TY - JOUR A1 - Wang, Xuebin A1 - Wang, Xiaoli A1 - Hu, Jing A1 - Wang, Zhaoya A1 - Pimpalpalle, Tukaram M. A1 - Linker, Torsten A1 - Yin, Jian T1 - Study on the Synthesis of Novel Sugar Amino Acids T1 - 新型糖氨基酸类化合物的合成研究 JF - Acta chimica Sinica = Huaxue-xuebao N2 - Sugar amino acids (SAAs) are carbohydrate derivatives bearing both amino and carboxylic acid functional groups. SAAs represent an important class of multifunctional building blocks, which are amenable to serve as glycomimetics or peptidomimetics with well-defined structures and useful properties. Because SAAs exist in nature in many forms with various biological activities, recently, many unnatural SAAs, as the demand for finding new molecules to discover new drugs and new materials, have been designed and synthesized by a number of research groups. In this paper, we have developed a convenient method for the synthesis of novel SAAs gluco-7 and galacto-7 for the first time. The structure of gluco-7 was similar to the natural SAA glucosaminuronic acid that was a component of many typical bacterial cell walls and could be used for the preparation of type D flu vaccine; while galacto-7 was similar to the natural SAA galactosaminuronic acid that was one of bacterial Vi-antigen components of Escherichia coli. Starting from unexpensive and commercially available 3,4,6-tri-O-acetyl-D-glucal and 3,4,6-tri-O-acetyl-D-galactal, two novel SAAs gluco-7 and galacto-7 were achieved in the linear 6 steps with 34% overall yield and 19% overall yield, respectively. The key reactions included radical addition, decarboxylation, iodine generation reaction, azide reaction and reductive amination reaction. The crucial step was the synthesis of the target compound gluco-7 from gluco-6. By using method A, the target compound gluco-7 was obtained in 4 steps with 63% overall yield. To optimize the transformation from gluco-6 to gluco-7, method B was developed to generate gluco-7 by using one-pot reaction successfully with 76% yield only in one step. It proved that method B was superior to method A with shorter steps and higher yields. All the new compounds were characterized by IR, H-1 NMR, C-13 NMR and HRMS data. Study on the synthesis and biological evaluation of linear and cyclic oligomers derived from gluco-7 and galacto-7 are currently in progress. KW - sugar amino acids KW - glycal KW - radical addition KW - one-pot reaction KW - synthesis Y1 - 2015 U6 - https://doi.org/10.6023/A15030205 SN - 0567-7351 VL - 73 IS - 7 SP - 699 EP - 704 PB - Science China Press CY - Beijing ER - TY - JOUR A1 - Thomas, Steffen A1 - Kleinpeter, Erich T1 - Zur Zuordnung der 13C-Chemischen Verschiebungen substituierter Naphthaline aus Ladungsdichten mit Hilfe eines neuronalen Netzes Y1 - 1995 ER - TY - JOUR A1 - Hermanns, Jolanda A1 - Schmidt, Bernd T1 - Zur Verwendung von QR-Codes in Uni-Seminaren – ein Baustein in den neu konzipierten Übungen zur Vorlesung „Organische Chemie für Studierende im Nebenfach“ T1 - The use of QR-Codes in university courses - a building block of the newly constructed accompanying exercises for the lecture "organic chemistry" for chemistry minors JF - Chemkon N2 - Die Verwendung von QR-Codes in Begleitseminaren zur Vorlesung „Organische Chemie“ für Studierende mit Chemie im Nebenfach wird vorgestellt. Die Hausaufgaben zu den Seminaren wurden mit einem QR-Code versehen. Dieser führt zu weiterführenden Hilfen. Der Einsatz der QR-Codes sowie die Neukonzeption der Seminare wurden evaluiert. N2 - The use of QR-Codes in university courses for the lecture "Organic Chemistry" for minor students is presented. The homework to the seminars includes a QR-Code. This code leads to supporting learning aids. The use of the QR-Codes as the new concept into seminars is evaluated. KW - graded learning aids KW - homework KW - Chemical exercises KW - QR-Code Y1 - 2017 U6 - https://doi.org/10.1002/ckon.201710300 SN - 0944-5846 SN - 1521-3730 VL - 24 SP - 139 EP - 141 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Ströhl, D. A1 - Kleinpeter, Erich T1 - Zur Stereochemie acyclischer Verbindungen : III. Bestimmung der Vorzugskonformstion unterschiedlich substituirternY-Chlorpropylether Y1 - 1993 ER - TY - JOUR A1 - Breternitz, Joachim A1 - Lehmann, Frederike A1 - Barnett, Sarah A. A1 - Nowell, Harriott A1 - Schorr, Susan T1 - Zur Rolle der Iodid-Methylammonium-Interaktion in der Ferroelektrizität in CH3NH3PbI3 JF - Angewandte Chemie N2 - Ihre außergewöhnlich hohen Konversionseffizienzen von über 20 % und die einfache Zellherstellung machen Hybridperowskite zu heißen Kandidaten für alternative Solarzellenmaterialien. CH3NH3PbI3 als Archetyp dieser Materialklasse besitzt außergewöhnliche Eigenschaften wie eine sehr effiziente Umwandlung von Solarenergie, wobei besonders Ferroelektrizität als mögliche Erklärung in den Fokus gerückt ist. Diese erfordert allerdings eine nicht-zentrosymmetrische Kristallstruktur als notwendige Voraussetzung. Wir stellen hier eine Erklärung des Symmetriebruchs in diesem Material auf kristallographischem, d. h. fernordnungs-basiertem, Wege vor. Während das Molekülkation CH3NH3+ intrinsisch polar ist, ist es extrem fehlgeordnet und kann deshalb nicht die einzige Erklärung darstellen. Es verzerrt allerdings das umgebende Kristallgitter und ruft dadurch eine Verschiebung der Iod-Atome von den zentrosymmetrischen Positionen hervor. KW - ferroelectricity KW - hybrid perovskites KW - inorganic chemistry KW - photovoltaic materials KW - structure elucidation Y1 - 2019 VL - 132 IS - 1 PB - John Wiley & Sons, Inc. CY - New Jersey ER - TY - JOUR A1 - Schmidt, Joachim A1 - Bechmann, Wolfgang T1 - Zur Anwendung des Skalarprodukts von Kraft und Weg auf reversible Prozesse (Druck-Volumen-Änderung, Dehnung, Elektrostatische Wechselwirkung, Hub) T1 - To the application of the scalar product of force and displacement to reversible processes (pressure-volume change, elongation, electrostatic interaction, raising) BT - die Verwendung äußerer oder systemimmanenter Kräfte BT - the use of external or system-immanent forces N2 - Wir schlagen einen allgemein anwendbaren Algorithmus vor, der unter Verwendung des Skalarprodukts von Kraft und Weg zum richtigen Vorzeichen in den Gleichungen für die Arbeit und die Potentielle Energie bei reversiblen Prozessen (Druck-Volumen-Änderung, Dehnung, Elektrostatische Wechselwirkung, Hub)führt. Wir zeigen, dass es dabei möglich ist, systemimmanente oder externe Kräfte zu benutzen. Wir zeigen, dass bei Verwendung von systemimmanenten Kräften das Skalarprodukt mit negativem Vorzeichen anzusetzen ist. Zudem ist es sehr wichtig, nötige Vorzeichenwechsel bei den einzelnen Schritten zu beachten. Wir betonen dies, weil gelegentlich übersehen wird, dass ein Vorzeichenwechsel nötig ist, wenn das Wegdifferential ds durch das Höhendifferential dh beziehungsweise durch das Abstandsdifferential dx oder dr ersetzt werden muss. KW - Skalarprodukt von Kraft und Weg KW - systemimmanente Kräfte KW - Druck-Volumen-Änderung KW - Dehnung KW - Elektrostatische Wechselwirkung KW - Gravitation KW - scalar product of force and displacement KW - system-immanent forces KW - pressure-volume change KW - elongation KW - electrostatic interaction KW - gravitation Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-69732 ER - TY - JOUR A1 - Schröder, Martina A1 - Kümmel, Rolf A1 - Mickler, Wulfhard A1 - Uhlemann, Erhard T1 - Zur Abtrennung von Kupfer aus ammoniakalischer Lösung durch Flüssig-Flüssig-Extraktion und Flüssigmembranpermeation mit 1-Phenyl-3-methyl-4-stearoylpyrazol-5-on Y1 - 1991 ER - TY - JOUR A1 - Koetz, Joachim A1 - Kosmella, Sabine A1 - Kulicke, Werner-Michael A1 - Heinze, Thomas T1 - Zum Einfluss des Lösungszustandes von Carboxymethylcellulosen auf das Strukturbildungsverhalten in kolloidalen Systemen Y1 - 2002 ER - TY - JOUR A1 - Uhlemann, Erhard A1 - Banße, Wolfgang A1 - Ludwig, Eberhard A1 - Mehner, Hartmut A1 - Zeigan, Dieter T1 - Zinn(IV)-Komplexe mit dreizähnigen diaciden Liganden - 119Sn-NMR und 119mSN-Mössbauer- spektroskopische Untersuchungen Y1 - 1994 ER - TY - JOUR A1 - Greue, Th. A1 - Barberka, Thomas Andreas A1 - Pietsch, Ullrich A1 - Stumpe, Joachim A1 - Kauppe, G. T1 - Zeitaufgelöste Untersuchungen an Photochromen LB-Multischichten mittels energiedispersiver Röntgenkleinwinkelstreuung, in-plane Beugung und AFM Y1 - 1995 ER - TY - JOUR A1 - Guiet, Amandine A1 - Unmüssig, Tobias A1 - Göbel, Caren A1 - Vainio, Ulla A1 - Wollgarten, Markus A1 - Driess, Matthias A1 - Schlaad, Helmut A1 - Polte, Jörg A1 - Fischer, Anna T1 - Yolk@Shell Nanoarchitectures with Bimetallic Nanocores - Synthesis and Electrocatalytic Applications JF - Earth & planetary science letters KW - AgAu alloy nanoparticles KW - tin-rich ITO KW - yolk@shell materials KW - nanoreactor KW - soft-templating KW - inverse micelles KW - polystyrene-block-poly(4-vinylpyridine) Y1 - 2016 U6 - https://doi.org/10.1021/acsami.6b06595 SN - 1944-8244 VL - 8 SP - 28019 EP - 28029 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Koch, Andreas T1 - Y-aromaticity - existing: yes or no? An answer given on the magnetic criterion (TSNMRS) JF - Tetrahedron N2 - The spatial magnetic properties (Through Space NMR Shieldings - TSNMRS) of a number of Y-shaped structures possessing 4n+2 pi-electrons (i.a. the trimethylenemethane ions TMM2+, TMM2-, the guanidinium cation, substituted and hetero analogues) have been computed, visualized as Isochemical Shielding Surfaces (ICSS) of various size and direction, were examined subject to present Y-aromaticity and the results compared with energetic and geometric criteria obtained already. (C) 2016 Elsevier Ltd. All rights reserved. KW - Y-aromaticity KW - pi-Electron delocalization KW - Theoretical calculations KW - ICSS KW - TSNMRS Y1 - 2016 U6 - https://doi.org/10.1016/j.tet.2016.02.020 SN - 0040-4020 VL - 72 SP - 1675 EP - 1685 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Gorfman, Semen A1 - Tsirelson, Vladimir A1 - Pucher, Andreas A1 - Morgenroth, Wolfgang A1 - Pietsch, Ullrich T1 - X-ray diffraction by a crystal in a permanent external electric field : electric-field-induced structural response in alpha-GaPO4 N2 - For the first time, site-selective distortion has been investigated for two different structural units in the ternary compound alpha-GaPO4 under the influence of a permanent external electric field. Based on 54 measured reflection intensities, the electric-field-induced distortion of PO4 and GaO4 tetrahedra in alpha-GaPO4 crystals is evaluated using a model of pseudoatomic displacements introduced recently [Gorfman, Tsirelson & Pietsch (2005). Acta Cryst. A61, 387- 396]. A stronger variation of the P-O bond lengths in the PO4 tetrahedron was found compared to the bonds in the GaO4 tetrahedron. The different distortions of the tetrahedra owing to the electric field were analysed in terms of the valence charge density of alpha-GaPO4 and its topological characteristics. The larger charge of the P pseudoatom compared to the Ga atom was recognized as the main reason for the higher sensitivity of the PO4 tetrahedron to a permanent external electric field Y1 - 2006 UR - http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1600-5724 U6 - https://doi.org/10.1107/S0108767305036111 SN - 0108-7673 ER - TY - JOUR A1 - Tetenoire, Auguste A1 - Ehlert, Christopher A1 - Juaristi, Joseba Iñaki A1 - Saalfrank, Peter A1 - Alducin, Maite T1 - Why ultrafast photoinduced CO desorption dominates over oxidation on Ru(0001) JF - The journal of physical chemistry letters N2 - CO oxidation on Ru(0001) is a long-standing example of a reaction that, being thermally forbidden in ultrahigh vacuum, can be activated by femtosecond laser pulses. In spite of its relevance, the precise dynamics of the photoinduced oxidation process as well as the reasons behind the dominant role of the competing CO photodesorption remain unclear. Here we use ab initio molecular dynamics with electronic friction that account for the highly excited and nonequilibrated system created by the laser to investigate both reactions. Our simulations successfully reproduce the main experimental findings: the existence of photoinduced oxidation and desorption, the large desorption to oxidation branching ratio, and the changes in the O K-edge X-ray absorption spectra attributed to the initial stage of the oxidation process. Now, we are able to monitor in detail the ultrafast CO desorption and CO oxidation occurring in the highly excited system and to disentangle what causes the unexpected inertness to the otherwise energetically favored oxidation. Y1 - 2022 U6 - https://doi.org/10.1021/acs.jpclett.2c02327 SN - 1948-7185 VL - 13 IS - 36 SP - 8516 EP - 8521 PB - American Chemical Society CY - Washington, DC ER - TY - JOUR A1 - Fudickar, Werner A1 - Linker, Torsten T1 - Why triple bonds protect acenes from oxidation and decomposition JF - Journal of the American Chemical Society N2 - An experimental and computational study on the impact of functional groups on the oxidation stability of higher acenes is presented. We synthesized anthracenes, tetracenes, and pentacenes with various substituents at the periphery, identified their photooxygenation products, and measured the kinetics. Furthermore, the products obtained from thermolysis and the kinetics of the thermolysis are investigated. Density functional theory is applied in order to predict reaction energies, frontier molecular orbital interactions, and radical stabilization energies. The combined results allow us to describe the mechanisms of the oxidations and the subsequent thermolysis. We found that the alkynyl group not only enhances the oxidation stability of acenes but also protects the resulting endoperoxides from thermal decomposition. Additionally, such substituents increase the regioselectivity of the photooxygenation of tetracenes and pentacenes. For the first time, we oxidized alkynylpentacenes by using chemically generated singlet oxygen (O-1(2)) without irradiation and identified a 6,13-endoperoxide as the sole regioisomer. The bimolecular rate constant of this oxidation amounts to only 1 X 10(5) s(-1) M-1. This unexpectedly slow reaction is a result of a physical deactivation of O-1(2). In contrast to unsubstituted or aryl-substituted acenes, photooxygenation of alkynyl-substituted acenes proceeds most likely by a concerted mechanism, while the thermolysis is well explained by the formation of radical intermediates. Our results should be important for the future design of oxidation stable acene-based semiconductors. Y1 - 2012 U6 - https://doi.org/10.1021/ja306056x SN - 0002-7863 VL - 134 IS - 36 SP - 15071 EP - 15082 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Behrens, Karsten A1 - Matthes, Philipp R. A1 - Schönfeld, Fabian A1 - Nitsch, Jörn A1 - Steffen, Andreas A1 - Primus, Philipp-Alexander A1 - Kumke, Michael Uwe A1 - Müller-Buschbaum, Klaus A1 - Holdt, Hans-Jürgen T1 - White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+ JF - Journal of materials chemistry : C, Materials for optical and electronic devices N2 - Co-doping of the MOF 3∞[Zn(2-methylimidazolate-4-amide-5-imidate)] (IFP-1 = Imidazolate Framework Potsdam-1) with luminescent Eu3+ and Tb3+ ions presents an approach to utilize the porosity of the MOF for the intercalation of luminescence centers and for tuning of the chromaticity to the emission of white light of the quality of a three color emitter. Organic based fluorescence processes of the MOF backbone as well as metal based luminescence of the dopants are combined to one homogenous single source emitter while retaining the MOF's porosity. The lanthanide ions Eu3+ and Tb3+ were doped in situ into IFP-1 upon formation of the MOF by intercalation into the micropores of the growing framework without a structure directing effect. Furthermore, the color point is temperature sensitive, so that a cold white light with a higher blue content is observed at 77 K and a warmer white light at room temperature (RT) due to the reduction of the organic emission at higher temperatures. The study further illustrates the dependence of the amount of luminescent ions on porosity and sorption properties of the MOF and proves the intercalation of luminescence centers into the pore system by low-temperature site selective photoluminescence spectroscopy, SEM and EDX. It also covers an investigation of the border of homogenous uptake within the MOF pores and the formation of secondary phases of lanthanide formates on the surface of the MOF. Crossing the border from a homogenous co-doping to a two-phase composite system can be beneficially used to adjust the character and warmth of the white light. This study also describes two-color emitters of the formula Ln@IFP-1a–d (Ln: Eu, Tb) by doping with just one lanthanide Eu3+ or Tb3+. Y1 - 2015 U6 - https://doi.org/10.1039/C4TC02919D SN - 2050-7534 SN - 2050-7526 VL - 18 IS - 3 SP - 4623 EP - 4631 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Mondal, Suvendu Sekhar A1 - Behrens, Karsten A1 - Matthes, Philipp R. A1 - Schönfeld, Fabian A1 - Nitsch, Jörn A1 - Steffen, Andreas A1 - Primus, Philipp-Alexander A1 - Kumke, Michael Uwe A1 - Müller-Buschbaum, Klaus A1 - Holdt, Hans-Jürgen T1 - White light emission of IFP-1 by in situ co-doping of the MOF pore system with Eu3+ and Tb3+ JF - Journal of materials chemistry : C, Materials for optical and electronic devices Y1 - 2015 U6 - https://doi.org/10.1039/c4tc02919d SN - 2050-7526 SN - 2050-7534 VL - 3 IS - 18 SP - 4623 EP - 4631 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Meiling, Till T. A1 - Cywinski, Piotr J. A1 - Bald, Ilko T1 - White carbon: Fluorescent carbon nanoparticles with tunable quantum yield in a reproducible green synthesis JF - Scientific reports N2 - In this study, a new reliable, economic, and environmentally-friendly one-step synthesis is established to obtain carbon nanodots (CNDs) with well-defined and reproducible photoluminescence (PL) properties via the microwave-assisted hydrothermal treatment of starch and Tris-acetate-EDTA (TAE) buffer as carbon sources. Three kinds of CNDs are prepared using different sets of above mentioned starting materials. The as-synthesized CNDs: C-CND (starch only), N-CND 1 (starch in TAE) and N-CND 2 (TAE only) exhibit highly homogenous PL and are ready to use without need for further purification. The CNDs are stable over a long period of time (> 1 year) either in solution or as freeze-dried powder. Depending on starting material, CNDs with PL quantum yield (PLQY) ranging from less than 1% up to 28% are obtained. The influence of the precursor concentration, reaction time and type of additives on the optical properties (UV-Vis absorption, PL emission spectrum and PLQY) is carefully investigated, providing insight into the chemical processes that occur during CND formation. Remarkably, upon freeze-drying the initially brown CND-solution turns into a non-fluorescent white/slightly brown powder which recovers PL in aqueous solution and can potentially be applied as fluorescent marker in bio-imaging, as a reduction agent or as a photocatalyst. Y1 - 2016 U6 - https://doi.org/10.1038/srep28557 SN - 2045-2322 VL - 6 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Meiling, Till Thomas A1 - Cywiński, Piotr J. A1 - Bald, Ilko T1 - White carbon: Fluorescent carbon nanoparticles with tunable quantum yield in a reproducible green synthesis JF - Scientific reports N2 - In this study, a new reliable, economic, and environmentally-friendly one-step synthesis is established to obtain carbon nanodots (CNDs) with well-defined and reproducible photoluminescence (PL) properties via the microwave-assisted hydrothermal treatment of starch and Tris-acetate-EDTA (TAE) buffer as carbon sources. Three kinds of CNDs are prepared using different sets of above mentioned starting materials. The as-synthesized CNDs: C-CND (starch only), N-CND 1 (starch in TAE) and N-CND 2 (TAE only) exhibit highly homogenous PL and are ready to use without need for further purification. The CNDs are stable over a long period of time (>1 year) either in solution or as freeze-dried powder. Depending on starting material, CNDs with PL quantum yield (PLQY) ranging from less than 1% up to 28% are obtained. The influence of the precursor concentration, reaction time and type of additives on the optical properties (UV-Vis absorption, PL emission spectrum and PLQY) is carefully investigated, providing insight into the chemical processes that occur during CND formation. Remarkably, upon freeze-drying the initially brown CND-solution turns into a non-fluorescent white/slightly brown powder which recovers PL in aqueous solution and can potentially be applied as fluorescent marker in bio-imaging, as a reduction agent or as a photocatalyst. KW - Fluorescence spectroscopy KW - Nanoparticles KW - Synthesis and processing Y1 - 2016 U6 - https://doi.org/10.1038/srep28557 VL - 6 PB - Nature Publishing Group CY - London ER - TY - JOUR A1 - Khadem, S. M. J. A1 - Hille, Carsten A1 - Löhmannsröben, Hans-Gerd A1 - Sokolov, Igor M. T1 - What information is contained in the fluorescence correlation spectroscopy curves, and where JF - Physical review : E, Statistical, nonlinear and soft matter physics Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevE.94.022407 SN - 2470-0045 SN - 2470-0053 VL - 94 PB - American Physical Society CY - College Park ER -