holographic phase conjugation is analyzed as a method to create a photo-refractive lens with high numerical aperture. For
this purpose a sub-wavelength hole is drilled into a metal surface directly on top of an iron-doped lithium niobate crystal.
An interference pattern generated by the light coming from this point source and a plane reference wave is recorded. By using
the phase-conjugated reference wave for read-out, a light wave being focused onto the former point source is reconstructed.
In principle, a focusing system close to the theoretical diffraction limit could be implemented by this method. The performance
of this arrangement is mainly determined by properties of the lithium niobate crystal, especially the crystal symmetry. Experimentally,
the tight holographic focusing is demonstrated. The focus width of the reconstructed wave is shown to be below 1.2 μm, which
is our spatial resolution. The diffraction efficiency obtained, however, is just 3×10−5 compared to 3×10−2 in the plane-wave case. This can be explained by experimental reasons, the inhomogeneous light intensity and limitations
originating from the crystal symmetry. We estimate that the diffraction efficiency for phase conjugation through a sub-wavelength
hole can be improved by three to four orders of magnitude by addressing the above-mentioned issues. 相似文献
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