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Alice Merca Jürgen Schnack Joris van Slageren Thorsten Glaser Hartmut Bögge Veronika Hoeke Mechtild Läge Achim Müller Bernt Krebs 《Journal of Cluster Science》2013,24(4):979-988
The gadolinium (Gd) member of a new type of heteropolytungstates that contain one lanthanide and two transition metal ions in a triangular arrangement is reported. The compound NaK6Gd0.33 [((VO)2Gd(H2O)4K2(H2O)2(Na)(H2O)2)(α-B-AsW9O33)2]·24H2O (1) was prepared from acidified aqueous solutions of Na2WO4·2H2O, As2O3 and VOSO4·5H2O to which Gd3+ ions were added. The single crystal X-ray structure analysis (monoclinic, space group P21/m) shows that the anion consists of two [α-B-AsIIIW9O33]9? trilacunary Keggin-type units linked by two VO2+, one Gd3+ as well as weakly by two K+ and one Na+ ions, resulting in a sandwich-type structure with idealized C 2v symmetry. The problem of positioning crystal lattice and special polyoxometalate sites with different cations is discussed also in connection with supramolecular chemistry aspects and as an option for further research. A fit of the magnetic susceptibility yielded exchange coupling constants of J VV = ?2.55 cm?1 (anti-ferromagnetic) between the vanadium ions and J GdV = 0.6 cm?1 (ferromagnetic) between the Gd and each of the two vanadium ions. The complete magnetochemical analysis also revealed a partial occupancy of the Na+ sites in the counter-cation–water system by Gd3+ ions (0.33 Gd3+ ions in total). 相似文献
94.
Thorsten Will Michael C. Hutter Johann Jauch Volkhard Helms 《Journal of computational chemistry》2013,34(28):2485-2492
Besides all their conformational degrees of freedom, drug‐like molecules and natural products often also undergo tautomeric interconversions. Compared to the huge efforts made in experimental investigation of tautomerism, open and free algorithmic solutions for prototropic tautomer generation are surprisingly rare. The few freely available software packages limit their output to a subset of the possible configurational space by sometimes unwanted prior assumptions and complete neglection of ring‐chain tautomerism. Here, we describe an adjustable fully automatic tautomer enumeration approach, which is freely available and also incorporates the detection of ring‐chain variants. The algorithm is implemented in the MolTPC framework and accessible on SourceForge. © 2013 Wiley Periodicals, Inc. 相似文献
95.
Gregor Lemanski Thorsten Lindenberg Hassan Fakhrnabavi Thomas Ziegler 《Journal of carbohydrate chemistry》2013,32(6):727-745
ABSTRACT Acetyl protected 1,2-O-(1-methoxyethylidene)-disaccharides 1 of maltose, cellobiose, and lactose, respectively were converted via the corresponding benzyl protected couterparts 2, the benzyl protected phenyl 2-O-acetyl- 3 and 2-O-unprotected 1-thio-glycoside disaccharides 4 into 2-O-succinoylated disaccharides 5. The latter were esterified with benzyl 2-O-benzoyl-4,6-di-O-benzylidene-α-D-glucopyranoside (6) to afford succinyl linked derivatives 7 the benzylidene groups of which were regioselectively opened to give prearranged glycoside trisaccharides 8. Intramolecular glycosylation of the latter with N-iodosuccinimide resulted in exclusive formation of the corresponding α-(1→4)-linked trisaccharides 9. No influence of the donor moiety on the diastereoselectivity of the intramolecular glycosylation was observed. 相似文献
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97.
Béatrice D. Leca-Bouvier Audrey Sassolas Loïc J. Blum 《Analytical and bioanalytical chemistry》2014,406(23):5657-5667
This paper reports on electrochemiluminescent sensors and biosensors based on polyluminol/hydrogel composite sensing layers using chemical or biological membranes as hydrogel matrices. In this work, luminol is electropolymerized under near-neutral conditions onto screen-printed electrode (SPE)-supported hydrogel films. The working electrode coated with a hydrogel film is soaked in a solution containing monomeric luminol units, allowing the monomeric luminol units to diffuse inside the porous matrix to the electrode surface where they are electropolymerized by cyclic voltammetry (CV). Sensors and enzymatic biosensors for H2O2 and choline detection, respectively, have been developed, using choline oxidase (ChOD) as a model enzyme. In this case, hydrogel is used both as the enzymatic immobilization matrix and as a template for the electrosynthesis of polyluminol. The enzyme was immobilized by entrapment in the gel matrix during its formation before electropolymerization of the monomer. Several parameters have been optimized in terms of polymerization conditions, enzyme loading, and average pore size. Using calcium alginate or tetramethoxysilane (TMOS)-based silica as porous matrix, H2O2 and choline detection are reported down to micromolar concentrations with three orders of magnitude wide dynamic ranges starting from 4?×?10?7 M. Polyluminol/hydrogel composites appear as suitable electrochemiluminescence (ECL)-active sensing layers for the design of new reagentless and disposable easy-to-use optical sensors and biosensors, using conventional TMOS-based silica gel or the more original and easier to handle calcium alginate, reported here for the first time in such a configuration, as the biocompatible hydrogel matrix. Figure
Elaboration of electrochemiluminent polyluminol/hydrogel composite sensing layers 相似文献
98.
Stephan Brox Axel P. Ritter Eberhard Küster Thorsten Reemtsma 《Analytical and bioanalytical chemistry》2014,406(20):4831-4840
An analytical method using high-performance liquid chromatography–tandem mass spectrometry was developed to determine internal concentrations of 34 test compounds such as pharmaceuticals and pesticides in zebrafish embryos (ZFE), among them, cimetidine, 2,4-dichlorophenoxyacetic acid, metoprolol, atropine and phenytoin. For qualification and quantification, multiple reaction monitoring mode was used. The linear range extends from 0.075 ng/mL for thiacloprid and metazachlor and 7.5 ng/mL for coniine and clofibrate to 250 ng/mL for many of the test compounds. Matrix effects were strongest for nicotine, but never exceeded ±20 % for any of the developmental stages of the ZFE. Method recoveries ranged from 90 to 110 % from an analysis of nine pooled ZFE. These findings together with the simple sample preparation mean this approach is suitable for the determination of internal concentrations from only nine individual ZFE in all life stages up to 96 h post-fertilization. Exemplarily, the time course of the internal concentrations of clofibric acid, metribuzin and benzocaine in ZFE was studied over 96 h, and three different patterns were distinguished, on the basis of the speed and extent of uptake and whether or not a steady state was reached. Decreasing internal concentrations may be due to metabolism in the ZFE. Figure
Quantification of polar pollutants in different life stages of the zebrafish embryo by LC-MS/MS 相似文献
99.
Motivated by the high potential of shape memory alloys (SMA) in several industrial applications, we investigate the material response under cyclic loading. In particular, the focus is set on the modelling of functional fatigue, which results in the deterioration of the specific features of SMA. In fact, functional fatigue restricts SMA in terms of its applicability for real structures and workpieces. This necessitates the development of material models which take this phenomenon into account. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
100.
Dennis Schnfeld Dilip Chalissery Franziska Wenz Marius Specht Chris Eberl Thorsten Pretsch 《Molecules (Basel, Switzerland)》2021,26(3)
For soft robotics and programmable metamaterials, novel approaches are required enabling the design of highly integrated thermoresponsive actuating systems. In the concept presented here, the necessary functional component was obtained by polymer syntheses. First, poly(1,10-decylene adipate) diol (PDA) with a number average molecular weight Mn of 3290 g·mol−1 was synthesized from 1,10-decanediol and adipic acid. Afterward, the PDA was brought to reaction with 4,4′-diphenylmethane diisocyanate and 1,4-butanediol. The resulting polyester urethane (PEU) was processed to the filament, and samples were additively manufactured by fused-filament fabrication. After thermomechanical treatment, the PEU reliably actuated under stress-free conditions by expanding on cooling and shrinking on heating with a maximum thermoreversible strain of 16.1%. Actuation stabilized at 12.2%, as verified in a measurement comprising 100 heating-cooling cycles. By adding an actuator element to a gripper system, a hen’s egg could be picked up, safely transported and deposited. Finally, one actuator element each was built into two types of unit cells for programmable materials, thus enabling the design of temperature-dependent behavior. The approaches are expected to open up new opportunities, e.g., in the fields of soft robotics and shape morphing. 相似文献