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111.
112.
Tadeusz Jankowski 《Applicable analysis》2013,92(1-2):103-114
The method of quasilinearization is a well-known technique for obtaining approximate solutions of nonlinear differential equations. We use this technique to initial value problems of functional differential equations showing that corresponding linear iterations converge to the unique solution of our problem and this convergence is superlinear 相似文献
113.
Jackowski K Jaszuński M Kamieński B Wilczek M 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,193(1):147-149
We present new gas-phase NMR spectra which relate the resonance frequency of (3)He nucleus to the resonance frequency of the proton in tetramethylsilane (TMS). We discuss the dependence of (3)He resonance frequency on the density of the solvent gas, and we consider in detail the absolute shielding scales of both nuclei. Finally, we analyse the accuracy of the results, using the relationship between the resonance frequencies, absolute shielding constants and magnetic dipole moments of (1)H and (3)He nuclei. 相似文献
114.
Marco Carini Mauro Marongiu Karol Strutyski Akinori Saeki Manuel Melle‐Franco Aurelio Mateo‐Alonso 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):15935-15939
Supramolecular polymers show great potential in the development of new materials because of their inherent recyclability and their self‐healing and stimuli‐responsive properties. Supramolecular conductive polymers are generally obtained by the assembly of individual aromatic molecules into columnar arrays that provide an optimal channel for electronic transport. A new approach is reported to prepare supramolecular polymers by hooking together sigmoidal monomers into 1D arrays of π‐stacked anthracene and acridine units, which gives rise to micrometer‐sized fibrils that show pseudoconductivities in line with other conducting materials. This approach paves the way for the design of new supramolecular polymers constituted by acene derivatives with enhanced excitonic and electronic transporting properties. 相似文献
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Karol Kraszewski Ireneusz Tomczyk Dr. Aneta Drabinska Dr. Krzysztof Bienkowski Dr. Renata Solarska Dr. Marcin Kalek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11584-11592
The oxidative dearomatization of phenols with the addition of nucleophiles to the aromatic ring induced by hypervalent iodine(III) reagents and catalysts has emerged as a highly useful synthetic approach. However, experimental mechanistic studies of this important process have been extremely scarce. In this report, we describe systematic investigations of the dearomatizing hydroxylation of phenols using an array of experimental techniques. Kinetics, EPR spectroscopy, and reactions with radical probes demonstrate that the transformation proceeds by a radical-chain mechanism, with a phenoxyl radical being the key chain-carrying intermediate. Moreover, UV and NMR spectroscopy, high-resolution mass spectrometry, and cyclic voltammetry show that before reacting with the phenoxyl radical, the water molecule becomes activated by the interaction with the iodine(III) center, causing the Umpolung of this formally nucleophilic substrate. The radical-chain mechanism allows the rationalization of all existing observations regarding the iodine(III)-promoted oxidative dearomatization of phenols. 相似文献
117.
Michał Dąbrowski Dr. Przemysław Wyrębek Dr. Damian Trzybiński Prof. Krzysztof Woźniak Prof. Karol Grela 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3782-3794
Robust, selective, and stable in the presence of ethylene, ruthenium olefin metathesis pre-catalyst, {[3-benzyl-1-(10-phenyl-9-phenanthryl)]-2-imidazolidinylidene}dichloro(o-isopropoxyphenylmethylene)ruthenium(II), Ru-3 , bearing an unsymetrical N-heterocyclic carbene (uNHC) ligand, has been synthesized. The initiation rate of Ru-3 was examined by ring-closing metathesis and cross-metathesis reactions with a broad spectrum of olefins, showing an unprecendented selectivity. It was also tested in industrially relevant ethenolysis reactions of olefinic substrates from renewable feedstock with very good yields and selectivities. 相似文献
118.
Tomasz Nienałtowski Paweł Szczepanik Paweł Małecki Dr. Dorota Czajkowska-Szczykowska Dr. Stefan Czarnocki Dr. Jolanta Pawłowska Dr. Anna Kajetanowicz Prof. Karol Grela 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15708-15717
A large-scale synthesis of known Ru olefin metathesis catalyst VII featuring an unsymmetrical N-heterocyclic carbene (NHC) ligand with one 2,5-diisopropylphenyl (DIPP) and one thiophenylmethylene N-substituent is reported. The optimised procedure does not require column chromatography in any step and allows for preparation of up to 0.5 kg batches of the catalyst from simple precursors. The application profile of the obtained catalyst was studied in environmentally friendly dimethyl carbonate (DMC). Although VII exhibited low efficiency in cross-metathesis (CM) with electron-deficient partners, good to excellent results were noted for substrates featuring easy to isomerise C−C double bonds. This includes polyfunctional substrates of medicinal chemistry interest, such as analogues of psychoactive 5F-PB-22 and NM-2201 and two PDE5 inhibitors—Sildenafil and Vardenafil. Finally, a larger scale ring-closing metathesis (RCM) of a Vardenafil derivative was conducted in DMC, allowing for straightforward isolation of the expected product (23 g) in high yield and with low Ru contamination level (7.7 ppm). 相似文献
119.
120.
Monika Müllerová Karol Holý Pavol Blahušiak Martin Bulko 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(2):237-241
The influence of meteorological parameters on radon exhalation rate was analyzed. The analyses show a significant influence of precipitation on radon exhalation rate. The highest exhalation rate was found during dry periods and the lowest during the periods of strong precipitation. We also tested two different types of detectors for the measurement of radon exhalation rate—the ionization chamber (AlphaGUARD) and the scintillation chamber of Lucas type. The exhalation rates measured by these detectors were in a good agreement. Likewise, there was an agreement in radon exhalation rates determined from short term and long term increases in radon activity concentration. 相似文献