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Monatshefte Für Chemie

Edyta Kuliszewska, Friedrich Hammerschmidt
Abstract: Various arylamines were converted in two steps to N-Boc-N-arylphosphoramidates. LiTMP and LDA induced directed ortho-metalation at temperatures from -78 to 0 °C. The ensuing [1,3]-migration of the phosphorus atom with its substituents from the nitrogen to the ortho-carbanionic carbon atom gave N-Boc-protected o-aminoarylphosphonates. The nature of the substituent of 3-substituted phenylphosphoramidates strongly influenced the regioselectivity of phosphonate formation. A crossover experiment with a deuterated phosphoramidate proved the intramolecular course of the rearrangement...
2018: Monatshefte Für Chemie
Clemens Rauer, Juan J Nogueira, Philipp Marquetand, Leticia González
Abstract: Cyclobutane thymine dimerization is the most prominent DNA photoinduced damage. While the ultrafast mechanism that proceeds in the singlet manifold is nowadays well established, the triplet-state pathway is not completely understood. Here we report the underlying mechanism of the photosensitized dimerization process in the triplet state. Quantum chemical calculations, combined with wavefunction analysis, and nonadiabatic molecular dynamics simulations demonstrate that this is a stepwise reaction, traversing a long-lived triplet biradical intermediate, which is characterized as a Frenkel exciton with very small charge-transfer character...
2018: Monatshefte Für Chemie
Marini Damanik, Michael Murkovic
Abstract: A relation between oil uptake and cancer as well as induction of hepatic inflammation was shown earlier. It is discussed that the main oil oxidation products-hydroperoxides and carbonyls-might be the reason for the mentioned diseases. In this manuscript quantitative determination of aldehydes which are formed during oxidation of triolein-as a model substance-using the Rancimat 679 is described. The oxidation of 11 g of triolein is carried out at 120 °C sparging air with a flow of 20 dm3/h for 10 h...
2017: Monatshefte Für Chemie
Marie Stiborová, Radek Indra, Eva Frei, Kateřina Kopečková, Heinz H Schmeiser, Tomáš Eckschlager, Vojtěch Adam, Zbyněk Heger, Volker M Arlt, Václav Martínek
Abstract: Ellipticine is an anticancer agent that forms covalent DNA adducts after enzymatic activation by cytochrome P450 (CYP) enzymes, mainly by CYP3A4. This process is one of the most important ellipticine DNA-damaging mechanisms for its antitumor action. Here, we investigated the efficiencies of human hepatic microsomes and human recombinant CYP3A4 expressed with its reductase, NADPH:CYP oxidoreductase (POR), NADH:cytochrome b5 reductase and/or cytochrome b5 in Supersomes™ to oxidize this drug...
2017: Monatshefte Für Chemie
Václav Martínek, František Bárta, Petr Hodek, Eva Frei, Heinz H Schmeiser, Volker M Arlt, Marie Stiborová
Abstract: The herbal drug aristolochic acid, a natural mixture of 8-methoxy-6-nitrophenanthro[3,4-d]-1,3-dioxole-5-carboxylic acid (AAI) and 6-nitrophenanthro[3,4-d]-1,3-dioxole-5-carboxylic acid (AAII), is derived from Aristolochia species and is the cause of two nephropathies. Ingestion of aristolochic acid is associated with the development of urothelial tumors linked with aristolochic acid nephropathy and is implicated in the development of Balkan endemic nephropathy-associated urothelial tumors...
2017: Monatshefte Für Chemie
Marie Stiborová, Radek Indra, Michaela Moserová, Lucie Bořek-Dohalská, Petr Hodek, Eva Frei, Klaus Kopka, Heinz H Schmeiser, Volker M Arlt
Abstract: Cytochrome P450 (CYP) 1A1 is the most important enzyme activating and detoxifying the human carcinogen benzo[a]pyrene (BaP). In the previous studies, we had shown that not only the canonic NADPH:CYP oxidoreductase (POR) can act as electron donor but also cytochrome b5 and its reductase, NADH:cytochrome b5 reductase. Here, we studied the role of the expression system used on the metabolites generated and the levels of DNA adducts formed by activated BaP. We used an eukaryotic and a prokaryotic cellular system (Supersomes, microsomes isolated from insect cells, and Bactosomes, a membrane fraction of Escherichia coli, each transfected with cDNA of human CYP1A1 and POR)...
2017: Monatshefte Für Chemie
Katarzyna Nalazek-Rudnicka, Andrzej Wasik
ABSTRACT: Biogenic amines are group of organic, basic, nitrogenous compounds that naturally occur in plant, microorganism, and animal organisms. Biogenic amines are mainly produced through decarboxylation of amino acids. They are formed during manufacturing of some kind of food and beverages such as cheese, wine, or beer. Histamine, cadaverine, agmatine, tyramine, putrescine, and β-phenylethylamine are the most common biogenic amines found in wines and beers. This group of compounds can be toxic at high concentrations; therefore, their control is very important...
2017: Monatshefte Für Chemie
Hubert Byliński, Paulina Kolasińska, Tomasz Dymerski, Jacek Gębicki, Jacek Namieśnik
ABSTRACT: Field olfactometry is one of the sensory techniques used to determine odour concentration, in atmospheric air, directly in emission sources. A two-dimensional gas chromatography with time of flight mass spectrometer (GC×GC-TOF-MS) allows performing the chemical characterization of various groups of chemical compounds, even in complex mixtures. Application of these techniques enabled determination of odour concentration level in atmospheric air in a vicinity of the oil refinery and the neighbouring wastewater treatment plant...
2017: Monatshefte Für Chemie
Ewa Jaszczak, Sylwia Narkowicz, Jacek Namieśnik, Żaneta Polkowska
ABSTRACT: Commonly known as a highly toxic chemical, cyanide is also an essential reagent for many industrial processes. It naturally occurs in plant seeds as cyanogenic glycosides. Another relatively common mode of cyanide exposure is inhalation of environmental tobacco smoke. This study concerns importance to determine cyanide ion in human biological samples. Urine and saliva samples were collected healthy volunteers exposed to tobacco smoke (active smokers) and environmental tobacco smoke (passive smokers)...
2017: Monatshefte Für Chemie
Wojciech Wojnowski, Tomasz Majchrzak, Tomasz Dymerski, Jacek Gębicki, Jacek Namieśnik
ABSTRACT: To ensure that chicken meat products are safe to consume, it is important to be able to reliably determine its shelf-life. To assess the applicability of ultra-fast gas chromatography and electronic nose technology in evaluation of poultry, an analysis of the headspace of ground chicken meat samples refrigerated over a period of 7 days was performed. Chemometric techniques were used to mine additional information from a multiparametric data set. As a reference, sensory evaluation was also conducted, and several volatile chemical compounds that can potentially be used as poultry meat decomposition indicators were identified...
2017: Monatshefte Für Chemie
Tomasz Majchrzak, Martyna Lubinska, Anna Różańska, Tomasz Dymerski, Jacek Gębicki, Jacek Namieśnik
ABSTRACT: Oil blending is often used to enhance the properties of vegetable oils. The admixture of a more thermally stable oil makes the resulting blend more suitable for use in frying. A new method of quality assessment of vegetable oils used in frying is presented in this paper. In this method, ultra-fast gas chromatography coupled with flame ionization detector and chemometrics is employed. Principal component analysis was used for data processing. The results obtained with this method were compared with the results of the Rancimat test and sensory evaluation...
2017: Monatshefte Für Chemie
Steffen Kurzhals, Michael Süss, Jelena Pejovic, Peter D J van Oostrum, Erik Reimhult, Ronald Zirbs
ABSTRACT: Crosslinked colloidal monolayers are promising as templates, lithographic masks, filtration membranes, or membranes for controlled release rates in drug delivery. We demonstrate assembly of monodisperse micron-sized polystyrene (PS) beads at an air/water interface, which are transformed into crystalline monolayers using addition of surface-active agents. Vapor annealing methods with solvents (toluene and xylene) and crosslinking agents (divinylbenzene) were investigated regarding their ability to crosslink these floating monolayers directly at the interface, generating crosslinked membranes with crystal size up to 44 cm(2), domain size up to 1...
2017: Monatshefte Für Chemie
Felix Biegger, Felix Jungwirth, Michael Stanislaus Seifner, Christoph Rameshan, Sven Barth
ABSTRACT: Thioether-functionalised indium aminoalcoholates have been used as single-source precursors in aerosol-assisted CVD processes. The obtained In2O3-x S x oxysulphide deposits show either a single indium sulphide phase for deposits with high sulphide content [>75% (S/(S + O)) for the t-butyl derivatives] or pronounced phase separation in indium oxide and indium sulphide for lower sulphide content [<62% (S/(S + O)) for the n-butyl derivatives]. In addition to thin films, polycrystalline 1D structures are obtained at slightly modified synthesis conditions...
2017: Monatshefte Für Chemie
Christine Artner, Ulrich Schubert
ABSTRACT: The carboxylate-substituted mixed-metal oxo clusters Pb6Ti6O9(acetate)(methacrylate)17 and Pb4Ti8O10(OiPr)18(acetate)2 contain a higher number of lead atoms in the cluster core than previously reported compounds. The metal atoms in both clusters are arranged in three layers of different composition, which are connected through oxygen, propionate and/or carboxylate bridges. GRAPHICAL ABSTRACT: HASH(0x4a7ddf8)
2017: Monatshefte Für Chemie
Radomir Jasiński, Karolina Kula, Agnieszka Kącka, Barbara Mirosław
ABSTRACT: Reactions between (E)-2-aryl-1-cyano-1-nitroethenes and diazafluorene lead to acyclic 2,3-diazabuta-1,3-diene derivatives, instead of the expected pyrazoline systems. DFT calculations suggest that this is a consequence of formation of zwitterionic structure in the first stage of the reaction. It must be noted that this is a specific property of the (E)-2-aryl-1-cyano-1-nitroethenes group, in contrast to most other conjugated nitroalkenes. GRAPHICAL ABSTRACT: HASH(0x4a99ac8) ...
2017: Monatshefte Für Chemie
Dominik Farka, H Coskun, P Bauer, D Roth, B Bruckner, Petr Klapetek, N Serdar Sariciftci, P Stadler
ABSTRACT: A stringent limitation in many optoelectronic devices, such as solar cells and light emitting diodes, is the intrinsic need for a transparent electrode. Uniting relevant aspects, indium tin oxide (ITO) is often the material of choice, however, alternatives are sought and being in particular found in conductive polymers. In this work, we present a novel doping strategy to arrive at highly conducting polymeric material based on poly-3,4-ethylenedioxythiophene (PEDOT). Based on commercial high conductivity PEDOT:PSS (Clevios PH 1000), and a post processing with aqueous triflic acid delivers a material that is both transparent and of low resistivity (5...
2017: Monatshefte Für Chemie
Astrid-Caroline Knall, Andrew O F Jones, Birgit Kunert, Roland Resel, David Reishofer, Peter W Zach, Mindaugas Kirkus, Iain McCulloch, Thomas Rath
ABSTRACT: Herein, we describe the synthesis and characterization of a conjugated donor-acceptor copolymer consisting of a pyrrolopyridazinedione (PPD) acceptor unit, and a benzodithiophene (BDT) donor unit. The polymerization was done via a Stille cross-coupling polycondensation. The resulting PPD-BDT copolymer revealed an optical bandgap of 1.8 eV and good processability from chlorobenzene solutions. In an organic solar cell in combination with PC70BM, the polymer led to a power conversion efficiency of 4...
2017: Monatshefte Für Chemie
Sebastian F Hoefler, Gregor Trimmel, Thomas Rath
ABSTRACT: Metal halide perovskites have revolutionized the field of solution-processable photovoltaics. Within just a few years, the power conversion efficiencies of perovskite-based solar cells have been improved significantly to over 20%, which makes them now already comparably efficient to silicon-based photovoltaics. This breakthrough in solution-based photovoltaics, however, has the drawback that these high efficiencies can only be obtained with lead-based perovskites and this will arguably be a substantial hurdle for various applications of perovskite-based photovoltaics and their acceptance in society, even though the amounts of lead in the solar cells are low...
2017: Monatshefte Für Chemie
Dariusz Guziejewski, Sylwia Smarzewska, Radovan Metelka, Agnieszka Nosal-Wiercińska, Witold Ciesielski
ABSTRACT: The use of square wave voltammetry (SWV) and square wave adsorptive stripping voltammetry (SWAdSV) in conjunction with a cyclic renewable silver amalgam film electrode for the determination of flumetralin is presented. Poor separation of two overlapped reduction peaks is significantly improved when hexadecyltrimethylammonium bromide is used as a component of the supporting electrolyte solution (together with BR buffer pH 9.5). The SW technique parameters were investigated and found optimal as follows: frequency 50 Hz, amplitude 40 mV, and step potential 5 mV...
2017: Monatshefte Für Chemie
Mariola Brycht, Agnieszka Nosal-Wiercińska, Karolina Sipa, Konrad Rudnicki, Sławomira Skrzypek
ABSTRACT: In this paper, the square-wave adsorptive stripping voltammetric (SWAdSV) determination of the veterinary drug closantel using a renewable silver amalgam film electrode (Hg(Ag)FE) is presented. As observed in SWAdSV, closantel provided one well-shaped reduction peak suitable for analytical purposes at potential ca. -1.4 V in the Britton-Robinson (B-R) buffer at pH 7.0. At optimal conditions, the SWAdSV response of Hg(Ag)FE for determining closantel was linear over two concentration ranges of 5...
2017: Monatshefte Für Chemie
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