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101.
Proton pump inhibitors (PPIs) are benzimidazole-derivative chiral sulfoxides, frequently used in the treatment of gastric hyperacidity-related disorders. Due to their stereoselective metabolism, the eutomeric forms of PPIs can present a more advantageous pharmacokinetic profile by comparison with the distomers or racemates. Moreover, two representatives of the class are used in therapy both as racemates and as pure enantiomers (esomeprazole, dexlansoprazole). A relatively large number of enantioseparation methods employed for the stereoselective determination of PPIs from pharmaceutical, biological, and environmental matrices were published in the past three decades. The purpose of the current overview is to provide a systematic survey of the available chiral separation methods published since the introduction of PPIs in the therapy up to the present. Analytical and bioanalytical methods using different chromatographic and electromigration techniques reported for the enantioseparation of omeprazole, lansoprazole, pantoprazole, rabeprazole, ilaprazole, and tenatoprazole are included. The analytical conditions of the presented methods are summarized in three comprehensive tables, while a critical discussion of the applied techniques, possible mechanism of enantiorecognition, and future perspectives on the topic are also presented. 相似文献
102.
Dr. Isabel Fuentes Dr. María José Mostazo-López Dr. Zsolt Kelemen Prof. Dr. Vicente Compañ Dr. Andreu Andrio Prof. Dr. Emilia Morallón Prof. Dr. Diego Cazorla-Amorós Prof. Dr. Clara Viñas Prof. Dr. Francesc Teixidor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(63):14308-14319
Conducting organic polymers (COPs) are made of a conjugated polymer backbone supporting a certain degree of oxidation. These positive charges are compensated by the doping anions that are introduced into the polymer synthesis along with their accompanying cations. In this work, the influence of these cations on the stoichiometry and physicochemical properties of the resulting COPs have been investigated, something that has previously been overlooked, but, as here proven, is highly relevant. As the doping anion, metallacarborane [Co(C2B9H11)2]− was chosen, which acts as a thistle. This anion binds to the accompanying cation with a distinct strength. If the binding strength is weak, the doping anion is more prone to compensate the positive charge of the polymer, and the opposite is also true. Thus, the ability of the doping anion to compensate the positive charges of the polymer can be tuned, and this determines the stoichiometry of the polymer. As the polymer, PEDOT was studied, whereas Cs+, Na+, K+, Li+, and H+ as cations. Notably, with the [Co(C2B9H11)2]− anions, these cations are grouped into two sets, Cs+ and H+ in one and Na+, K+, and Li+ in the second, according to the stoichiometry of the COPs: 2:1 EDOT/[Co(C2B9H11)2]− for Cs+ and H+, and 3:1 EDOT/[Co(C2B9H11)2]− for Na+, K+, and Li+. The distinct stoichiometries are manifested in the physicochemical properties of the COPs, namely in the electrochemical response, electronic conductivity, ionic conductivity, and capacitance. 相似文献
103.
104.
Dóra Kelemen Dr. Nóra V. May Dr. Melinda Andrási Prof. Attila Gáspár Prof. István Fábián Dr. Norbert Lihi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(70):16767-16773
Detailed equilibrium, spectroscopic and superoxide dismutase (SOD) activity studies are reported on a nickel complex formed with a new metallopeptide bearing two nickel binding loops of NiSOD. The metallopeptide exhibits unique nickel binding ability and the binuclear complex is a major species with 2×(NH2,Namide,S−,S−) donor set even in an equimolar solution of the metal ion and the ligand. Nickel(III) species were generated by oxidizing the NiII complexes with KO2 and the coordination modes were identified by EPR spectroscopy. The binuclear complex formed with the binding motifs exhibits superior SOD activity, in this respect it is an excellent model of the native NiSOD enzyme. A detailed kinetic model is postulated that incorporates spontaneous decomposition of the superoxide ion, the dismutation cycle and fast redox degradation of the binuclear complex. The latter process leads to the elimination of the SOD activity. A unique feature of this system is that the NiIII form of the catalyst rapidly accumulates in the dismutation cycle and simultaneously the NiII form becomes a minor species. 相似文献
105.
Abhishek Koner Gregor Pfeifer Dr. Zsolt Kelemen Dr. Gregor Schnakenburg Prof. Dr. László Nyulászi Prof. Dr. Takahiro Sasamori Prof. Dr. Rainer Streubel 《Angewandte Chemie (International ed. in English)》2017,56(31):9231-9235
1,4-Diphosphinines that are fused to two thiourea units were synthesized from the corresponding tricyclic 1,4-dichloro-1,4-dihydro-1,4-diphosphinines, and their structures and spectroscopic features are described. Electrochemical studies revealed very low oxidation potentials, which are due to the effective π-interaction between the 1,4-diphosphinine ring and the orbitals of the two ylidic C=S bonds. In accordance with the low-lying LUMO, which is largely localized at the two phosphorus centers, dianion formation is strongly preferred. Despite the small HOMO–LUMO gap, which is in accordance with the red color of the title compounds, theoretical calculations suggest considerable aromaticity for the 1,4-diphosphinine ring. 相似文献
106.
Magdalyna Ignatovych Vadym Holovey Andrea Watterich Tams Vidczy Pter Baranyai Andrs Kelemen Oleksij Chuiko 《Radiation measurements》2004,38(4-6):567-570
Photoluminescence, radioluminescence as well as optical absorption techniques were used to characterize Cu- and Eu-doped lithium tetraborate. The effect of host modification (single crystal and glassy state) and a limited range of dopant content were investigated. Time-resolved measurements were helpful to identify the emitting species. 相似文献
107.
Soloviev VY McGinty J Tahir KB Neil MA Sardini A Hajnal JV Arridge SR French PM 《Optics letters》2007,32(14):2034-2036
We present a novel fluorescence lifetime tomography system applied to a highly scattering autofluorescent phantom containing live cells expressing the fluorophore enhanced green fluorescent protein (EGFP). The fluorescence signal was excited using a fiber-laser-pumped supercontinuum source and detected using wide-field time gating imaging. To facilitate rapid 3D reconstruction of the fluorescence lifetime distribution, the time-resolved data were Fourier-transformed in time to give complex functions that formed a data set for the Fourier domain reconstruction. Initially the presence of an unspecified background autofluorescence signal impeded reconstruction of the lifetime distribution, but we show that this problem can be addressed using a simple iterative technique. 相似文献
108.
109.
The thermal conductivity and thermal diffusivity of thexFe2O3 · (1–x) [3 B2O3 · PbO] glasses containing 0, 5, 15, 25, 35 and 50 mol % Fe2O3 were studied. Measurements were performed at temperatures ranging from 100 to 450 K. From the results obtained for thermal conductivity and diffusivity the specific heats of samples were calculated and comparated with those obtained from the additive rules. Our results do not prove the validity of the additive rules. The observed deviations were assigned to structural factors. By using the approximation of the Debye model the average sound velocity, the mean free path and dominant angular frequency of phonon have been calculated. The deviation of phonon mean free path from the average value as a function density fluctuations of the samples was discussed. 相似文献
110.
A. Kelemen 《Nuclear Physics A》1974,220(2):391-394
A method is presented which guarantees the convergence of the solution of HF equations. 相似文献