TY - JOUR A1 - Trautwein, Matthias A1 - Fredriksson, Kai A1 - Möller, Heiko Michael A1 - Exner, Thomas E. T1 - Automated assignment of NMR chemical shifts based on a known structure and 4D spectra JF - Journal of biomolecular NMR N2 - Apart from their central role during 3D structure determination of proteins the backbone chemical shift assignment is the basis for a number of applications, like chemical shift perturbation mapping and studies on the dynamics of proteins. This assignment is not a trivial task even if a 3D protein structure is known and needs almost as much effort as the assignment for structure prediction if performed manually. We present here a new algorithm based solely on 4D [H-1, N-15]-HSQC-NOESY-[H-1, N-15]-HSQC spectra which is able to assign a large percentage of chemical shifts (73-82 %) unambiguously, demonstrated with proteins up to a size of 250 residues. For the remaining residues, a small number of possible assignments is filtered out. This is done by comparing distances in the 3D structure to restraints obtained from the peak volumes in the 4D spectrum. Using dead-end elimination, assignments are removed in which at least one of the restraints is violated. Including additional information from chemical shift predictions, a complete unambiguous assignment was obtained for Ubiquitin and 95 % of the residues were correctly assigned in the 251 residue-long N-terminal domain of enzyme I. The program including source code is available at https://github.com/thomasexner/4Dassign. KW - Chemical shift assignment KW - Protein KW - 3D structure KW - 4D NOESY Y1 - 2016 U6 - https://doi.org/10.1007/s10858-016-0050-0 SN - 0925-2738 SN - 1573-5001 VL - 65 SP - 217 EP - 236 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Maier, Stefan K. A1 - Poluektov, Georgiy A1 - Jester, Stefan-S. A1 - Möller, Heiko Michael A1 - Hoeger, Sigurd T1 - Fast Oxidative Cyclooligomerization towards Low- and High-Symmetry Thiophene Macrocycles JF - Chemistry - a European journal N2 - Macrocycles with quaterthiophene subunits were obtained by cyclooligomerization by direct oxidative coupling of unsubstituted dithiophene moieties. The rings were closed with high selectivity by an α,β′-connection of the thiophenes as proven by NMR spectroscopy. The reaction of the precursor with terthiophene moieties yielded the symmetric α,α′-linked macrocycle in low yield together with various differently connected isomers. Blocking of the β-position of the half-rings yielded selectively the α,α′-linked macrocycle. Selected cyclothiophenes were investigated by scanning tunneling microscopy, which displayed the formation of highly ordered 2D crystalline monolayers. KW - cyclooligomers KW - scanning tunneling microscopy KW - self-assembled monolayers KW - shape-persistent macrocycles KW - thiophenes Y1 - 2016 U6 - https://doi.org/10.1002/chem.201503211 SN - 0947-6539 SN - 1521-3765 VL - 22 SP - 1379 EP - 1384 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Prestel, Andreas A1 - Möller, Heiko Michael T1 - Spatio-temporal control of cellular uptake achieved by photoswitchable cell-penetrating peptides JF - Chemical communications N2 - The selective uptake of compounds into specific cells of interest is a major objective in cell biology and drug delivery. By incorporation of a novel, thermostable azobenzene moiety we generated peptides that can be switched optically between an inactive state and an active, cell-penetrating state with excellent spatio-temporal control. Y1 - 2016 U6 - https://doi.org/10.1039/c5cc06848g SN - 1359-7345 SN - 1364-548X VL - 52 SP - 701 EP - 704 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Holert, Johannes A1 - Yücel, Onur A1 - Jagmann, Nina A1 - Prestel, Andreas A1 - Möller, Heiko Michael A1 - Philipp, Bodo T1 - Identification of bypass reactions leading to the formation of one central steroid degradation intermediate in metabolism of different bile salts in Pseudomonas sp strain Chol1 JF - Environmental microbiology Y1 - 2016 U6 - https://doi.org/10.1111/1462-2920.13192 SN - 1462-2912 SN - 1462-2920 VL - 18 SP - 3373 EP - 3389 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Vorburger, Thomas A1 - Nedielkov, Ruslan A1 - Brosig, Alexander A1 - Bok, Eva A1 - Schunke, Emina A1 - Steffen, Wojtek A1 - Mayer, Sonja A1 - Goetz, Friedrich A1 - Möller, Heiko Michael A1 - Steuber, Julia T1 - Role of the Na+-translocating NADH:quinone oxidoreductase in voltage generation and Na+ extrusion in Vibrio cholerae JF - Biochimica et biophysica acta : Bioenergetics N2 - For Vibrio cholerae, the coordinated import and export of Na+ is crucial for adaptation to habitats with different osmolarities. We investigated the Na+-extruding branch of the sodium cycle in this human pathogen by in vivo Na-23-NMR spectroscopy. The Na+ extrusion activity of cells was monitored after adding glucose which stimulated respiration via the Na+-translocating NADH:quinone oxidoreductase (Na+-NQR). In a V. cholerae deletion mutant devoid of the Na+-NQR encoding genes (nqrA-F), rates of respiratory Na+ extrusion were decreased by a factor of four, but the cytoplasmic Na+ concentration was essentially unchanged. Furthermore, the mutant was impaired in formation of transmembrane voltage (Delta psi, inside negative) and did not grow under hypoosmotic conditions at pH 8.2 or above. This growth defect could be complemented by transformation with the plasmid encoded nqr operon. In an alkaline environment, Na+/H+ antiporters acidify the cytoplasm at the expense of the transmembrane voltage. It is proposed that, at alkaline pH and limiting Na+ concentrations, the Na+-NQR is crucial for generation of a transmembrane voltage to drive the import of H+ by electrogenic Na+/H+ antiporters. Our study provides the basis to understand the role of the Na+-NQR in pathogenicity of V. cholerae and other pathogens relying on this primary Na+ pump for respiration. (C) 2015 Elsevier B.V. All rights reserved. KW - Nuclear magnetic resonance (NMR) KW - Sodium transport KW - Vibrio cholerae KW - Respiration KW - Na+ homeostasis KW - Hypoosmotic stress Y1 - 2016 U6 - https://doi.org/10.1016/j.bbabio.2015.12.010 SN - 0005-2728 SN - 0006-3002 VL - 1857 SP - 473 EP - 482 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Krüger, Tobias A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Linker, Torsten T1 - Simple Synthesis of gamma-Spirolactams by Birch Reduction of Benzoic Acids JF - European journal of organic chemistry N2 - A convenient synthesis of gamma-spirolactams in only two steps was developed. Birch reduction of benzoic acids and immediate alkylation with chloroacetonitrile afforded cyclohexadienes in high yields. The products could be isolated by crystallization on a large scale in analytically pure form. Subsequent hydrogenation with platinum(IV) oxide as the catalyst reduced the nitrile functionality and the double bonds in the same step with excellent stereoselectivity. The relative configurations were determined unequivocally by X-ray analyses. Direct cyclization of the intermediary formed amino acids afforded the desired gamma-spirolactams in excellent overall yields. The procedure is characterized by few steps, cheap reagents, and can be performed on a large scale, interesting for industrial processes. KW - Diastereoselectivity KW - Hydrogenation KW - Lactams KW - Reduction KW - Synthetic methods Y1 - 2016 U6 - https://doi.org/10.1002/ejoc.201601650 SN - 1434-193X SN - 1099-0690 IS - 6 SP - 1074 EP - 1077 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Pacholski, Claudia A1 - Agarwal, Vivechana A1 - Balderas-Valadez, Ruth Fabiola T1 - Fabrication of porous silicon-based optical sensors using metal-assisted chemical etching N2 - Optical biosensors based on porous silicon were fabricated by metal assisted chemical etching. Thereby double layered porous silicon structures were obtained consisting of porous pillars with large pores on top of a porous silicon layer with smaller pores. These structures showed a similar sensing performance in comparison to electrochemically produced porous silicon interferometric sensors. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 316 KW - fourier-transform spectroscopy KW - nanostructures KW - nanowires Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-394426 SP - 21430 EP - 21434 ER - TY - THES A1 - Audörsch, Stephan T1 - Die Synthese von (2Z,4E)-Diencarbonsäureestern und ihre Anwendung in der Totalsynthese von Polyacetylenen T1 - Synthesis of (2Z,4E)-dienoic acid ester and their application in the total synthesis of natural occurring polyacetylenes N2 - Z,E-Diene sind ein häufig auftretendes Strukturmerkmal in Naturstoffen. Aus diesem Grund ist die einfache Darstellung dieser Struktureinheit von großen Interesse in der organischen Chemie. Das erste Ziel der vorliegenden Arbeit war daher die Weiterentwicklung der Ringschlussmetathese-/ baseninduzierten Ringöffnungs-/ Veresterungssequenz (RBRV-Sequenz) zur Synthese von (2Z,4E)-Diencarbonsäureethylestern ausgehend von Butenoaten. Dazu wurde zunächst die RBRV-Sequenz optimiert. Diese aus drei Schritten bestehende Sequenz konnte in einem Eintopf-Verfahren angewendet werden. Die Ringschlussmetathese gelang mit einer Katalysatorbeladung von 1 mol% des GRUBBS-Katalysators der zweiten Generation in Dichlormethan. Für die baseninduzierte Ringöffnung des β,γ-ungesättigten δ Valerolactons wurde NaHMDS verwendet. Die Alkylierung der Carboxylatspezies gelang mit dem MEERWEIN-Reagenz. Die Anwendbarkeit der Sequenz wurde für verschiedene Substrate demonstriert. Die Erweiterung der Methode auf α-substituierte Butenoate unterlag starken Einschränkungen. So konnte der Zugang für α Hydroxyderivate realisiert werden. Bei der Anwendung der RBRV-Sequenz auf die α-substituierten Butenoate wurde festgestellt, dass diese sich nur in moderaten Ausbeuten umsetzen ließen und zudem nicht selektiv zu den (2E,4E)-konfigurierten α-substituierten-Dienestern reagierten. Der Einsatz von Eninen unter den Standardbedingungen der RBRV-Sequenz gelang nicht. Erst nach Modifizierung der Sequenz (höhere Katalysatorbeladung, Wechsel des Lösungsmittels) konnten die [3]Dendralen-Produkte in geringen Ausbeuten erhalten werden. Im zweiten Teil der Arbeit wurde der Einsatz von (2Z,4E)-Diencarbonsäureethylestern in der Totalsynthese von Naturstoffen untersucht. Dazu wurden zunächst die Transformationsmöglichkeiten der Ester geprüft. Es konnte gezeigt werden, dass sich (2Z,4E)-Diencarbonsäureethylester insbesondere zur Synthese von (2Z,4E)-Aldehyden sowie zum Aufbau der (3Z,5E)-Dien-1-in-Struktur eignen. Anhand dieser Ergebnisse wurde im Anschluss die RBRV-Sequenz in der Totalsynthese eingesetzt. Dazu wurde zunächst der (2Z,4E)-Dienester Microsphaerodiolin in seiner ersten Totalsynthese auf drei verschiedene Routen hergestellt. Im Anschluss wurden sechs verschiedene Polyacetylene mit einer (3Z,5E)-Dien-1-in-Einheit hergestellt. Schlüsselschritte in ihrer Synthese waren immer die RBRV-Sequenz zum Aufbau der Z,E-Dien-Einheit, die Transformation des Esters in ein terminales Alkin sowie die CADIOT-CHODKIEWICZ-Kupplung zum Aufbau unsymmetrischer Polyine. Alle sechs Polyacetylene wurden zum ersten Mal in einer Totalsynthese synthetisiert. Drei Polyacetylene wurden ausgehend von (S)-Butantriol enantiomerenrein dargestellt. Anhand ihrer Drehwerte konnte eine Revision der von YAO und Mitarbeitern vorgenommen Zuordnung der Absolutkonfiguration der Naturstoffe vorgenommen werden. N2 - Z,E-Dienes are a common motif in natural products. Therefore their simple preparation is of high interest. The first part of this work focuses on the improvement of the one-pot sequence “RBRV” consisting of three steps: ring closing metathesis, base induced ring opening and esterification of butenoates. This method yields (2Z,4E) dienoic acid esters. As optimized conditions were found the use of Grubbs catalysts 2nd Generation in dichloromethane, NaHMDS as base and Meerwein’s reagent as alkylating agent. The extension of this method on α-substituted butenoates was subject to many restrictions. The synthesis of precursors was realized for α-hydroxy derivates only. Application of these substrates in the RBRV sequence gave the desired products in moderate yield and diminished selectivity. The use of enines was demonstrated as well. For these substrates changes of the conditions were necessary. The products, [3]dendralenes, were obtained in low yield and excellent selectivity. The second part of this thesis focuses on the application of the RBRV-sequence in the total synthesis of natural products with a Z,E-diene unit. For this purpose it was demonstrated how the ester function can be transformed. As result it was shown that especially Z,E-diene-alkynes can be easily synthesized from Z,E-diene esters. Based on these results the RBRV was used in the synthesis of some natural products. These include Microsphaerodiolin, Atractylodemayne A, C and F as well as three other, unnamed, polyacetylenes. All of them have been synthesized for the first time. Three of them were synthesized in enatioselective manner utilizing enantiopure 1,2,4-butane triole as starting material. KW - Polyacetylene KW - Totalsynthese KW - 2Z,4E-Diencarbonsäureester KW - organische Chemie KW - polyacetylenes KW - total synthesis KW - organic chemistry Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-92366 ER - TY - THES A1 - Pape, Simon T1 - Entwicklung und Evaluierung von Methoden zur Synthese neuartiger Additive für die außenstromlose Nickel-Phosphor-Abscheidung Y1 - 2016 ER - TY - THES A1 - Won, Jooyoung T1 - Dynamic and equilibrium adsorption behaviour of ß-lactoglobulin at the solution/tetradecane interface: Effect of solution concentration, pH and ionic strength T1 - Dynamik und Gleichgewicht der Adsorption von ß-Lactoglobulin an der Grenzfläche Lösung / Tetradecan (W/TD) N2 - Proteins are amphiphilic and adsorb at liquid interfaces. Therefore, they can be efficient stabilizers of foams and emulsions. β-lactoglobulin (BLG) is one of the most widely studied proteins due to its major industrial applications, in particular in food technology. In the present work, the influence of different bulk concentration, solution pH and ionic strength on the dynamic and equilibrium pressures of BLG adsorbed layers at the solution/tetradecane (W/TD) interface has been investigated. Dynamic interfacial pressure (Π) and interfacial dilational elastic modulus (E’) of BLG solutions for various concentrations at three different pH values of 3, 5 and 7 at a fixed ionic strength of 10 mM and for a selected fixed concentration at three different ionic strengths of 1 mM, 10 mM and 100 mM are measured by Profile Analysis Tensiometer PAT-1 (SINTERFACE Technologies, Germany). A quantitative data analysis requires additional consideration of depletion due to BLG adsorption at the interface at low protein bulk concentrations. This fact makes experiments more efficient when oil drops are studied in the aqueous protein solutions rather than solution drops formed in oil. On the basis of obtained experimental data, concentration dependencies and the effect of solution pH on the protein surface activity was qualitatively analysed. In the presence of 10 mM buffer, we observed that generally the adsorbed amount is increasing with increasing BLG bulk concentration for all three pH values. The adsorption kinetics at pH 5 result in the highest Π values at any time of adsorption while it exhibits a less active behaviour at pH 3. Since the experimental data have not been in a good agreement with the classical diffusion controlled model due to the conformational changes which occur when the protein molecules get in contact with the hydrophobic oil phase in order to adapt to the interfacial environment, a new theoretical model is proposed here. The adsorption kinetics data were analysed with the newly proposed model, which is the classical diffusion model but modified by assuming an additional change in the surface activity of BLG molecules when adsorbing at the interface. This effect can be expressed through the adsorption activity constant in the corresponding equation of state. The dilational visco-elasticity of the BLG adsorbed interfacial layers is determined from measured dynamic interfacial tensions during sinusoidal drop area variations. The interfacial tension responses to these harmonic drop oscillations are interpreted with the same thermodynamic model which is used for the corresponding adsorption isotherm. At a selected BLG concentration of 2×10-6 mol/l, the influence of the ionic strength using different buffer concentration of 1, 10 and 100 mM on the interfacial pressure was studied. It is affected weakly at pH 5, whereas it has a strong impact by increasing buffer concentration at pH 3 and 7. In conclusion, the structure formation of BLG adsorbed layer in the early stage of adsorption at the W/TD interface is similar to those of the solution/air (W/A) surface. However, the equation of state at the W/TD interface provides an adsorption activity constant which is almost two orders of magnitude higher than that for the solution/air surface. At the end of this work, a new experimental tool called Drop and Bubble Micro Manipulator DBMM (SINTERFACE Technologies, Germany) has been introduced to study the stability of protein covered bubbles against coalescence. Among the available protocols the lifetime between the moment of contact and coalescence of two contacting bubble is determined for different BLG concentrations. The adsorbed amount of BLG is determined as a function of time and concentration and correlates with the observed coalescence behaviour of the contacting bubbles. N2 - Die vorliegende Arbeit ist ein Beitrag zum Verständnis des Überganges von der qualitativen zur quantitativen Beschreibung der Adsorption von Proteinen an der Wasser/Öl- Grenzfläche. Dabei wird die Adsorption des Molkeproteins ß-Lactoglobulin (BLG) an der Wasser/Tetradekan (W/TD) Grenzfläche untersucht. Die Proteinadsorption an Grenzflächen zwischen zwei nicht mischbaren Flüssigkeiten ist ein Zeitprozess. Die Tropfenprofil-Analysen-Tensiometrie (PAT) hat sich als optimale Methode erwiesen, um den Prozess der Bildung von Proteinadsorptionsschichten an Flüssig-/flüssig-Grenzflächen quantitativ zu untersuchen. Die gemessenen dynamischen Grenzflächenspannungen können genutzt werden, um die adsorbierte Menge von Protein an Grenzflächen zu bestimmen. Zusätzlich erlaubt die Methode, durch periodische Tropfenoszillationen, die Messung der Dilatations-Viskoelastizität. Die experimentellen Ergebnisse zeigen deutlich, dass die Adsorption von Proteinen mit der Konzentration ansteigt. Der Adsorptionsprozess von Proteinen ist ähnlich dem von Tensiden, allerdings wird seine Beschreibung wesentlich komplizierter, durch die zusätzliche Möglichkeit der Konformationsänderungen der Proteinmoleküle an der Grenzfläche. Ein kürzlich im Rahmen dieser Dissertation entwickeltes Modell zur Adsorptionskinetik von Proteinen wurde genutzt, um experimentelle Daten für BLG zu interpretieren. Dieses kinetische Modell erlaubt es, den Mechanismus der Proteinadsorption an der Wasser/Öl-Grenzfläche zu beschreiben, was durch ältere Modelle bisher nicht möglich war. Im neu entwickelten Modell wurde die klassische Diffusionstheorie so modifiziert, dass eine Änderung der Adsorptionsaktivität der adsorbierenden Proteinmoleküle berücksichtigt wird. Die Änderung der Adsorptionsaktivität geschieht durch den Kontakt adsorbierter BLG-Moleküle an der Wasser/Öl-Grenzfläche. Es wird nach diesem neuen Modell angenommen, dass die Adsorptionsaktivität eine Funktion der Adsorptionszeit ist. Die ansteigende Adsorptionaktivität ist erforderlich, um den Adsorptionsprozess von BLG über den gesamten Zeitbereich quantitativ zu beschrieben. Mit diesem neuen Modell wurde es möglich, die experimentellen Daten zur Adsorptionskinetik sowie zur Dilatationsrheologie von Adsorptionsschichten bei unterschiedlichen BLG-Konzentrationen, pH-Werten und Ionenstärken an der Grenzfläche Lösung/Tetradekan quantitativ zu beschreiben. Die Ergebnisse dienen als Ausgangspunkt für weitere Entwicklungen zur Verbesserung des Verständnisses der Stabilität von Schäumen und Emulsionen, die durch die Dynamik der Adsorption von Molekülen wie BLG signifikant beeinflusst wird. KW - beta-lactoglobulin KW - water/tetradecane interface KW - drop profile analysis tensiometry KW - dynamic interfacial tensions KW - protein adsorption KW - pH effect KW - ionic strength effect KW - protein stabilized foams KW - drop and bubble coalescence KW - interfacial dynamics KW - capillary pressure tensiometry KW - drop-drop interaction KW - bubble-bubble interaction KW - ß-Lactoglobulin KW - Flüssig-/flüssig-Grenzflächen KW - Wasser/Öl-Grenzfläche KW - Grenzfläche Lösung/Tetradecan KW - Dynamik der Adsorption KW - Gleichgewicht der Adsorption KW - Proteinadsorption KW - Tropfenprofil-Analysen-Tensiometrie KW - Tropfenoszillationen KW - Dilatations-Viskoelastizität KW - klassische Diffusionstheorie KW - Konformationsänderungen KW - Adsorptionsaktivität KW - Wirkung des pH-Werten KW - Wirkung des Ionenstärken KW - Stabilität von Schäumen KW - Stabilität von Emulsionen Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-99167 ER - TY - JOUR A1 - Zabel, André A1 - Winter, Alette A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strauch, Peter T1 - Tetrabromidocuprates(II)-Synthesis, Structure and EPR JF - International journal of molecular sciences N2 - Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and gK) of the tensors could be determined and information on the structural changes in the [CuBr4]2- anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. KW - tetrabromidocuprate(II) KW - X-ray structure KW - electron paramagnetic resonance KW - copper(II) Y1 - 2016 U6 - https://doi.org/10.3390/ijms17040596 VL - 17 IS - 4 PB - MDPI CY - Basel ER - TY - GEN A1 - Zabel, André A1 - Winter, Alette A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strauch, Peter T1 - Tetrabromidocuprates(II)-Synthesis, Structure and EPR N2 - Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and gK) of the tensors could be determined and information on the structural changes in the [CuBr4]2- anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 226 KW - tetrabromidocuprate(II) KW - X-ray structure KW - electron paramagnetic resonance KW - copper(II) Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-91470 ER - TY - THES A1 - Couturier, Jean-Philippe T1 - New inverse opal hydrogels as platform for detecting macromolecules T1 - Neue inverse Opal-Hydrogele als Plattform für die Detektion von Makromolekülen N2 - In this thesis, a route to temperature-, pH-, solvent-, 1,2-diol-, and protein-responsive sensors made of biocompatible and low-fouling materials is established. These sensor devices are based on the sensitivemodulation of the visual band gap of a photonic crystal (PhC), which is induced by the selective binding of analytes, triggering a volume phase transition. The PhCs introduced by this work show a high sensitivity not only for small biomolecules, but also for large analytes, such as glycopolymers or proteins. This enables the PhC to act as a sensor that detects analytes without the need of complex equipment. Due to their periodical dielectric structure, PhCs prevent the propagation of specific wavelengths. A change of the periodicity parameters is thus indicated by a change in the reflected wavelengths. In the case explored, the PhC sensors are implemented as periodically structured responsive hydrogels in formof an inverse opal. The stimuli-sensitive inverse opal hydrogels (IOHs) were prepared using a sacrificial opal template of monodispersed silica particles. First, monodisperse silica particles were assembled with a hexagonally packed structure via vertical deposition onto glass slides. The obtained silica crystals, also named colloidal crystals (CCs), exhibit structural color. Subsequently, the CCs templates were embedded in polymer matrix with low-fouling properties. The polymer matrices were composed of oligo(ethylene glycol) methacrylate derivatives (OEGMAs) that render the hydrogels thermoresponsive. Finally, the silica particles were etched, to produce highly porous hydrogel replicas of the CC. Importantly, the inner structure and thus the ability for light diffraction of the IOHs formed was maintained. The IOH membrane was shown to have interconnected pores with a diameter as well as interconnections between the pores of several hundred nanometers. This enables not only the detection of small analytes, but also, the detection of even large analytes that can diffuse into the nanostructured IOH membrane. Various recognition unit – analyte model systems, such as benzoboroxole – 1,2-diols, biotin – avidin and mannose – concanavalin A, were studied by incorporating functional comonomers of benzoboroxole, biotin and mannose into the copolymers. The incorporated recognition units specifically bind to certain low and highmolar mass biomolecules, namely to certain saccharides, catechols, glycopolymers or proteins. Their specific binding strongly changes the overall hydrophilicity, thus modulating the swelling of the IOH matrices, and in consequence, drastically changes their internal periodicity. This swelling is amplified by the thermoresponsive properties of the polymer matrix. The shift of the interference band gap due to the specific molecular recognition is easily visible by the naked eye (up to 150 nm shifts). Moreover, preliminary trial were attempted to detect even larger entities. Therefore anti-bodies were immobilized on hydrogel platforms via polymer-analogous esterification. These platforms incorporate comonomers made of tri(ethylene glycol) methacrylate end-functionalized with a carboxylic acid. In these model systems, the bacteria analytes are too big to penetrate into the IOH membranes, but can only interact with their surfaces. The selected model bacteria, as Escherichia coli, show a specific affinity to anti-body-functionalized hydrogels. Surprisingly in the case functionalized IOHs, this study produced weak color shifts, possibly opening a path to detect directly living organism, which will need further investigations. N2 - Periodisch strukturierte, funktionelle responsive Hydrogele wurden in Form von inversen Opalen (IOH) aufgebaut und als Basiselement für Temperatur-, pH-, lösungsmittel-, 1,2-diol- oder protein-sensitive Sensorsysteme entwickelt. Dazu wurden aus biokompatiblen Bausteinen funktionelle photonische Kristalle aufgebaut, deren optische Bandlücke durch selektive Bindung eines Analyten moduliert wird, indem dieser einen Volumen-Phasenübergang induziert.Mittels solcher responsiver photonische Kristalle ist es möglich, Analyte ohne aufwendige Geräte durch Farbänderung einfach zu detektieren. Die entwickelten Systeme zeigen nicht nur eine hohe Empfindlichkeit gegenüber kleinen Biomolekülen, sondern auch gegenüber größeren Analyten wie z.B. Glycopolymeren und Proteinen, was bisher nicht bekannt war. Die stimuli-sensitiven inversen Opal Hydrogele (IOHs) wurden in mehreren Stufen hergestellt. Als erstes wurden dafür kolloidale Kristalle mit hexagonal gepackten Strukturen aus monodispersen SiO2-Partikeln auf Glasträgern auf ebaut (“Opal”). Die Opale mit charakteristischen Strukturfarben wurden anschließend in eine polymere Hydrogelmatrix eingebettet. Diese wurde aus Oligo(ethylenglycol)methacrylaten (OEGMAs) hergestellt, so dass die Hydrogele sowohl thermosensitives als auch “lowfouling” Verhalten zeigen. Im letzten Schritt wurden die SiO2-Partikel entfernt und so eine hochporöse Hydrogel-Replika der Opale erhalten unter Erhalt deren innerer Struktur und Strukturfarbe. Die miteinander verbunden Poren der IOHMembran besitzen einen Durchmesser von einigen hundert Nanometern. Dies ermöglichte nicht nur die Detektion von kleinen Analyten, sondern auch die Detektion von deutlich größeren, makromolekularen Analyten, die ebenfalls in die Nanostrukturen der IOH Membran diffundieren können. Modellsysteme bestanden immer aus einer Erkennungsgruppe und einem Analyten, beispielsweise aus Benzoboroxol – 1,2-Diol, Biotin – Avidin und Mannose – Lectin (Concanavalin A). Für dieseModellsysteme wurden OEGMAs mitMonomeren copolymerisiert, die mit Benzoboroxol, Biotin bzw.Mannose funktionalisiert waren. Die so im Polymer eingebauten Erkennungsgruppen binden spezifisch an bestimmte Biomoleküle unterschiedlicherMolmassen, wie z.B. niedermolekulare Saccharide oder Catechin, als auch hochmolekulare Glycopolymere oder Proteine. Der spezifische Bindungsvorgang moduliert die Gesamthydrophilie, so dass sich der Quellgrad der IOH-Matrix ändert. Dies wiederrumverändert die innere Periodizität und damit die Strukturfarbe. Dabei wird der Quelleffekt durch die Thermosensitivität der Hydrogele massiv verstärkt. Eine spezifischeMolekülanbindung lässt sich so optisch, z.T. sogar mit dem Auge, erkennen aufgrund der deutlichen Verschiebung der Strukturfarbe um bis zu 150 nm. Des Weiteren wurden auch erste Versuche zur Detektion von noch größeren Analyten unternommen. Dafür wurden Antiköper durch nachträgliche Modifizierung der Polymerseitenketten auf den Hydrogeloberflächen immobilisiert. Mit diesem Modellsystem konnten unterschiedliche Bakterienarten durch Antikörper spezifisch gebunden werden. Die verwendeten Bakterienarten sind zwar zu groß, um in die Membran des IOH Systems einzudringen, können jedoch mit der IOH-Oberfläche wechselwirken. Insbesondere dasModellsystem mit Escherichia coli zeigte eine starke, spezifische Affinität zu dem Antikörper-funktionalisierten IOH. Überraschenderweise zeigte sich bei den Versuchen in Gegenwart des Analyten eine kleine Farbänderung der funktionalisierten IOH. Damit eröffnet sich u.U. dieMöglichkeit, mit solchen responsiven photonischen Kristallen auch lebende Organismen spezifisch und einfach zu detektieren, was in weiterführenden Arbeiten zu klären sein wird. KW - inverse opal KW - hydrogel KW - responsive polymer KW - inverse Opale KW - Hydrogel KW - schaltbare Polymere Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-98412 ER - TY - THES A1 - Oliveira, Joana Santos Lapa T1 - Role of different ceramides on the nanostructure of Stratum Corneum models and the influence of selected penetration enhancers Y1 - 2016 ER - TY - THES A1 - Wolf, Felix T1 - Neuartige Olefine und Aryldiazoniumtetrafluoroborate für die MATSUDA-HECK-Reaktion Y1 - 2016 ER - TY - THES A1 - Hildebrand, Viet T1 - Twofold switchable block copolymers based on new polyzwitterions T1 - Neue Polyzwitterionbasierte Blockcopolymere mit „Schizophrenem Verhalten“ N2 - In complement to the well-established zwitterionic monomers 3-((2-(methacryloyloxy)ethyl)dimethylammonio)propane-1-sulfonate (“SPE”) and 3-((3-methacrylamidopropyl)dimethylammonio)propane-1-sulfonate (“SPP”), the closely related sulfobetaine monomers were synthesized and polymerized by reversible addition-fragmentation chain transfer (RAFT) polymerization, using a fluorophore labeled RAFT agent. The polyzwitterions of systematically varied molar mass were characterized with respect to their solubility in water, deuterated water, and aqueous salt solutions. These poly(sulfobetaine)s show thermoresponsive behavior in water, exhibiting upper critical solution temperatures (UCST). Phase transition temperatures depend notably on the molar mass and polymer concentration, and are much higher in D2O than in H2O. Also, the phase transition temperatures are effectively modulated by the addition of salts. The individual effects can be in parts correlated to the Hofmeister series for the anions studied. Still, they depend in a complex way on the concentration and the nature of the added electrolytes, on the one hand, and on the detailed structure of the zwitterionic side chain, on the other hand. For the polymers with the same zwitterionic side chain, it is found that methacrylamide-based poly(sulfobetaine)s exhibit higher UCST-type transition temperatures than their methacrylate analogs. The extension of the distance between polymerizable unit and zwitterionic groups from 2 to 3 methylene units decreases the UCST-type transition temperatures. Poly(sulfobetaine)s derived from aliphatic esters show higher UCST-type transition temperatures than their analogs featuring cyclic ammonium cations. The UCST-type transition temperatures increase markedly with spacer length separating the cationic and anionic moieties from 3 to 4 methylene units. Thus, apparently small variations of their chemical structure strongly affect the phase behavior of the polyzwitterions in specific aqueous environments. Water-soluble block copolymers were prepared from the zwitterionic monomers and the non-ionic monomer N-isopropylmethacrylamide (“NIPMAM”) by the RAFT polymerization. Such block copolymers with two hydrophilic blocks exhibit twofold thermoresponsive behavior in water. The poly(sulfobetaine) block shows an UCST, whereas the poly(NIPMAM) block exhibits a lower critical solution temperature (LCST). This constellation induces a structure inversion of the solvophobic aggregate, called “schizophrenic micelle”. Depending on the relative positions of the two different phase transitions, the block copolymer passes through a molecularly dissolved or an insoluble intermediate regime, which can be modulated by the polymer concentration or by the addition of salt. Whereas, at low temperature, the poly(sulfobetaine) block forms polar aggregates that are kept in solution by the poly(NIPMAM) block, at high temperature, the poly(NIPMAM) block forms hydrophobic aggregates that are kept in solution by the poly(sulfobetaine) block. Thus, aggregates can be prepared in water, which switch reversibly their “inside” to the “outside”, and vice versa. N2 - Diese Arbeit befasst sich mit der Synthese und Charakterisierung von doppelt thermisch-responsiven Blockcopolymeren mit einem polaren nicht-ionischen Block (der einen LCST-Übergang in wässriger Lösung induziert) und einem zwitterionischen Block (der einen UCST-Übergang aufweisen soll), der durch Salzzusatz über einen weiten Temperaturbereich modulierbar ist. Dafür wurden geeignete zwitterionische Polymer¬blöcke identifiziert und hergestellt, die ein derartiges Löslichkeitsprofil aufweisen. Da bislang nur relativ wenige Poly-sulfobetaine beschrieben sind und entsprechend das wässrige Phasenverhalten nur für einzelne ausgewählte Polymere bekannt ist, wurde ein Grundverständnis von chemischer Struktur und Phasen¬übergangs¬verhalten durch eine systematische Variation des Substitutionsmusters angestrebt. Die als geeignet erkannten Sulfobetain-Monomere wurden mit dem nicht-ionischen Monomer N-Isopropyl-methacrylamid („NIPMAM“) zu Blockcopolymeren von unterschiedlicher Größe und Blocklängen zusammengefügt. Die neuen Blockcopolymere wurden anschließend bezüglich der Lage der Phasenübergänge mit Trübheitsmessungen untersucht. Es wurden 2 Serien neuer zwitterionischer Monomere synthetisiert, deren Struktur den sehr gut untersuchten 3-((2-(methacryloyloxy)ethyl)dimethylammonio)propane-1-sulfonate („SPE“) und 3-((3-methacrylamidopropyl)dimethylammonio)propane-1-sulfonate („SPP“) ähnlich ist. Aus den Monomeren wurden fluoreszenz-markierte Homopolymere mit unterschiedlichen Molmassen mittels der Reversiblen Additions-Fragmentierungs Kettenübertragungs (RAFT) – Polymerisation unter Verwendung eines geeigneten RAFT Reagenzes synthetisiert. Die Poly¬sulfobetaine wurden bezüglich ihrer Löslichkeit in Wasser, in deuteriertem Wasser und in Salzlösungen untersucht. Ihr wässriges Phasenverhalten mit einem UCST-Übergang ist stark abhängig von ihrer Molmasse und von der Polymerkonzentration der untersuchten Lösung. Auffällig ist, dass die Phasenübergangstemperatur in D2O deutlich höher liegt als in H2O. Des Weiteren konnten die Löslichkeit und Phasen-übergangstemperatur durch Salzzusatz effektiv moduliert werden. Prinzipiell stellte sich bei den untersuchten Anionen heraus, dass das Einsalzen bzw. das Aussalzen der empirischen Hofmeister Serie folgt. Dabei hängen die individuellen Effekte sehr stark von der Konzentration und von der Art des Salzes, aber auch in nicht-trivialer Weise von der detaillierten zwitterionischen Struktur stark ab. Durch die systematische Variation der Monomerstruktur wurden interessante Tendenzen offenbar. Die Methacrylamid-basierte Polysulfobetaine besitzen eine höhere Phasenübergangstemperatur als ihre Methacrylat-basierten Analoga. Die Vergrößerung der Distanz zwischen Polymerrückrat und der zwitterionischen Gruppe von 2 auf 3 Methylengruppen führt zu einer Erniedrigung der Phasenübergangstemperatur. Polysulfobetaine mit aliphatischen Resten (Methyl-gruppen) am Ammonium-Ion haben eine höhere Phasenübergangstemperatur als ihre Analoga, in denen der Ammonium-Stickstoff Teil eines Heterozyklus ist. Als letzte Strukturvariable wurde die Distanz zwischen Kation und Anion von 3 auf 4 Methylengruppen vergrößert; diese Änderung führt zu einer massiven Erhöhung der Phasenübergangstemperatur. Die Polysulfobetaine wurden verwendet, um mit dem nicht-ionischen Monomer NIPMAM wasserlösliche Blockcopolymere mittels der RAFT Polymerisation herzustellen. Diese Blockcopolymere besitzen doppelt thermisch-responsives Verhalten (mit einem UCST- und einem LCST-Übergang). Die Besonderheit einer solchen Konstellation ist, dass eine Strukturinversion der solvophoben Aggregate induziert werden kann. Daher werden solche Blockcopolymer-Assoziate auch als „schizophrene Mizellen“ bezeichnet. Je nach der relativen Lage der beiden Phasenübergänge, die sich durch Polymerkonzentration oder durch Salzzusatz einstellen lässt, läuft die Strukturinversion über ein molekular gelöstes oder über ein unlösliches Zwischenstadium ab. Der Polysulfobetain-Block bildet bei niedriger Temperatur Aggregate, die durch den gelösten poly(NIPMAM)-Block in Lösung gehalten werden. Dahingegen bildet der poly(NIPMAM)-Block bei hoher Temperatur Aggregate, welche ihrerseits durch den gelösten Polysulfobetain-Block in Lösung gehalten werden. Somit werden „schizophrene“ Aggregate in Wasser erzeugt, die fähig sind, reversibel ihr „Inneres“ nach „Außen“ und umgekehrt zu schalten durch Nutzen eines einfachen thermischen Impulses. KW - switchable block copolymer KW - polyzwitterion KW - polysulfobetaine KW - thermoresponsive polymers KW - schizophrenic behavior KW - LCST and UCST KW - electrolyte sensitivity KW - zweifach schaltbare Blockcopolymere KW - Polyzwitterion KW - Polysulfobetaine KW - thermoresponsive Polymere KW - schizophrenes Verhalten KW - LCST und UCST KW - Elektrolytempfindlichkeit Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-101372 ER - TY - THES A1 - Kovach, Ildiko T1 - Development, characterization of Janus emulsions, and their usage as a template phase for fabricating biopolymer scaffolds Y1 - 2016 ER - TY - THES A1 - Knoop, Mats Timothy T1 - Neue Polyacrylnitril-basierte, schmelzspinnbare Präkursoren für Carbonfasern N2 - Diese Arbeit zu Grunde liegenden Forschung zielte darauf ab, neue schmelzbare Acrylnitril-Copolymere zu entwickeln. Diese sollten im Anschluss über ein Schmelzspinnverfahren zur Chemiefaser geformt und im letzten Schritt zur Carbonfaser konvertiert werden. Zu diesem Zweck wurden zunächst orientierende Untersuchungen an unterschiedlichen Copolymeren des Acrylnitril aus Lösungspolymerisation durchgeführt. Die Untersuchungen zeigten, dass elektrostatische Wechselwirkungen besser als sterische Abschirmung dazu geeignet sind, Schmelzbarkeit unterhalb der Zersetzungstemperatur von Polyacrylnitril zu bewirken. Aus der Vielzahl untersuchter Copolymere stellten sich jene mit Methoxyethylacrylat (MEA) als am effektivsten heraus. Für diese Copolymere wurden sowohl die Copolymerisationsparameter bestimmt als auch die grundlegende Kinetik der Lösungspolymerisation untersucht. Die Copolymere mit MEA wurden über Schmelzspinnen zur Faser umgeformt und diese dann untersucht. Hierbei wurden auch Einflüsse verschiedener Parameter, wie z.B. die der Molmasse, auf die Fasereigenschaften und -herstellung untersucht. Zuletzt wurde ein Heterophasenpolymerisationsverfahren zur Herstellung von Copolymeren aus AN/MEA entwickelt; dadurch konnten die Materialeigenschaften weiter verbessert werden. Zur Unterdrückung der thermoplastischen Eigenschaften der Fasern wurde ein geeignetes Verfahren entwickelt und anschließend die Konversion zu Carbonfasern durchgeführt. N2 - The aim of this work was to develop new meltable acrylonitrile co-polymers. Those should be processed into a fiber via melt-spinning, and finally be converted into carbon fibers. Various co-polymers of acrylonitrile were synthesized by solution polymerization. The investigations showed that electrostatic interactions are more effective than steric shielding for achieving meltability of co-polymers of acrylonitrile. Out of the wide range of co-polymers prepared, those with the co-monomer methoxyethylacrylate were the most effective ones. For these co-polymers copolymerization parameters and basic kinetics were investigated. The co-polymers were processed into fibers via melt-spinning. The influence of various parameters such as molar mass on the process and the mechanical properties of the fibers was studied. Subsequently, a new emulsion polymerization process for the synthesis of the co-polymers was developed, resulting in further improved material properties. Finally a process for deactivation of thermoplasticity by chemical treatment was developed. T2 - Novel meltable polyacrylonitrile precursor for carbon fibres KW - schmelzbares PAN KW - PAN Emulsionspolymerisation KW - meltable PAN KW - Carbonfaserprecursor KW - carbon fibre KW - precursor Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-103972 ER - TY - THES A1 - Draffehn, Sören T1 - Optical Spectroscopy-Based Characterization of Micellar and Liposomal Systems with Possible Applications in Drug Delivery Y1 - 2016 ER - TY - THES A1 - Leiendecker, Mai-Thi T1 - Physikalische Hydrogele auf Polyurethan-Basis T1 - Physical hydrogels based on polyurethanes N2 - Physical hydrogels have gained recent attention as cell substrates, since viscoelasticity or stress relaxation is a powerful parameter in mechanotransduction, which has long been neglected. We designed multi-functional polyurethanes to form physical hydrogels via a unique tunable gelation mechanism. The anionic polyurethanes spontaneously form aggregates in water that are kept in a soluble state through electrostatic repulsion. Fast subsequent gelation can be triggered by charge shielding which allows the aggregation and network building to proceed. This can be induced by adding either acids or salts, resulting in acidic (pH 4-5) or pH-neutral hydrogels, respectively. Whereas conventional polyurethane-based hydrogels are commonly prepared from toxic isocyanate precursors, the physical hydrogelation mechanism described here does not involve chemically reactive species which is ideal for in situ applications in sensitive environments. Both stiffness and stress relaxation can be tuned independently over a broad range and the gels exhibit excellent stress recovery behavior. N2 - Physikalische Hydrogele gewinnen derzeit als Zellsubstrate zunehmend an Interesse, da Viskoelastizität oder Stressrelaxation ein bedeutender Parameter in der Mechanotransduktion ist, der bisher vernachlässigt wurde. In dieser Arbeit wurden multi-funktionelle Polyurethane entworfen, die über einen neuartigen Gelierungsmechanismus physikalische Hydrogele bilden. In Wasser bilden die anionischen Polyurethane spontan Aggregate, welche durch elektrostatische Abstoßung in Lösung gehalten werden. Eine schnelle Gelierung kann von hier aus durch Ladungsabschirmung erreicht werden, wodurch die Aggregation voranschreitet und ein Netzwerk ausgebildet wird. Dies kann durch die Zugabe von verschiedenen Säuren oder Salzen geschehen, sodass sowohl saure (pH 4 - 5) als auch pH-neutrale Hydrogele erhalten werden können. Während konventionelle Hydrogele auf Polyurethan-Basis in der Regel durch toxische isocyanat-haltige Präpolymere hergestellt werden, eignet sich der hier beschriebene physikalische Gelierungsmechanismus für in situ Anwendungen in sensitiven Umgebungen. Sowohl Härte als auch Stressrelaxation der Hydrogele können unabhängig voneinander über einen breiten Bereich eingestellt werden. Darüberhinaus zeichnen sich die Hydrogele durch exzellente Stressregeneration aus. KW - Polyurethane KW - Hydrogele KW - physikalische Hydrogele KW - Kolloidchemie KW - Viskoelastizität KW - Stressrelaxation KW - Stressrelaxierung KW - Bulkgele KW - Mikrogele KW - Mechanotransduktion KW - polyurethanes KW - hydrogels KW - physical hydrogels KW - colloidal chemistry KW - viscoelasticity KW - stress-relaxation KW - stress relaxation KW - bulk gels KW - microgels KW - mechanotransduction Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-103917 ER - TY - THES A1 - König, Jana T1 - Synthese und Charakterisierung von 3d-4f-Komplexen und deren Vorläufer mit 1,2-Dithiooxalat als Ligand Y1 - 2016 ER - TY - JOUR A1 - Schilde, Uwe A1 - Kelling, Alexandra A1 - Umbreen, Sumaira A1 - Linker, Torsten T1 - Crystal structures of three bicyclic carbohydrate derivatives JF - Acta crystallographica Section E ; Crystallographic communications N2 - The title compounds, [(1R,3R,4R,5R,6S)-4,5-bis(acetyloxy)-7-oxo-2-oxabicyclo- [4.2.0]octan-3-yl]methyl acetate, C14H18O8, (I), [(1S,4R,5S,6R)-5-acetyloxy-7- hydroxyimino-2-oxobicyclo[4.2.0]octan-4-yl acetate, C11H15NO6, (II), and [(3aR,5R,6R,7R,7aS)-6,7-bis(acetyloxy)-2-oxooctahydropyrano[3,2-b]pyrrol-5- yl]methyl acetate, C14H19NO8, (III), are stable bicyclic carbohydrate derivatives. They can easily be synthesized in a few steps from commercially available glycals. As a result of the ring strain from the four-membered rings in (I) and (II), the conformations of the carbohydrates deviate strongly from the ideal chair form. Compound (II) occurs in the boat form. In the five-membered lactam (III), on the other hand, the carbohydrate adopts an almost ideal chair conformation. As a result of the distortion of the sugar rings, the configurations of the three bicyclic carbohydrate derivatives could not be determined from their NMR coupling constants. From our three crystal structure determinations, we were able to establish for the first time the absolute configurations of all new stereocenters of the carbohydrate rings. KW - crystal structure KW - carbohydrate deriv­atives KW - conformation KW - configuration Y1 - 2016 U6 - https://doi.org/10.1107/S2056989016018727 SN - 2056-9890 VL - 72 IS - 12 SP - 1839 EP - 1844 PB - IUCR CY - Chester ER - TY - GEN A1 - Schilde, Uwe A1 - Kelling, Alexandra A1 - Umbreen, Sumaira A1 - Linker, Torsten T1 - Crystal structures of three bicyclic carbohydrate derivatives N2 - The title compounds, [(1R,3R,4R,5R,6S)-4,5-bis­(acet­yloxy)-7-oxo-2-oxabi­cyclo[4.2.0]octan-3-yl]methyl acetate, C14H18O8, (I), [(1S,4R,5S,6R)-5-acet­yloxy-7-hy­droxy­imino-2-oxobi­cyclo­[4.2.0]octan-4-yl acetate, C11H15NO6, (II), and [(3aR,5R,6R,7R,7aS)-6,7-bis­(acet­yloxy)-2-oxo­octa­hydro­pyrano[3,2-b]pyrrol-5-yl]methyl acetate, C14H19NO8, (III), are stable bicyclic carbohydrate derivatives. They can easily be synthesized in a few steps from commercially available glycals. As a result of the ring strain from the four-membered rings in (I) and (II), the conformations of the carbohydrates deviate strongly from the ideal chair form. Compound (II) occurs in the boat form. In the five-membered lactam (III), on the other hand, the carbohydrate adopts an almost ideal chair conformation. As a result of the distortion of the sugar rings, the configurations of the three bicyclic carbohydrate derivatives could not be determined from their NMR coupling constants. From our three crystal structure determinations, we were able to establish for the first time the absolute configurations of all new stereocenters of the carbohydrate rings. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 296 KW - crystal structure KW - carbohydrate deriv­atives KW - conformation KW - configuration Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-100833 ER - TY - THES A1 - Limberg, Felix Rolf Paul T1 - Synthese und Entwicklung thermisch vernetzbarer OLED-Materialien Y1 - 2016 ER - TY - THES A1 - Rackwitz, Jenny T1 - A novel approach to study low-energy electron-induced damage to DNA oligonucleotides BT - Influence of DNA sequence, topology and nucleobase modification Y1 - 2016 ER - TY - JOUR A1 - Villatoro, José Andrés A1 - Zühlke, Martin A1 - Riebe, Daniel A1 - Riedel, Jens A1 - Beitz, Toralf A1 - Löhmannsröben, Hans-Gerd T1 - IR-MALDI ion mobility spectrometry JF - Analytical and bioanalytical chemistry : a merger of Fresenius' journal of analytical chemistry and Analusis N2 - The novel combination of infrared matrix-assisted laser dispersion and ionization (IR-MALDI) with ion mobility (IM) spectrometry makes it possible to investigate biomolecules in their natural environment, liquid water. As an alternative to an ESI source, the IR-MALDI source was implemented in an in-house-developed ion mobility (IM) spectrometer. The release of ions directly from an aqueous solution is based on a phase explosion, induced by the absorption of an IR laser pulse (lambda = 2.94 mu m, 6 ns pulse width), which disperses the liquid as nano- and micro-droplets. The prerequisites for the application of IR-MALDI-IM spectrometry as an analytical method are narrow analyte ion signal peaks for a high spectrometer resolution. This can only be achieved by improving the desolvation of ions. One way to full desolvation is to give the cluster ions sufficient time to desolvate. Two methods for achieving this are studied: the implementation of an additional drift tube, as in ESI-IM-spectrometry, and the delayed extraction of the ions. As a result of this optimization procedure, limits of detection between 5 nM and 2.5 mu M as well as linear dynamic ranges of 2-3 orders of magnitude were obtained for a number of substances. The ability of this method to analyze simple mixtures is illustrated by the separation of two different surfactant mixtures. KW - Ion mobility spectrometry KW - IR-MALDI KW - Laser Y1 - 2016 U6 - https://doi.org/10.1007/s00216-016-9739-x SN - 1618-2642 SN - 1618-2650 VL - 408 SP - 6259 EP - 6268 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Villatoro, José Andrés A1 - Zühlke, Martin A1 - Riebe, Daniel A1 - Beitz, Toralf A1 - Weber, Marcus A1 - Riedel, Jens A1 - Löhmannsröben, Hans-Gerd T1 - IR-MALDI ion mobility spectrometry: physical source characterization and application as HPLC detector JF - International journal for ion mobility spectrometry : official publication of the International Society for Ion Mobility Spectrometry N2 - Infrared matrix-assisted laser dispersion and ionization (IR-MALDI) in combination with ion mobility (IM) spectrometry enables the direct analysis of biomolecules in aqueous solution. The release of ions directly from an aqueous solution is based on a phase explosion, induced by the absorption of an IR laser pulse, which disperses the liquid as vapor, nano-and micro-droplets. The ionization process is characterized initially by a broad spatial distribution of the ions, which is a result of complex fluid dynamics and desolvation kinetics. These processes have a profound effect on the shape and width of the peaks in the IM spectra. In this work, the transport of ions by the phase explosion-induced shockwave could be studied independently from the transport by the electric field. The shockwave-induced mean velocities of the ions at different time scales were determined through IM spectrometry and shadowgraphy. The results show a deceleration of the ions from 118 m.s(-1) at a distance of 400 mu m from the liquid surface to 7.1 m.s(-1) at a distance of 10 mm, which is caused by a pile-up effect. Furthermore, the desolvation kinetics were investigated and a first-order desolvation constant of 325 +/- 50 s(-1) was obtained. In the second part, the IR-MALDI-IM spectrometer is used as an HPLC detector for the two-dimensional separation of a pesticide mixture. KW - Ion mobility spectrometry KW - IR-MALDI KW - Shadowgraphy KW - Laser KW - Imaging KW - HPLC Y1 - 2016 U6 - https://doi.org/10.1007/s12127-016-0208-1 SN - 1435-6163 SN - 1865-4584 VL - 19 SP - 197 EP - 207 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Rottke, Falko O. A1 - Schulz, Burkhard A1 - Richau, Klaus A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers JF - Beilstein journal of nanotechnology N2 - The applicability of nulling-based ellipsometric mapping as a complementary method next to Brewster angle microscopy (BAM) and imaging ellipsometry (IE) is presented for the characterization of ultrathin films at the air-water interface. First, the methodology is demonstrated for a vertically nonmoving Langmuir layer of star-shaped, 4-arm poly(omega-pentadecalactone) (PPDL-D4). Using nulling-based ellipsometric mapping, PPDL-D4-based inhomogeneously structured morphologies with a vertical dimension in the lower nm range could be mapped. In addition to the identification of these structures, the differentiation between a monolayer and bare water was possible. Second, the potential and limitations of this method were verified by applying it to more versatile Langmuir layers of telechelic poly[(rac-lactide)-co-glycolide]-diol (PLGA). All ellipsometric maps were converted into thickness maps by introduction of the refractive index that was derived from independent ellipsometric experiments, and the result was additionally evaluated in terms of the root mean square roughness, R-q. Thereby, a three-dimensional view into the layers was enabled and morphological inhomogeneity could be quantified. KW - ellipsometric mapping KW - Langmuir monolayer KW - polyester KW - root mean square roughness KW - spectroscopic ellipsometry Y1 - 2016 U6 - https://doi.org/10.3762/bjnano.7.107 SN - 2190-4286 VL - 7 SP - 1156 EP - 1165 PB - Beilstein-Institut zur Förderung der Chemischen Wissenschaften CY - Frankfurt, Main ER - TY - JOUR A1 - Rossberg, Joana A1 - Rottke, Falko O. A1 - Schulz, Burkhard A1 - Lendlein, Andreas T1 - Enzymatic Degradation of Oligo(epsilon-caprolactone)s End-Capped with Phenylboronic Acid Derivatives at the Air-Water Interface JF - Macromolecular rapid communications N2 - The influence of terminal functionalization of oligo(epsilon-caprolactone)s (OCL) with phenylboronic acid pinacol ester or phenylboronic acid on the enzymatic degradation behavior at the air-water interface is investigated by the Langmuir monolayer degradation technique. While the unsubstituted OCL immediately degrades after injection of the enzyme lipase from Pseudomonas cepacia, enzyme molecules are incorporated into the films based on end-capped OCL before degradation. This incorporation of enzymes does not inhibit or suppress the film degradation, but retards it significantly. A specific binding of lipase to the polymer monolayer allows studying the enzymatic activity of bound proteins and the influence on the degradation process. The functionalization of a macromolecule with phenyl boronic acid groups is an approach to investigate their interactions with diol-containing biomolecules like sugars and to monitor their specified impact on the enzymatic degradation behavior at the air-water interface. Y1 - 2016 U6 - https://doi.org/10.1002/marc.201600471 SN - 1022-1336 SN - 1521-3927 VL - 37 SP - 1966 EP - 1971 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Andrews, Nicholas L. P. A1 - Ross, Rachel A1 - Munzke, Dorit A1 - van Hoorn, Camiel A1 - Brzezinski, Andrew A1 - Barnes, Jack A. A1 - Reich, Oliver A1 - Loock, Hans-Peter T1 - In-fiber Mach-Zehnder interferometer for gas refractive index measurements based on a hollow-core photonic crystal fiber JF - Optics express : the international electronic journal of optics N2 - We describe an in-fiber interferometer based on a gas-filled hollow-core photonic crystal fiber. Expressions for the sensitivity, figure of merit and refractive index resolution are derived, and values are experimentally measured and theoretically validated using mode field calculations. The refractive indices of nine monoatomic and molecular gases are measured with a resolution of delta(ns) < 10(-6). (C)2016 Optical Society of America Y1 - 2016 U6 - https://doi.org/10.1364/OE.24.014086 SN - 1094-4087 VL - 24 SP - 14086 EP - 14099 PB - Optical Society of America CY - Washington ER - TY - JOUR A1 - Schmidt, Burkhard A1 - Lorenz, Ulf T1 - WavePacket BT - a Matlab package for numerical quantum dynamics. I: Closed quantum systems and discrete variable representations JF - Computer physics communications : an international journal devoted to computational physics and computer programs in physics N2 - WavePacket is an open-source program package for the numerical simulation of quantum-mechanical dynamics. It can be used to solve time-independent or time-dependent linear Schrödinger and Liouville–von Neumann-equations in one or more dimensions. Also coupled equations can be treated, which allows to simulate molecular quantum dynamics beyond the Born–Oppenheimer approximation. Optionally accounting for the interaction with external electric fields within the semiclassical dipole approximation, WavePacket can be used to simulate experiments involving tailored light pulses in photo-induced physics or chemistry. The graphical capabilities allow visualization of quantum dynamics ‘on the fly’, including Wigner phase space representations. Being easy to use and highly versatile, WavePacket is well suited for the teaching of quantum mechanics as well as for research projects in atomic, molecular and optical physics or in physical or theoretical chemistry. The present Part I deals with the description of closed quantum systems in terms of Schrödinger equations. The emphasis is on discrete variable representations for spatial discretization as well as various techniques for temporal discretization. The upcoming Part II will focus on open quantum systems and dimension reduction; it also describes the codes for optimal control of quantum dynamics. The present work introduces the MATLAB version of WavePacket 5.2.1 which is hosted at the Sourceforge platform, where extensive Wiki-documentation as well as worked-out demonstration examples can be found. KW - Schrodinger equation KW - Quantum dynamics KW - Numerical propagation KW - Bound states KW - Discrete variable representation KW - Non-adiabatic transitions Y1 - 0207 U6 - https://doi.org/10.1016/j.cpc.2016.12.007 SN - 0010-4655 SN - 1879-2944 VL - 213 SP - 223 EP - 234 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Balderas-Valadez, Ruth Fabiola A1 - Agarwal, Vivechana A1 - Pacholski, Claudia T1 - Fabrication of porous silicon-based optical sensors using metal-assisted chemical etching JF - RSC Advances N2 - Optical biosensors based on porous silicon were fabricated by metal assisted chemical etching. Thereby double layered porous silicon structures were obtained consisting of porous pillars with large pores on top of a porous silicon layer with smaller pores. These structures showed a similar sensing performance in comparison to electrochemically produced porous silicon interferometric sensors. Y1 - 2016 U6 - https://doi.org/10.1039/c5ra26816h SN - 2046-2069 VL - 6 SP - 21430 EP - 21434 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Couturier, Jean-Philippe A1 - Wischerhoff, Erik A1 - Bernin, Robert A1 - Hettrich, Cornelia A1 - Koetz, Joachim A1 - Sutterlin, Martin A1 - Tiersch, Brigitte A1 - Laschewsky, Andre T1 - Thermoresponsive Polymers and Inverse Opal Hydrogels for the Detection of Diols JF - Langmuir N2 - Responsive inverse opal hydrogels functionalized by boroxole moieties were synthesized and explored as sensor platforms for various low molar mass as well as polymeric diols and polyols, including saccharides, glycopolymers and catechols, by exploiting the diol induced modulation of their structural color. The underlying thermoresponsive water-soluble copolymers and hydrogels exhibit a coil-to-globule or volume phase transition, respectively, of the LCST-type. They were prepared from oligoethylene oxide methacrylate (macro)monomers and functionalized via copolymerization to bear benzoboroxole moieties. The resulting copolymers represent weak polyacids, which can bind specifically to diols within an appropriate pH window. Due to the resulting modulation of the overall hydrophilicity of the systems and the consequent shift of their phase transition temperature, the usefulness of such systems for indicating the presence of catechols, saccharides, and glycopolymers was studied, exploiting the diol/polyol induced shifts of the soluble polymers’ cloud point, or the induced changes of the hydrogels’ swelling. In particular, the increased acidity of benzoboroxoles compared to standard phenylboronic acids allowed performing the studies in PBS buffer (phosphate buffered saline) at the physiologically relevant pH of 7.4. The inverse opals constructed of these thermo- and analyte-responsive hydrogels enabled following the binding of specific diols by the induced shift of the optical stop band. Their highly porous structure enabled the facile and specific optical detection of not only low molar mass but also of high molar mass diol/polyol analytes such as glycopolymers. Accordingly, such thermoresponsive inverse opal systems functionalized with recognition units represent attractive and promising platforms for the facile sensing of even rather big analytes by simple optical means, or even by the bare eye. Y1 - 2016 U6 - https://doi.org/10.1021/acs.langmuir.6b00803 SN - 0743-7463 VL - 32 SP - 4333 EP - 4345 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Vargas-Ruiz, Salome A1 - Schulreich, Christoph A1 - Kostevic, Angelika A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Kakorin, Sergej A1 - von Klitzing, Regine A1 - Jung, Martin A1 - Hellweg, Thomas A1 - Wellert, Stefan T1 - Extraction of model contaminants from solid surfaces by environmentally compatible microemulsions JF - Journal of colloid and interface science N2 - In the present contribution, we evaluate the efficiency of eco-friendly microemulsions to decontaminate solid surfaces by monitoring the extraction of non-toxic simulants of sulfur mustard out of model surfaces. The extraction process of the non-toxic simulants has been monitored by means of spectroscopic and chromatographic techniques. The kinetics of the removal process was analyzed by different empirical models. Based on the analysis of the kinetics, we can assess the influence of the amounts of oil and water and the microemulsion structure on the extraction process. (C) 2016 Elsevier Inc. All rights reserved. KW - Microemulsions KW - Decontamination KW - Surface removal KW - Kinetic analysis KW - Extraction Y1 - 2016 U6 - https://doi.org/10.1016/j.jcis.2016.03.006 SN - 0021-9797 SN - 1095-7103 VL - 471 SP - 118 EP - 126 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Wessig, Pablo A1 - Gerngross, Maik A1 - Freyse, Daniel A1 - Bruhn, P. A1 - Przezdziak, Marc A1 - Schilde, Uwe A1 - Kelling, Alexandra T1 - Molecular Rods Based on Oligo-spiro-thioketals JF - The journal of organic chemistry N2 - We report on an extension of the previously established concept of oligospiroketal (OSK) rods by replacing a part or all ketal moieties by thioketals leading to oligospirothioketal (OSTK) rods. In this way, some crucial problems arising from the reversible formation of ketals are circumvented. Furthermore, the stability of the rods toward hydrolysis is considerably improved. To successfully implement this concept, we first developed a number of new oligothiol building blocks and improved the synthetic accessibility of known oligothiols, respectively. Another advantage of thioacetals is that terephthalaldehyde (TAA) sleeves, which are too flexible in the case of acetals can be used in OSTK rods. The viability of the OSTK approach was demonstrated by the successful preparation of some OSTK rods with a length of some nanometers. Y1 - 2016 U6 - https://doi.org/10.1021/acs.joc.5b02670 SN - 0022-3263 VL - 81 SP - 1125 EP - 1136 PB - American Chemical Society CY - Washington ER - TY - GEN A1 - Schulze, Nicole A1 - Koetz, Joachim T1 - Kinetically Controlled Growth of Gold Nanotriangles in a Vesicular Template Phase by Adding a Strongly Alternating Polyampholyte N2 - This paper is focused on the temperature dependent synthesis of gold nanotriangles in a vesicular template phase, containing phosphatidylcholin and AOT, by adding the strongly alternating polyampholyte PalPhBisCarb. UV-vis absorption spectra in combination with TEM micrographs show that flat gold nanoplatelets are formed predominantly in presence of the polyampholyte at 45 °C. The formation of triangular and hexagonal nanoplatelets can be directly influenced by the kinetic approach, i.e., by varying the polyampholyte dosage rate at 45 °C. Corresponding zeta potential measurements indicate that a temperature dependent adsorption of the polyampholyte on the {111} faces will induce the symmetry breaking effect, which is responsible for the kinetically controlled hindered vertical and preferred lateral growth of the nanoplatelets. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 271 KW - Polyampholytes KW - Nanotriangles KW - Kinetically controlled nanocrystal growth Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-98380 ER - TY - JOUR A1 - Kopec, Maciej A1 - Rozpedzik, Anna A1 - Lapok, Lukasz A1 - Geue, Thomas A1 - Laschewsky, Andre A1 - Zapotoczny, Szczepan T1 - Stratified Micellar Multilayers-Toward Nanostructured Photoreactors JF - Chemistry of materials : a publication of the American Chemical Society N2 - Polyelectrolyte multilayers (PEMs) with stratification of the internal structure were assembled from statistical amphiphilic copolyelectrolytes of opposite charges. These polyelectrolytes organize in aqueous solutions into micellar structures with fluoroalkyl and aromatic nanodomains, respectively, that were also preserved after deposition as thin films via layer-by-layer (LbL) electrostatic self-assembly. The unimolecular micelles, formed due to statistical compositions of amphiphilic polyelectrolytes used, were shown to suppress chain interdiffusion between adjacent layers in resulting micellar PEMs, as evidenced by spectroscopic ellipsometry, atomic force microscopy (AFM), and neutron reflectometry (NR) measurements. Additionally, hydrophobic cores of the micelles were used as hosts for photoactive molecules, namely, ferrocene and perfluorinated magnesium phthalocyanine. Stratified micellar multilayers were then deposited as hollow capsules using CaCO3 microparticles as templates. Photoinduced electron transfer (PET) between ferrocene and phthalocyanine solubilized in the polymer micelles was demonstrated to occur efficiently inside the stratified, polyelectrolyte walls of the capsules, due to the polarity gradient created by the incompatible aromatic and fluoroalkyl domains. The obtained results present a new approach to construct well-organized, self-assembled nanostructured materials for solar energy conversion. Y1 - 2016 U6 - https://doi.org/10.1021/acs.chemmater.6b00161 SN - 0897-4756 SN - 1520-5002 VL - 28 SP - 2219 EP - 2228 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Bernd A1 - Riemer, Martin T1 - Microwave-Promoted Deprenylation: Prenyl Ether as a Thermolabile Phenol Protecting Group JF - Synthesis N2 - para-Substituted aryl prenyl ethers undergo a deprenylation reaction upon microwave irradiation. This offers the opportunity to use a prenyl ether as a thermolabile protecting group in the synthesis of natural products with a chromone structure, which proceeds via a tandem deprenylation/6-endo-cyclization sequence. KW - microwave irradiation KW - phenols KW - chromenes KW - protecting groups KW - Claisen rearrangement Y1 - 2016 U6 - https://doi.org/10.1055/s-0035-1561366 SN - 0039-7881 SN - 1437-210X VL - 48 SP - 1399 EP - 1406 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Dietrich, Paul M. A1 - Glamsch, Stephan A1 - Ehlert, Christopher A1 - Lippitz, Andreas A1 - Kulak, Nora A1 - Unger, Wolfgang E. S. T1 - Synchrotron-radiation XPS analysis of ultra-thin silane films: Specifying the organic silicon JF - Applied surface science : a journal devoted to applied physics and chemistry of surfaces and interfaces N2 - The analysis of chemical and elemental in-depth variations in ultra-thin organic layers with thicknesses below 5 nm is very challenging. Energy- and angle-resolved XPS (ER/AR-XPS) opens up the possibility for non-destructive chemical ultra-shallow depth profiling of the outermost surface layer of ultra-thin organic films due to its exceptional surface sensitivity. For common organic materials a reliable chemical in-depth analysis with a lower limit of the XPS information depth z(95) of about 1 nm can be performed. As a proof-of-principle example with relevance for industrial applications the ER/AR-XPS analysis of different organic monolayers made of amino- or benzamidosilane molecules on silicon oxide surfaces is presented. It is demonstrated how to use the Si 2p core-level region to non-destructively depth-profile the organic (silane monolayer) - inorganic (SiO2/Si) interface and how to quantify Si species, ranging from elemental silicon over native silicon oxide to the silane itself. The main advantage of the applied ER/AR-XPS method is the improved specification of organic from inorganic silicon components in Si 2p core-level spectra with exceptional low uncertainties compared to conventional laboratory XPS. (C) 2015 Elsevier B.V. All rights reserved. KW - Synchrotron radiation XPS KW - Depth profiling KW - Silanes KW - Monolayer KW - Amines KW - Amides Y1 - 2016 U6 - https://doi.org/10.1016/j.apsusc.2015.12.052 SN - 0169-4332 SN - 1873-5584 VL - 363 SP - 406 EP - 411 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Tetali, Sarada D. A1 - Jankowski, Vera A1 - Luetzow, Karola A1 - Kratz, Karl A1 - Lendlein, Andreas A1 - Jankowski, Joachim T1 - Adsorption capacity of poly(ether imide) microparticles to uremic toxins JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - Uremia is a phenomenon caused by retention of uremic toxins in the plasma due to functional impairment of kidneys in the elimination of urinary waste products. Uremia is presently treated by dialysis techniques like hemofiltration, dialysis or hemodiafiltration. However, these techniques in use are more favorable towards removing hydrophilic than hydrophobic uremic toxins. Hydrophobic uremic toxins, such as hydroxy hipuric acid (OH-HPA), phenylacetic acid (PAA), indoxyl sulfate (IDS) and p-cresylsulfate (pCRS), contribute substantially to the progression of chronic kidney disease (CKD) and cardiovascular disease. Therefore, objective of the present study is to test adsorption capacity of highly porous microparticles prepared from poly(ether imide) (PEI) as an alternative technique for the removal of uremic toxins. Two types of nanoporous, spherically shaped microparticles were prepared from PEI by a spraying/coagulation process. PEI particles were packed into a preparative HPLC column to which a mixture of the four types of uremic toxins was injected and eluted with ethanol. Eluted toxins were quantified by analytical HPLC. PEI particles were able to adsorb all four toxins, with the highest affinity for PAA and pCR. IDS and OH-HPA showed a partially non-reversible binding. In summary, PEI particles are interesting candidates to be explored for future application in CKD. KW - Adsorption of uremic toxins KW - chronic kidney disease (CKD) KW - hydrophobic uremic toxins KW - poly(ether imide) KW - microparticles KW - uremia Y1 - 2016 U6 - https://doi.org/10.3233/CH-152026 SN - 1386-0291 SN - 1875-8622 VL - 61 SP - 657 EP - 665 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Kumar, Reddi K. A1 - Basu, Sayantani A1 - Lemke, Horst-Dieter A1 - Jankowski, Joachim A1 - Kratz, Karl A1 - Lendlein, Andreas A1 - Tetali, Sarada D. T1 - Effect of extracts of poly(ether imide) microparticles on cytotoxicity, ROS generation and proinflammatory effects on human monocytic (THP-1) cells JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - A high cell viability of around 99 +/- 18% and 99 +/- 5% was observed when THP-1 cells were cultured in the presence of aqueous extracts of the PEI microparticles in medium A and medium B respectively. The obtained microscopic data suggested that PEI particle extracts have no significant effect on cell death, oxidative stress or differentiation to macrophages. It was further found that the investigated proinflammatory markers in THP-1 cells were not up-regulated. These results are promising with regard to the biocompatibility of PEI microparticles and in a next step the hemocompatibility of the microparticles will be examined. KW - Chronic kidney disease (CKD) KW - cytotoxicity KW - human monocytic (THP-1) cells KW - poly(ether imide) microparticles KW - reactive oxygen species (ROS) Y1 - 2016 U6 - https://doi.org/10.3233/CH-152027 SN - 1386-0291 SN - 1875-8622 VL - 61 SP - 667 EP - 680 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Baraza, Lilechi D. A1 - Neser, Wekesa A1 - Jackson, Korir Cheruiyot A1 - Fredrick, Juma B. A1 - Dennis, Ochieno A1 - Wairimu, Kamau R. A1 - Keya, Aggrey Osogo A1 - Heydenreich, Matthias T1 - Antimicrobial Coumarins from the Oyster Culinary-Medicinal Mushroom, Pleurotus ostreatus (Agaricomycetes), from Kenya JF - International journal of medicinal mushrooms N2 - Pleurotus ostreatus has been widely used as food because of its nutritional and medicinal properties. These have been attributed to the presence of macronutrients, minerals, vitamins, and amino acids, among other secondary metabolites. There are, however, few reports on the antimicrobial activities of different classes of purified compounds from P. ostreatus. This led to the current study, the objective of which was to chemically characterize the antibiotic activities of P. ()streams against selected human pathogenic bacteria and endophytic fungi. Chemical structures were determined using spectroscopic methods and by comparison with values of related structures reported in the literature. Pure compounds from P. ostreatus were tested in vitro against pathogenic bacteria (Staphylococcus aureus and Escherichia coli) and endophytic fungi (Pencillium digitatum and Fusarium prolferatum). A new compound, (E)-5,7-dimethoxy-6-(3-methylbuta-1,3-dienyl)-2H-chromen-2-one (5-methoxy-(E)-suberodiene) (compound 2), along with ergosterol (compound I.) and 5,7-dimethoxy-6-(3-methylbut-2-enyl)-2H-chromen-2-one (toddaculin; compound 3), were isolated from the fruiting bodies of P. ostreatus. The growth of S. aureus,E proliferatum, and P. digitatum colonies was inhibited in media containing compound 2, with minimum inhibitory concentrations closely comparable to those of conventional antibiotics. KW - Escherichia coli KW - Fusarium proliferatum KW - medicinal mushrooms KW - Penicillium digitatum KW - Pleurotus ostreatus KW - Staphylococcus aureus Y1 - 2016 U6 - https://doi.org/10.1615/IntJMedMushrooms.v18.i10.60 SN - 1521-9437 SN - 1940-4344 VL - 18 SP - 905 EP - 913 PB - Begell House CY - Danbury ER - TY - JOUR A1 - Strauch, Peter A1 - Kossmann, Alexander A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - EPR on bis(1,2-dithiosquarato)cuprate(II) in the bis(1,2-dithiosquarato)nickelate(II) host lattice - structure and spectroscopy JF - Chemical papers N2 - EPR spectroscopy is a well suited analytical tool to monitor the electronic situation around paramagnetic metal centres as copper(II) and therefore the structural influences on the paramagnetic ion. 1,2-Dithiosquaratometalates are available by direct synthesis from metal salts with dipotassium-1,2-dithiosquarate and the appropriate counter cations. Synthesis and characterisation of bis(benzyltributylammonium)1,2-dithiosquaratonickelate(II), (BzlBu(3)N)(2)[Ni(dtsq)(2)], and bis(benzyltributylammonium)1,2-dithiosquaratocuprate(II), (BzlBu(3)N)(2)[Cu(dtsq)(2)], with benzyltributylammonium as the counter ion is reported and the X-ray structures of two complexes, (BzlBu(3)N)(2)[Ni(dtsq)(2)] and (BzlBu(3)N)(2)[Cu(dtsq)(2)], are presented. Both complexes, crystallising in the monoclinic space group P2(1)/c, are isostructural with only small differences in the coordination sphere due to the different metal ions. The diamagnetic nickel complex is therefore well suited as a host lattice for the paramagnetic Cu(II) complex to measure EPR for additional structural information. (c) 2015 Institute of Chemistry, Slovak Academy of Sciences KW - 1,2-dithiosquarate KW - 1,2-dithiosquaratometalate KW - X-ray structure KW - EPR spectroscopy Y1 - 2016 U6 - https://doi.org/10.1515/chempap-2015-0154 SN - 0366-6352 SN - 1336-9075 VL - 70 SP - 61 EP - 68 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - von Reppert, Alexander A1 - Sarhan, Radwan Mohamed A1 - Stete, Felix A1 - Pudell, Jan-Etienne A1 - Del Fatti, N. A1 - Crut, A. A1 - Koetz, Joachim A1 - Liebig, Ferenc A1 - Prietzel, Claudia Christina A1 - Bargheer, Matias T1 - Watching the Vibration and Cooling of Ultrathin Gold Nanotriangles by Ultrafast X-ray Diffraction JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - We study the vibrations of ultrathin gold nanotriangles upon optical excitation of the electron gas by ultrafast X-ray diffraction. We quantitatively measure the strain evolution in these highly asymmetric nano-objects, providing a direct estimation of the amplitude and phase of the excited vibrational motion. The maximal strain value is well reproduced by calculations addressing pump absorption by the nanotriangles and their resulting thermal expansion. The amplitude and phase of the out-of-plane vibration mode with 3.6 ps period dominating the observed oscillations are related to two distinct excitation mechanisms. Electronic and phonon pressures impose stresses with different time dependences. The nanosecond relaxation of the expansion yields a direct temperature sensing of the nano-object. The presence of a thin organic molecular layer at the nanotriangle/substrate interfaces drastically reduces the thermal conductance to the substrate. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpcc.6b11651 SN - 1932-7447 VL - 120 SP - 28894 EP - 28899 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Herfurth, Christoph A1 - Laschewsky, Andre A1 - Noirez, Laurence A1 - von Lospichl, Benjamin A1 - Gradzielski, Michael T1 - Thermoresponsive (star) block copolymers from one-pot sequential RAFT polymerizations and their self-assembly in aqueous solution JF - Polymer : the international journal for the science and technology of polymers N2 - A series of hydrophobically end-capped linear triblock copolymers as well as of three-arm and four-arm star block copolymers was synthesized in a one-pot procedure from N,N-dimethylacrylamide (DMA) and N, N-diethylacrylamide (DEA). The sequential reversible addition-fragmentation chain transfer (RAFT) polymerization of these monomers via the R-approach using bi-, tri- and tetrafunctional chain transfer agents (CrAs) bearing hydrophobic dodecyl moieties proceeded in a well-controlled manner up to almost quantitative conversion. Polymers with molar masses up to 150 kDa, narrow molar mass distribution (PDI <= 1.3) and high end group functionality were obtained, which are thermoresponsive in aqueous solution showing a LCST (lower critical solution temperature) transition. The temperature-dependent associative behavior of the polymers was examined using turbidimetry, static and dynamic light scattering (SLS, DLS), and small angle neutron scattering (SANS) for structural analysis. At 25 degrees C, the polymers form weak transient networks, and rather small hydrophobic domains are already present for polymer concentrations of 5 wt%. However, when heating above the LCST transition (35-40 degrees C) of the PDEA blocks, the enhanced formation of hydrophobic domains is observed by means of light and neutron scattering. These domains have a size of about 12-15 nm and must be effectively physically cross-linked as they induce high viscosity for the more concentrated samples. SANS shows that these domains are ordered as evidenced by the appearance of a correlation peak. The copolymer architecture affects in particular the extent of ordering as the four-arm star block copolymer shows much more repulsive interactions compared to the analogous copolymers with a lower number of arms. (C) 2016 Elsevier Ltd. All rights reserved. KW - RAFT polymerization KW - Block copolymers KW - Thermosensitivity KW - LCST KW - SANS KW - Light scattering Y1 - 2016 U6 - https://doi.org/10.1016/j.polymer.2016.09.089 SN - 0032-3861 SN - 1873-2291 VL - 107 SP - 422 EP - 433 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Schmidt, Bernd A1 - Audoersch, Stephan A1 - Kunz, Oliver T1 - Stereoselective Synthesis of 2Z,4E-Configured Dienoates through Tethered Ring Closing Metathesis JF - Synthesis KW - allyl alcohols KW - dienes KW - ring closing metathesis KW - ruthenium KW - elimination Y1 - 2016 U6 - https://doi.org/10.1055/s-0035-1562536 SN - 0039-7881 SN - 1437-210X VL - 48 SP - 4509 EP - 4518 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Schöne, Anne-Christin A1 - Schulz, Burkhard A1 - Lendlein, Andreas T1 - Stimuli Responsive and Multifunctional Polymers: Progress in Materials and Applications JF - Macromolecular rapid communications Y1 - 2016 U6 - https://doi.org/10.1002/marc.201600650 SN - 1022-1336 SN - 1521-3927 VL - 37 SP - 1856 EP - 1859 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schilde, Uwe A1 - Kelling, Alexandra A1 - Umbreen, Sumaira A1 - Linker, Torsten T1 - Crystal structures of three bicyclic carbohydrate derivatives JF - Acta crystallographica, Section E, Crystallographic communications N2 - The title compounds, [(1R,3R,4R,5R,6S)-4,5-bis(acetyloxy)-7-oxo-2-oxabicyclo-[4.2.0]octan-3-yl]methyl acetate, C14H18O8, (I), [(1S,4R,5S,6R)-5-acetyloxy-7-hydroxyimino-2-oxobicyclo[4.2.0] octan-4-yl acetate, C11H15NO6, (II), and [(3aR, 5R, 6R, 7R, 7aS)-6,7-bis(acetyloxy)-2-oxooctahydropyrano[3,2-b]pyrrol-5-yl] methyl acetate, C14H19NO8, (III), are stable bicyclic carbohydrate derivatives. They can easily be synthesized in a few steps from commercially available glycals. As a result of the ring strain from the four-membered rings in (I) and (II), the conformations of the carbohydrates deviate strongly from the ideal chair form. Compound (II) occurs in the boat form. In the five-membered lactam (III), on the other hand, the carbohydrate adopts an almost ideal chair conformation. As a result of the distortion of the sugar rings, the configurations of the three bicyclic carbohydrate derivatives could not be determined from their NMR coupling constants. From our three crystal structure determinations, we were able to establish for the first time the absolute configurations of all new stereocenters of the carbohydrate rings. KW - crystal structure KW - carbohydrate derivatives KW - conformation KW - configuration Y1 - 2016 U6 - https://doi.org/10.1107/S2056989016018727 SN - 2056-9890 VL - 72 SP - 1839 EP - + PB - International Union of Crystallography CY - Chester ER - TY - JOUR A1 - Ryabchun, Alexander A1 - Raguzin, Ivan A1 - Stumpe, Joachim A1 - Shibaev, Valery A1 - Bobrovsky, Alexey T1 - Cholesteric Polymer Scaffolds Filled with Azobenzene-Containing Nematic Mixture with Phototunable Optical Properties JF - Scientific reports N2 - The past two decades witnessed tremendous progress in the field of creation of different types of responsive materials. Cholesteric polymer networks present a very promising class of smart materials due to the combination of the unique optical properties of cholesteric mesophase and high mechanical properties of polymer networks. In the present work we demonstrate the possibility of fast and reversible photocontrol of the optical properties of cholesteric polymer networks. Several cholesteric photopolymerizable mixtures are prepared, and porous cholesteric network films with different helix pitches are produced by polymerization of these mixtures. An effective and simple method of the introduction of photochromic azobenzene-containing nematic mixture capable of isothermal photoinducing the nematic isotropic phase transition into the porous polymer matrix is developed, It is found that cross-linking density and degree of polymer network filling with a photochromic nematic mixture strongly influence the photo-optical behavior of the obtained composite films. In particular, the densely cross-linked films are characterized by a decrease in selective light reflection bandwidth, whereas weakly cross-linked systems display two processes: the shift of selective light reflection peak and decrease of its width. It is noteworthy that the obtained cholesteric materials are shown to be very promising for the variety applications in optoelectronics and photonics. KW - liquid crystalline polymer KW - azobenzene KW - cholesteric phase KW - phototunable optical properties KW - selective light reflection KW - LC composites Y1 - 2016 U6 - https://doi.org/10.1021/acsami.6b09642 SN - 1944-8244 VL - 8 SP - 27227 EP - 27235 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Fang, Liang A1 - Yan, Wan A1 - Nöchel, Ulrich A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Programming structural functions in phase-segregated polymers by implementing a defined thermomechanical history JF - Polymer : the international journal for the science and technology of polymers N2 - Unwanted shrinkage behaviors or failure in structural functions such as mechanical strength or deformability of polymeric products related to their thermomechanical history are a major challenge in production of plastics. Here, we address the question whether we can turn this challenge into an opportunity by creating defined thermomechanical histories in polymers, represented by a specific morphology and nanostructure, to equip polymeric shaped bodies with desired functions, e.g. a temperature-memory, by hot, warm or cold deformation into multiblock copolymers having two partially overlapping melting transitions. A copolyesterurethane named PDLCL, consisting of poly(epsilon-caprolactone) (PCL) and poly(omega-pentadecalactone) (PPDL) crystalline domains, exhibiting a pronounced phase-segregated morphology and partially overlapping melting transitions was selected for this study. Different types of PCL and PPDL crystals as well as distinct degrees of orientation in both amorphous and crystalline domains were obtained after deformation at 20 or 40 degrees C and to a lower extent at 60 degrees C. The generated non-isotropic structures were stable at ambient temperature and represent the different stresses stored. Stress-free heating experiments showed that the relaxation in both amorphous and crystalline phases occurred predominantly with melting of PCL crystals. When the switching temperature, which was similar to the applied deformation temperature (temperature-memory), was exceeded in stress-free heating experiments, the implemented thermomechanical history could be reversed. In contrast, during constant-strain heating to 60 degrees C the generated structural features remained almost unchanged. These findings provide insights about the structure function relation in multiblock copolymers with two crystalline phases exhibiting a temperature-memory effect by implementation of specific thermomechanical histories, which might be a general principle for tailoring other functions like mechanical strength or deformability in polymers. (C) 2016 Elsevier Ltd. All rights reserved. KW - Temperature-memory effect KW - Phase morphology KW - Thermomechanical history Y1 - 2016 U6 - https://doi.org/10.1016/j.polymer.2016.08.105 SN - 0032-3861 SN - 1873-2291 VL - 102 SP - 54 EP - 62 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Schöne, Anne-Christin A1 - Kratz, Karl A1 - Schulz, Burkhard A1 - Lendlein, Andreas T1 - The relevance of hydrophobic segments in multiblock copolyesterurethanes for their enzymatic degradation at the air-water interface JF - Polymer : the international journal for the science and technology of polymers N2 - The interplay of an enzyme with a multiblock copolymer PDLCL containing two segments of different hydrophilicity and degradability is explored in thin films at the air-water interface. The enzymatic degradation was studied in homogenous Langmuir monolayers, which are formed when containing more than 40 wt% oligo(epsilon-caprolactone) (OCL). Enzymatic degradation rates were significantly reduced with increasing content of hydrophobic oligo(omega-pentadecalactone) (OPDL). The apparent deceleration of the enzymatic process is caused by smaller portion of water-soluble degradation fragments formed from degradable OCL fragments. Beside the film degradation, a second competing process occurs after adding lipase from Pseudomonas cepacia into the subphase, namely the enrichment of the lipase molecules in the polymeric monolayer. The incorporation of the lipase into the Langmuir film is experimentally revealed by concurrent surface area enlargement and by Brewster angle microscopy (BAM). Aside from the ability to provide information about the degradation behavior of polymers, the Langmuir monolayer degradation (LMD) approach enables to investigate polymer-enzyme interactions for non-degradable polymers. (C) 2016 Elsevier Ltd. All rights reserved. KW - Multiblock copolymer KW - Enzymatic polymer degradation KW - Oligo(omega-pentadecalactone) KW - Oligo(epsilon-caprolactone) KW - Langmuir monolayer degradation technique Y1 - 2016 U6 - https://doi.org/10.1016/j.polymer.2016.09.001 SN - 0032-3861 SN - 1873-2291 VL - 102 SP - 92 EP - 98 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Weiler, Markus A1 - Menzel, Christoph A1 - Pertsch, Thomas A1 - Alaee, Rasoul A1 - Rockstuhl, Carsten A1 - Pacholski, Claudia T1 - Bottom-Up Fabrication of Hybrid Plasmonic Sensors: Gold-Capped Hydrogel Microspheres Embedded in Periodic Metal Hole Arrays JF - Polymer : the international journal for the science and technology of polymers N2 - The high potential of bottom-up fabrication strategies for realizing sophisticated optical sensors combining the high sensitivity of a surface plasmon resonance with the exceptional properties of stimuli-responsive hydrogel is demonstrated. The sensor is composed of a periodic hole array in a gold film whose holes are filled with gold-capped poly(N-isoproyl-acrylamide) (polyNIPAM) microspheres. The production of this sensor relies on a pure chemical approach enabling simple, time-efficient, and cost-efficient preparation of sensor platforms covering areas of cm(2). The transmission spectrum of this plasmonic sensor shows a strong interaction between propagating surface plasmon polaritons at the metal film surface and localized surface plasmon resonance of the gold cap on top of the polyNIPAM microspheres. Computer simulations support this experimental observation. These interactions lead to distinct changes in the transmission spectrum, which allow for the simultaneous, sensitive optical detection of refractive index changes in the surrounding medium and the swelling state of the embedded polyNIPAM microsphere under the gold cap. The volume of the polyNIPAM microsphere located underneath the gold cap can be changed by certain stimuli such as temperature, pH, ionic strength, and distinct molecules bound to the hydrogel matrix facilitating the detection of analytes which do not change the refractive index of the surrounding medium significantly. KW - bottom-up KW - hydrogel KW - hole array KW - sensor KW - surface plasmon resonance Y1 - 2016 U6 - https://doi.org/10.1021/acsami.6b08636 SN - 1944-8244 VL - 8 SP - 26392 EP - 26399 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Poghosyan, Armen H. A1 - Arsenyan, Levon H. A1 - Shahinyan, Aram A. A1 - Koetz, Joachim T1 - Polyethyleneimine loaded inverse SDS micelle in pentanol/toluene media JF - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects N2 - An atomic scale molecular dynamics simulation (100 ns) was carried out to reveal the conformational features of a cationic polyelectrolyte, i.e., hyperbranched polyethyleneimine (PEI), inside of water-in-oil microemulsion droplets stabilized by the anionic sodium dodecyl sulfate surfactant (SDS) layer. Simulations show that the polymer reorients very quickly and is localized at the headgroup region, i.e., the polymer nitrogens are close to SDS sulfur atoms. In spite of the availability of surface roughness caused by the polymer, we track a stable inverse micelle during the production run. In overall, the obtained parameters are well compared with experimental findings. (C) 2016 Elsevier B.V. All rights reserved. KW - SDS inverse micelle KW - Polyethyleneimine KW - Molecular dynamics simulations KW - Microemulsions Y1 - 2016 U6 - https://doi.org/10.1016/j.colsurfa.2016.07.018 SN - 0927-7757 SN - 1873-4359 VL - 506 SP - 402 EP - 408 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Zeng, Ting A1 - Frasca, Stefano A1 - Rumschöttel, Jens A1 - Koetz, Joachim A1 - Leimkühler, Silke A1 - Wollenberger, Ursula T1 - Role of Conductive Nanoparticles in the Direct Unmediated Bioelectrocatalysis of Immobilized Sulfite Oxidase JF - Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis KW - Direct electron transfer KW - Protein voltammetry KW - Human sulfite oxidase KW - Bioelectrocatalysis KW - Nanoparticles Y1 - 2016 U6 - https://doi.org/10.1002/elan.201600246 SN - 1040-0397 SN - 1521-4109 VL - 28 SP - 2303 EP - 2310 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Storch, Golo A1 - Maier, Frank A1 - Wessig, Pablo A1 - Trapp, Oliver T1 - Rotational Barriers of Substituted BIPHEP Ligands: A Comparative Experimental and Theoretical Study JF - European journal of organic chemistry N2 - The interconversion barriers of 14 different 3,3- and 5,5-disubstituted tropos BIPHEP [2,2-bis(diphenylphosphino)-1,1-biphenyl] and BIPHEP(O) [2,2-bis(diphenylphosphoryl)-1,1-biphenyl] ligands were investigated by enantioselective dynamic high performance liquid chromatography (DHPLC) and DFT calculations using the B3LYP/6-31G* and M06-2X/6-31G* levels of theory. The experimentally determined enantiomerization barriers varied from 86.8 to 101.4 kJmol(-1) and were found to be in excellent agreement with the calculated data. The root-mean-square deviations are 7.3 kJmol(-1) for the B3LYP functional and 11.3 kJmol(-1) for the M06-2X method. KW - Rotational barriers KW - Density functional calculations KW - Enantioselectivity KW - P ligands KW - Biaryls KW - Liquid chromatography Y1 - 2016 U6 - https://doi.org/10.1002/ejoc.201600836 SN - 1434-193X SN - 1099-0690 VL - 22 SP - 5123 EP - 5126 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wentrup, Curt A1 - Koch, Rainer A1 - Kleinpeter, Erich T1 - Twisted C=C Double Bonds with Very Low Rotational Barriers in Dioxanediones and Isoxazolones Determined by Low-Temperature Dynamic NMR Spectroscopy and Computational Chemistry JF - European journal of organic chemistry KW - NMR spectroscopy KW - Twisted double bonds KW - Push-pull effect KW - Density functional calculations Y1 - 2016 U6 - https://doi.org/10.1002/ejoc.201600931 SN - 1434-193X SN - 1099-0690 SP - 4985 EP - 4990 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Friedl, Christian A1 - Renger, Thomas A1 - Berlepsch, Hans V. A1 - Ludwig, Kai A1 - Schmidt am Busch, Marcel A1 - Megow, Jörg T1 - Structure Prediction of Self-Assembled Dye Aggregates from Cryogenic Transmission Electron Microscopy, Molecular Mechanics, and Theory of Optical Spectra JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - Cryogenic transmission electron microscopy (cryo-TEM) studies suggest that TTBC molecules self-assemble in aqueous solution to form single-walled tubes with a diameter of about 35 A. In order to reveal the arrangement and mutual orientations of the individual molecules in the tube, we combine information from crystal structure data of this dye with a calculation of linear absorbance and linear dichroism spectra and molecular dynamics simulations. We start with wrapping crystal planes in different directions to obtain tubes of suitable diameter. This set of tube models is evaluated by comparing the resulting optical spectra with experimental data. The tubes that can explain the spectra are investigated further by molecular dynamics simulations, including explicit solvent molecules. From the trajectories of the most stable tube models, the short-range ordering of the dye molecules is extracted and the optimization of the structure is iteratively completed. The final structural model is a tube of rings with 6-fold rotational symmetry, where neighboring rings are rotated by 30 and the-transition dipole moments of the chromophores form an angle of 74 with respect to the symmetry axis of the tube. This model is in agreement with cryo-TEM images and can explain the optical spectra, consisting of a sharp red-shifted J-band that is polarized parallel to to the symmetry axis of the tube and a broad blue-shifted H-band polarized perpendicular to this axis. The general structure of the homogeneous spectrum of this hybrid HJ-aggregate is described by an analytical model that explains the difference in redistribution of oscillator strength inside the vibrational manifolds of the J- and H-bands and the relative intensities and excitation energies of those bands. In addition to the-particular system investigated here, the present methodology can be expected to aid the structure prediction for a wide range of self-assembled dye aggregates. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpcc.6b05856 SN - 1932-7447 VL - 120 SP - 19416 EP - 19433 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Kovach, Ildiko A1 - Rumschöttel, Jens A1 - Friberg, Stig E. A1 - Koetz, Joachim T1 - Janus emulsion mediated porous scaffold bio-fabrication JF - Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces N2 - A three dimensional biopolymer network structure with incorporated nano-porous calcium phosphate (CaP) balls was fabricated by using gelatin-chitosan (GC) polymer blend and GC stabilized olive/silicone oil Janus emulsions, respectively. The emulsions were freeze-dried, and the oil droplets were washed out in order to prepare porous scaffolds with larger surface area. The morphology, pore size, chemical composition, thermal and swelling behavior was studied by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and micro-Differential Scanning Calorimetry (micro-DSC). Microscopic analysis confirmed that the pore size of the GC based sponges after freeze-drying may be drastically reduced by using Janus emulsions. Besides, the incorporation of nanoporous calcium phosphate balls is also lowering the pore size and enhancing thermal stability. (C) 2016 Elsevier B.V. All rights reserved. KW - Janus emulsions KW - Calcium phosphates KW - Gelatin-chitosan scaffolds Y1 - 2016 U6 - https://doi.org/10.1016/j.colsurfb.2016.05.018 SN - 0927-7765 SN - 1873-4367 VL - 145 SP - 347 EP - 352 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Wessig, Pablo A1 - Behrends, Nicole A1 - Kumke, Michael Uwe A1 - Eisold, Ursula T1 - FRET Pairs with Fixed Relative Orientation of Chromophores JF - European journal of organic chemistry N2 - Synthetic routes to different oligospirothioketal (OSTK) Forster resonance energy transfer (FRET) constructs are described and the photophysics of these constructs were explored in different solvents. The FRET efficiencies were determined from the experimental data and compared with theoretical values. The influence of the outstanding rigidity of the novel OSTK compounds on the FRET is discussed. KW - Fluorescence KW - Energy transfer KW - FRET KW - Chromophores KW - Spiro compounds Y1 - 2016 U6 - https://doi.org/10.1002/ejoc.201600489 SN - 1434-193X SN - 1099-0690 VL - 145 SP - 4476 EP - 4486 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schöne, Anne-Christin A1 - Kratz, Karl A1 - Schulz, Burkhard A1 - Lendlein, Andreas T1 - Polymer architecture versus chemical structure as adjusting tools for the enzymatic degradation of oligo(epsilon-caprolactone) based films at the air-water interface JF - Polymer Degradation and Stability N2 - The enzymatic degradation of oligo(epsilon-caprolactone) (OCL) based films at the air-water interface is investigated by Langmuir monolayer degradation (LMD) experiments to elucidate the influence of the molecular architecture and of the chemical structure on the chain scission process. For that purpose, the interactions of 2D monolayers of two star-shaped poly(epsilon-caprolactone)s (PCLs) and three linear OCL based copolyesterurethanes (P(OCL-U)) with the lipase from Pseudomonas cepacia are evaluated in comparison to linear OCL. While the architecture of star-shaped PCL Langmuir layers slightly influences their degradability compared to OCL films, significantly retarded degradations are observed for P(OCL-U) films containing urethane junction units derived from 2, 2 (4), 4-trimethyl hexamethylene diisocyanate (TMDI), hexamethylene diisocyanate (HDI) or lysine ethyl ester diisocyanate (LDI). The enzymatic degradation of the OCL based 2D structures is related to the presence of hydrophilic groups within the macromolecules rather than to the packing density of the film or to the molecular weight. The results reveal that the LMD technique allows the parallel analysis of both the film/enzyme interactions and the degradation process on the molecular level. (C) 2016 Elsevier Ltd. All rights reserved. KW - Langmuir technique KW - Oligo(epsilon-caprolactone) KW - Enzymatic degradation KW - Polymer architecture Y1 - 2016 U6 - https://doi.org/10.1016/j.polymdegradstab.2016.07.010 SN - 0141-3910 SN - 1873-2321 VL - 131 SP - 114 EP - 121 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Balci, K. A1 - Akkaya, Y. A1 - Akyuz, S. A1 - Collier, W. B. A1 - Stricker, M. C. A1 - Stover, D. D. A1 - Ritzhaupt, G. A1 - Koch, Andreas A1 - Kleinpeter, Erich T1 - The effects of conformation and zwitterionic tautomerism on the structural and vibrational spectral data of anserine JF - Vibrational spectroscopy : an international journal devoted to applications of infrared and raman spectroscopy N2 - In this study, the stable conformers of neutral anserine were searched by molecular dynamics simulations and energy minimization calculations using the MM2 force field. Thermochemical calculations at B3LYP/6-31G(d) level of theory followed these preliminary calculations. The results confirmed that neutral anserine has quite a flexible structure and many stable gauche and trans conformers at room temperature. Nevertheless, two are considerably more favourable in energy than the others and expected to dominate the gas-phase and matrix IR spectra of the molecule. The corresponding structural and vibrational spectral data for these two conformers of neutral anserine, whose relative stabilities were also examined by high-accuracy energy calculations carried out using G3MP2B3 method, and for the most stable conformer of anserine in zwitterion form were calculated at B3LYP/6-311++G(d,p) level of theory. The calculated harmonic force constants were refined using the Scaled Quantum Mechanical Force Field (SQM-FF) method and then used to produce the refined wavenumbers, potential energy distributions (PEDs) and IR and Raman intensities. These refined data together with the scaled harmonic wavenumbers obtained using another method, Dual Scale factors (DS), enabled us to correctly analyse the observed IR and Raman spectra of anserine and revealed the effects of conformation and zwitterionic tautomerism on its structural and vibrational spectral data. (C) 2016 Elsevier B.V. All rights reserved. KW - Anserine KW - Matrix IR spectrum KW - Tautomerism KW - SQM-FF KW - Dual scale factors Y1 - 2016 U6 - https://doi.org/10.1016/j.vibspec.2016.08.003 SN - 0924-2031 SN - 1873-3697 VL - 86 SP - 277 EP - 289 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Riebe, Daniel A1 - Eder, Alexander A1 - Ritschel, Thomas A1 - Beitz, Toralf A1 - Löhmannsröben, Hans-Gerd A1 - Beil, Andreas A1 - Blaschke, Michael A1 - Ludwig, Thomas T1 - Atmospheric pressure chemical ionization of explosives induced by soft X-radiation in ion mobility spectrometry: mass spectrometric investigation of the ionization reactions of drift gasses, dopants and alkyl nitrates JF - Journal of mass spectrometr N2 - A promising replacement for the radioactive sources commonly encountered in ion mobility spectrometers is a miniaturized, energy-efficient photoionization source that produce the reactant ions via soft X-radiation (2.8 keV). In order to successfully apply the photoionization source, it is imperative to know the spectrum of reactant ions and the subsequent ionization reactions leading to the detection of analytes. To that end, an ionization chamber based on the photoionization source that reproduces the ionization processes in the ion mobility spectrometer and facilitates efficient transfer of the product ions into a mass spectrometer was developed. Photoionization of pure gasses and gas mixtures containing air, N-2, CO2 and N2O and the dopant CH2Cl2 is discussed. The main product ions of photoionization are identified and compared with the spectrum of reactant ions formed by radioactive and corona discharge sources on the basis of literature data. The results suggest that photoionization by soft X-radiation in the negative mode is more selective than the other sources. In air, adduct ions of O-2 - with H2O and CO2 were exclusively detected. Traces of CO2 impact the formation of adduct ions of O-2 - and Cl -(upon addition of dopant) and are capable of suppressing them almost completely at high CO2 concentrations. Additionally, the ionization products of four alkyl nitrates (ethylene glycol dinitrate, nitroglycerin, erythritol tetranitrate and pentaerythritol tetranitrate) formed by atmospheric pressure chemical ionization induced by X-ray photoionization in different gasses (air, N-2 and N2O) and dopants (CH2Cl2, C2H5Br and CH3I) are investigated. The experimental studies are complemented by density functional theory calculations of the most important adduct ions of the alkyl nitrates (M) used for their spectrometric identification. In addition to the adduct ions [M + NO3](-) and [M + Cl](-), adduct ions such as [M + N2O2](-), [M + Br](-) and [M+ I](-) were detected, and their gas-phase structures and energetics are investigated by density functional theory calculations. Copyright (C) 2016 John Wiley & Sons, Ltd. KW - ion mobility spectrometry KW - mass spectrometry KW - explosives KW - X-ray KW - photoionization KW - alkyl nitrates Y1 - 2016 U6 - https://doi.org/10.1002/jms.3784 SN - 1076-5174 SN - 1096-9888 VL - 51 SP - 566 EP - 577 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Pape, Simon A1 - Wessig, Pablo A1 - Brunner, Heiko T1 - Iron Trichloride and Air Mediated Guanylation of Acylthioureas. An Ecological Route to Acylguanidines: Scope and Mechanistic Insights JF - The journal of organic chemistry N2 - Recently we introduced iron trichloride as an environmentally benign and cost-efficient reagent for the synthesis of N-benzoylguanidines. This highly attractive synthetic approach grants access to a broad spectrum of N-benzoylguanidines under mild conditions in short reaction times. In this work we present an extended scope of Our methodology along with the results obtained from mechanistic studies via in situ IR spectroscopy in combination with LC (liquid chromatography)-MS analyses. On the basis of these new mechanistic insights we were able to optimize the synthetic protocol and to develop an alternative mechanistic proposal. In this context the symbiotic roles of iron trithloride and oxygen in the guanylation process are highlighted. Y1 - 2016 U6 - https://doi.org/10.1021/acs.joc.6b00600 SN - 0022-3263 VL - 81 SP - 4701 EP - 4712 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schmidt, Bernd A1 - Wolf, Felix A1 - Ehlert, Christopher T1 - Systematic Investigation into the Matsuda-Heck Reaction of alpha-Methylene Lactones: How Conformational Constraints Direct the beta-H-Elimination Step JF - The journal of organic chemistry N2 - alpha-Methylene-gamma-butyrolactone and alpha-methylene-gamma-valerolactone undergo Pd-catalyzed Matsuda-Heck couplings with arene diazonium salts to alpha-benzyl butenolides or pentenolides, respectively, or to alpha-benzylidene lactones. The observed regioselectivity is strongly ring size dependent, with six-membered rings giving exclusively alpha-benzyl pentenolides, whereas the five-membered alpha-methylene lactone reacts to mixtures of regioisomers with a high proportion of (E)-alpha-benzylidene-gamma-butyrolactones. DFT calculations suggest that the reasons for these differences are not thermodynamic but kinetic in nature. The relative energies of the conformers of the Pd sigma-complexes resulting from insertion into the Pd-aryl bond were correlated with the dihedral angles between Pd and endo-beta-H. This correlation revealed that in the case of the six-membered lactone an energetically favorable conformer adopts a nearly synperiplanar Pd/endo-beta-H arrangement, whereas for the analogous Pd sigma-complex of the five-membered lactone the smallest Pd/endo-beta-H dihedral angle is observed for a conformer with a comparatively high potential energy. The optimized conditions for Matsuda-Heck arylations of exo-methylene lactones were eventually applied to the synthesis of the natural product anemarcoumarin A. Y1 - 2016 U6 - https://doi.org/10.1021/acs.joc.6b02207 SN - 0022-3263 VL - 81 SP - 11235 EP - 11249 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Oncak, Milan A1 - Wlodarczyk, Radoslaw A1 - Sauer, Joachim T1 - Hydration Structures of MgO, CaO, and SrO (001) Surfaces JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - Using density functional theory (PBE functional), we show that the degree of surface hydroxylation increases in the MgO, CaO, SrO series, accompanied by an increase in water adsorption energy. Already for water coverage of two monolayers, structures with dissolved M2+. ions are considerably more stable than the intact, nondissolved surface. The dissolved ions above the surface form different patterns including ordered ones (e.g., an infinite stripe) that are preferred for MgO(001) and CaO(001) and disordered ones that are favored for SrO(001). Contrary to previous assignments, an analysis of calculated X-ray photoelectron spectra shows that O(1s) signals arising from OH and H2O groups might coincide in the experimental spectrum. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpcc.6b07434 SN - 1932-7447 VL - 120 SP - 24762 EP - 24769 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Yan, Wan A1 - Fang, Liang A1 - Nöchel, Ulrich A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Influence of programming strain rates on the shape-memory performance of semicrystalline multiblock copolymers JF - Journal of polymer science : B, Polymer physics N2 - Multiblock copolymers named PCL-PIBMD consisting of crystallizable poly(epsilon-caprolactone) segments and crystallizable poly[oligo(3S-iso-butylmorpholine-2,5-dione)] segments coupled by trimethyl hexamethylene diisocyanate provide a versatile molecular architecture for achieving shape-memory effects (SMEs) in polymers. The mechanical properties as well as the SME performance of PCL-PIBMD can be tailored by the variation of physical parameters during programming such as deformation strain or applied temperature protocols. In this study, we explored the influence of applying different strain rates during programming on the resulting nanostructure of PCL-PIBMD. Programming was conducted at 50 degrees C by elongation to epsilon(m)=50% with strain rates of 1 or 10 or 50 mmmin(-1). The nanostructural changes were visualized by atomic force microscopy (AFM) measurements and investigated by in situ wide and small angle X-ray scattering experiments. With increasing the strain rate, a higher degree of orientation was observed in the amorphous domains. Simultaneously the strain-induced formation of new PIBMD crystals as well as the fragmentation of existing large PIBMD crystals occurred. The observed differences in shape fixity ratio and recovery stress of samples deformed with various strain rates can be attributed to their different nanostructures. The achieved findings can be relevant parameters for programming the shape-memory polymers with designed recovery forces. (c) 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1935-1943 KW - atomic force microscopy (AFM) KW - crystal structures KW - crystallization KW - multiblock copolymer KW - stimuli-sensitive polymers KW - SAXS KW - shape-memory effect KW - WAXS KW - X-ray scattering Y1 - 2016 U6 - https://doi.org/10.1002/polb.24097 SN - 0887-6266 SN - 1099-0488 VL - 54 SP - 1935 EP - 1943 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Zehbe, Rolf A1 - Zehbe, Kerstin T1 - Strontium doped poly-epsilon-caprolactone composite scaffolds made by reactive foaming JF - The European journal of the history of economic thought N2 - In the reconstruction and regeneration of bone tissue, a primary goal is to initiate bone growth and to stabilize the surrounding bone. In this regard, a potentially useful component in biomaterials for bone tissue engineering is strontium, which acts as cationic active agent, triggering certain intracellular pathways and acting as so called dual action bone agent which inhibits bone resorption while stimulating bone regeneration. In this study we established a novel processing for the foaming of a polymer (poly-epsilon-caprolactone) and simultaneous chemical reaction of a mixture of calcium and strontium hydroxides to the respective carbonates using supercritical carbon dioxide. The resultant porous composite scaffold was optimized in composition and strontium content and was characterized via different spectroscopic (infrared and Raman spectroscopy, energy dispersive X-ray spectroscopy), imaging (SEM, mu CT), mechanical testing and in vitro methods (fluorescence vital staining, MTT-assay). As a result, the composite scaffold showed good in vitro biocompatibility with partly open pore structure and the expected chemistry. First mechanical testing results indicate sufficient mechanical stability to support future in vivo applications. (C) 2016 Elsevier B.V. All rights reserved. KW - Strontium KW - Poly-epsilon-caprolactone KW - Porous scaffold KW - CAL-72 osteoblasts KW - L-929 fibroblasts KW - Reactive foaming KW - mu CT imaging KW - Spectroscopy Y1 - 2016 U6 - https://doi.org/10.1016/j.msec.2016.05.045 SN - 0928-4931 SN - 1873-0191 VL - 67 SP - 259 EP - 266 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Pavashe, Prashant A1 - Elamparuthi, Elangovan A1 - Hettrich, Cornelia A1 - Moeller, Heiko M. A1 - Linker, Torsten T1 - Synthesis of 2-Thiocarbohydrates and Their Binding to Concanavalin A JF - The journal of organic chemistry N2 - A convenient and general synthesis of 2-thiocarbohydrates via cerium ammonium nitrate oxidation of the thiocyanate ion is described. Radical addition to glycals proceeds with excellent regio- and good stereoselectivities in only one step, deprotection affords water-soluble 2-thio saccharides. Binding studies to Con A have been performed by isothermal titration calorimetry (ITC) and saturation transfer difference (STD) NMR spectroscopy. The 2-thiomannose derivative binds even stronger to Con A than the natural substrate, offering opportunities for new lectin or enzyme inhibitors. Y1 - 2016 U6 - https://doi.org/10.1021/acs.joc.6b00987 SN - 0022-3263 VL - 81 SP - 8595 EP - 8603 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Eisold, Ursula A1 - Behrends, Nicole A1 - Wessig, Pablo A1 - Kumke, Michael Uwe T1 - Rigid Rod-Based FRET Probes for Membrane Sensing Applications JF - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry N2 - Oligospirothioketal (OSTK) rods are presented as an adjustable scaffold for optical membrane probes. The OSTK rods are readily incorporated into lipid bilayers due to their hydrophobic backbones. Because of their high length-over-diameter aspect ratio, only a minimal disturbance of the lipid bilayer is caused. OSTK rods show outstanding rigidity and allow defined labeling with fluorescent dyes, yielding full control of the orientation between the dye and OSTK skeleton. This. allows the construction of novel Forster resonance energy transfer probes with highly defined relative orientations of the transition dipole moments of the donor and acceptor dyes and makes the class of OSTK probes a power-fill, flexible toolbox for optical biosensing applications. Data on steady-state and time-resolved fluorescence experiments investigating the incorporation of coumarin- and [1,3]-dioxolo[4,5-f][1,3]benzo-dioxole-labeled OSTKs in large unilamellar vesicles are presented as a show case. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpcb.6b07285 SN - 1520-6106 VL - 120 SP - 9935 EP - 9943 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Megow, Jörg T1 - Computing dispersive, polarizable, and electrostatic shifts of excitation energy in supramolecular systems: PTCDI crystal JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - The gas-to-crystal-shift denotes the shift of electronic excitation energies, i.e., the difference between ground and excited state energies, for a molecule transferred from the gas to the bulk phase. The contributions to the gas-to-crystal-shift comprise electrostatic as well as inductive polarization and dispersive energy shifts of the molecular excitation energies due to interaction with environmental molecules. For the example of 3,4,9,10-perylene-tetracarboxylic-diimide (PTCDI) bulk, the contributions to the gas-to-crystal shift are investigated. In the present work, electrostatic interaction is calculated via Coulomb interaction of partial charges while inductive and dispersive interactions are obtained using respective sum over states expressions. The coupling of higher transition densities for the first 4500 excited states of PTCDI was computed using transition partial charges based on an atomistic model of PTCDI bulk obtained from molecular dynamics simulations. As a result it is concluded that for the investigated model system of a PTCDI crystal, the gas to crystal shift is dominated by dispersive interaction. Published by AIP Publishing. Y1 - 2016 U6 - https://doi.org/10.1063/1.4962179 SN - 0021-9606 SN - 1089-7690 VL - 145 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Bauch, Marcel A1 - Böttcher, Dominique A1 - Bornscheuer, Uwe T. A1 - Linker, Torsten T1 - Enzymatic Cleavage of Aryl Acetates JF - ChemCatChem : heterogeneous & homogeneous & bio- & nano-catalysis ; a journal of ChemPubSoc Europe N2 - Seven enzymes have been screened for the cleavage of aryl acetates. Phenyl and naphthyl acetates react with lipases and esterases, whereas the sterically demanding anthracene acetate gave a conversion only with porcine liver esterase and esterase 2 from Bacillus subtilis (BS2). These two enzymes have been employed on a preparative (0.5 mmol) scale and afforded cleavage products in 91 and 94% yields, even for anthracene acetate. Thus, this method is superior to chemical cleavage with catalytic amounts of sodium methoxide (Zemplen conditions), which gave only low conversions. Finally, regioselectivity has been achieved with an anthracene bisacetate, in which an ethyl group controls the cleavage of the first acetate. This indicates that steric interactions play a crucial role in the enzymatic cleavage of aryl acetates, which might be interesting for future applications or the development of enzyme inhibitors. KW - arenes KW - enzyme catalysis KW - regioselectivity KW - steric hindrance KW - substituent effects Y1 - 2016 U6 - https://doi.org/10.1002/cctc.201600678 SN - 1867-3880 SN - 1867-3899 VL - 8 SP - 2853 EP - 2857 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schulze, Nicole A1 - Prietzel, Claudia Christina A1 - Koetz, Joachim T1 - Polyampholyte-mediated synthesis of anisotropic gold nanoplatelets JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - This paper focused on the synthesis of triangular nanoplatelets in the presence of a tubular network structure. The tubular network structure is formed by adding a strongly alternating polyampholyte, i.e., PalPhBisCarb, to a mixed vesicle system with a negatively charged bilayer containing phosphatidylcholin and AOT. Using the tubular network as a reducing agent in a one-step procedure, triangular and hexagonal nanoplatelets are formed. One can show that the nanoplatelet yield is enhanced by increasing the temperature and decreasing the reaction time. The platelet edge length can be decreased by heating the system up to 100 A degrees C. Due to specific interactions between PalPhBisCarb and the AOT/phospholipid bilayer, stacking and welding effects lead to the formation of ordered platelet structures. The reaction pathway to flat gold nanotriangles is discussed with regard to the twin plane growth model of gold nanoplates. KW - Polyampholytes KW - Tubular network structure KW - Anisotropic gold nanoplatelets KW - Nanocrystal growth KW - Nanotriangle stacking and welding Y1 - 2016 U6 - https://doi.org/10.1007/s00396-016-3890-y SN - 0303-402X SN - 1435-1536 VL - 294 SP - 1297 EP - 1304 PB - Springer CY - New York ER - TY - JOUR A1 - Rasovic, Aleksandar A1 - Blagojevic, Vladimir A1 - Baranac-Stojanovic, Marija A1 - Kleinpeter, Erich A1 - Markovic, Rade A1 - Minic, Dragica M. T1 - Quantification of the push-pull effect in 2-alkylidene-4-oxothiazolidines by using NMR spectral data and barriers to rotation around the C=C bond JF - New journal of chemistry N2 - Information about the strength of donor-acceptor interactions in push-pull alkenes is valuable, as this so-called "push-pull effect' influences their chemical reactivity and dynamic behaviour. In this paper, we discuss the applicability of NMR spectral data and barriers to rotation around the CQC double bond to quantify the push-pull effect in biologically important 2-alkylidene-4-oxothiazolidines. While olefinic proton chemical shifts and differences in C-13 NMR chemical shifts of the two carbons constituting the CQC double bond fail to give the correct trend in the electron withdrawing ability of the substituents attached to the exocyclic carbon of the double bond, barriers to rotation prove to be a reliable quantity in providing information about the extent of donor-acceptor interactions in the push-pull systems studied. In particular all relevant kinetic data, that is the Arrhenius parameters ( apparent activation energy Ea and frequency factor A) and activation parameters ( Delta S-double dagger, Delta H-double dagger and Delta G(double dagger)), were determined from the data of the experimentally studied configurational isomerization of ( E)-9a. These results were compared to previously published related data for other two compounds, ( Z)-1b and ( 2E, 5Z)-7, showing that experimentally determined Delta G(double dagger) values are a good indicator of the strength of push-pull character. Theoretical calculations of the rotational barriers of eight selected derivatives excellently correlate with the calculated CQC bond lengths and corroborate the applicability of Delta G(double dagger) for estimation of the strength of the push-pull effect in these and related systems. Y1 - 2016 U6 - https://doi.org/10.1039/c6nj00901h SN - 1144-0546 SN - 1369-9261 VL - 40 SP - 6364 EP - 6373 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schneider, Rudolf A1 - Weigert, F. A1 - Lesnyak, V. A1 - Leubner, S. A1 - Lorenz, T. A1 - Behnke, Thomas A1 - Dubavik, A. A1 - Joswig, J. -O. A1 - Resch-Genger, U. A1 - Gaponik, N. A1 - Eychmueller, A. T1 - pH and concentration dependence of the optical properties of thiol-capped CdTe nanocrystals in water and D2O JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - The optical properties of semiconductor nanocrystals (SC NCs) are largely controlled by their size and surface chemistry, i.e., the chemical composition and thickness of inorganic passivation shells and the chemical nature and number of surface ligands as well as the strength of their bonds to surface atoms. The latter is particularly important for CdTe NCs, which – together with alloyed CdxHg1−xTe – are the only SC NCs that can be prepared in water in high quality without the need for an additional inorganic passivation shell. Aiming at a better understanding of the role of stabilizing ligands for the control of the application-relevant fluorescence features of SC NCs, we assessed the influence of two of the most commonly used monodentate thiol ligands, thioglycolic acid (TGA) and mercaptopropionic acid (MPA), on the colloidal stability, photoluminescence (PL) quantum yield (QY), and PL decay behavior of a set of CdTe NC colloids. As an indirect measure for the strength of the coordinative bond of the ligands to SC NC surface atoms, the influence of the pH (pD) and the concentration on the PL properties of these colloids was examined in water and D2O and compared to the results from previous dilution studies with a set of thiol-capped Cd1−xHgxTe SC NCs in D2O. As a prerequisite for these studies, the number of surface ligands was determined photometrically at different steps of purification after SC NC synthesis with Ellman's test. Our results demonstrate ligand control of the pH-dependent PL of these SC NCs, with MPA-stabilized CdTe NCs being less prone to luminescence quenching than TGA-capped ones. For both types of CdTe colloids, ligand desorption is more pronounced in H2O compared to D2O, underlining also the role of hydrogen bonding and solvent molecules. Y1 - 2016 U6 - https://doi.org/10.1039/c6cp03123d SN - 1463-9076 SN - 1463-9084 VL - 18 SP - 19083 EP - 19092 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Fallah, Mohammad A. A1 - Stanglmair, Christoph A1 - Pacholski, Claudia A1 - Hauser, Karin T1 - Devising Self-Assembled-Monolayers for Surface-Enhanced Infrared Spectroscopy of pH-Driven Poly-L-lysine Conformational Changes JF - Langmuir N2 - Surface-enhanced infrared absorption spectroscopy (SEIRA) is applied to study protein conformational changes. In general, the appropriate functionalization of metal surfaces with biomolecules remains a challenge if the conformation and activity of the biomolecule shall be preserved. Here we present a SEIRA study to monitor pH-induced conformational changes of poly-L lysine (PLL) covalently bound to a thin gold layer via self assembled monolayers (SAMs). We demonstrate that the composition of the SAM is crucial. A SAM of 11-mercaptoundecanonic acid (MUA) can link PLL to the gold layer, but pH-driven conformational transitions were hindered compared to poly-L lysine in solution. To address this problem, we devised a variety of SAMs, i.e., mixed SAMs of MUA with either octanethiol (OT) or 11-mercapto-1-undecanol (MUoL) and furthermore SAMs of MT(PEG)(4) and NHS-PEG(10k)-SH. These mixed SAMs modify the surface properties by changing the polarity and the morphology of the surface present to nearby PLL molecules. Our experiments reveal that mixed SAMs of MUA-MUoL and SAMs of NHS-PEG(10k)-SH-MT(PEG)(4) are suitable to monitor pH-driven conformational changes of immobilized PLL. These SAMs might be applicable for chemoselective protein immobilization in general. Y1 - 2016 U6 - https://doi.org/10.1021/acs.langmuir.6b01742 SN - 0743-7463 VL - 32 SP - 7356 EP - 7364 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Draffehn, Soeren A1 - Eichhorst, Jenny A1 - Wiesner, Burkhard A1 - Kumke, Michael Uwe T1 - Insight into the Modification of Polymeric Micellar and Liposomal Nanocarriers by Fluorescein-Labeled Lipids and Uptake-Mediating Lipopeptides JF - Langmuir N2 - Encapsulation of diagnostic and therapeutic compounds in transporters improves their delivery to the point of need. An even more efficient treatment of diseases can be achieved using carriers with targeting or protecting moieties. In the present work, we investigated micellar and liposomal nanocarriers modified with fluorescein, peptides, and polymers that are covalently bound to fatty acids or phospholipids to ensure a self-driven incorporation into the micelles or liposomes. First, we characterized the photophysics of the fluorescent probes in the absence and in the presence of nanocarriers. Changes in the fluorescence decay time, quantum yield, and intensity of a fluorescein-labeled fatty acid (fluorescein-labeled palmitic acid [fPA]) and a fluorescein-labeled lipopeptide (P2fA2) were found. By exploiting these changes, we investigated a lipopeptide (P2A2 as an uptake-mediating unit) in combination with different nanocarriers (micelles and liposomes) and determined the corresponding association constant K-ass values, which were found to be very high. In addition, the mobility of fPA was exploited using fluorescence correlation spectroscopy (FCS) and fluorescence depolarization (FD) experiments to characterize the nanocarriers. Cellular uptake experiments with mouse brain endothelial cells provided information on the uptake behavior of liposomes modified by uptake-mediating P2A2 and revealed differences in the uptake behavior between pH-sensitive and pH-insensitive liposomes. Y1 - 2016 U6 - https://doi.org/10.1021/acs.langmuir.6b01487 SN - 0743-7463 VL - 32 SP - 6928 EP - 6939 PB - American Chemical Society CY - Heidelberg ER - TY - JOUR A1 - Wong, Joseph K. -H. A1 - Ast, Sandra A1 - Yu, Mingfeng A1 - Flehr, Roman A1 - Counsell, Andrew J. A1 - Turner, Peter A1 - Crisologo, Patrick A1 - Todd, Matthew H. A1 - Rutledge, Peter J. T1 - Synthesis and Evaluation of 1,8-Disubstituted-Cyclam/Naphthalimide Conjugates as Probes for Metal Ions JF - ChemistryOpen : including thesis treasury N2 - Fluorescent molecular probes for metal ions have a raft of potential applications in chemistry and biomedicine. We report the synthesis and photophysical characterisation of 1,8-disubstituted-cyclam/naphthalimide conjugates and their zinc complexes. An efficient synthesis of 1,8-bis-(2-azidoethyl)cyclam has been developed and used to prepare 1,8-disubstituted triazolyl-cyclam systems, in which the pendant group is connected to triazole C4. UV/Vis and fluorescence emission spectra, zinc binding experiments, fluorescence quantum yield and lifetime measurements and pH titrations of the resultant bis-naphthalimide ligand elucidate a complex pattern of photophysical behaviour. Important differences arise from the inclusion of two fluorophores in the one probe and from the variation of triazole substitution pattern (dye at C4 vs. N1). Introducing a second fluorophore greatly extends fluorescence lifetimes, whereas the altered substitution pattern at the cyclam amines exerts a major influence on fluorescence output and metal binding. Crystal structures of two key zinc complexes evidence variations in triazole coordination that mirror the solution-phase behaviour of these systems. KW - chromophores KW - click triazoles KW - fluorescent probes KW - macrocyclic compounds KW - photophysics Y1 - 2016 U6 - https://doi.org/10.1002/open.201600010 SN - 2191-1363 VL - 5 SP - 375 EP - 385 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Paramonov, Guennaddi K. A1 - Kuehn, O. A1 - Bandrauk, Andre D. T1 - Shaped Post-Field Electronic Oscillations in H-2(+) Excited by Two-Cycle Laser Pulses: Three-Dimensional Non-Born-Oppenheimer Simulations JF - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory N2 - Quantum dynamics of H-2(+) excited by two-cycle laser pulses with laser carrier frequencies corresponding to the wavelengths lambda(1) = 800 and 200 nm (corresponding to the periods tau(1) = 2.667 and 0.667 fs, respectively) and being linearly polarized along the molecular axis have been studied by the numerical solution of the non-Born-Oppenheimer time-dependent Schrodinger equation within a three-dimensional (3D) model, including the internuclear distance R and electron coordinates z and rho. The amplitudes of the pulses have been chosen such that the energies of H-2(+) after the ends of the laser pulses, < E > approximate to-0.515 au, were close to the dissociation threshold of H-2(+). It is found that there exists a certain characteristic oscillation frequency omega(osc) = 0.2278 au (corresponding to the period tau(osc) = 0.667 fs and the wavelength lambda(osc) = 200 nm) that plays the role of a "carrier" frequency of temporally shaped oscillations of the expectation values <-partial derivative V/partial derivative z) emerging after the ends of the laser pulses, both at lambda(1) = 800 nm and at lambda(1) = 200 nm. Moreover, at lambda(1) = 200 nm, the expectation value < z > also demonstrates temporally shaped oscillations after the end of the laser pulse. In contrast, at lambda(1) = 800 nm, the characteristic oscillation frequency omega(osc) = 0.2278 au appears as the frequency of small-amplitude oscillations of the slowly varying expectation value < z > which makes, after the end of the pulse, an excursion with an amplitude of about 4.5 au along the z axis and returns back to < z > approximate to 0 afterward. It is found that the period of the temporally shaped post-field oscillations of <-partial derivative V/partial derivative z > and < z >, estimated as tau(shp) approximate to 30 fs, correlates with the nuclear motion. It is also shown that vibrational excitation of H-2(+) is accompanied by the formation of "hot" and "cold" vibrational ensembles along the R degree of freedom. Power spectra related to the electron motion in H-2(+) calculated for both the laser-driven z and optically passive rho degrees of freedom in the acceleration form proved to be very interesting. In particular, both odd and even harmonics can be observed. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpca.5b11599 SN - 1089-5639 VL - 120 SP - 3175 EP - 3185 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Soliveres, Santiago A1 - Manning, Peter A1 - Prati, Daniel A1 - Gossner, Martin M. A1 - Alt, Fabian A1 - Arndt, Hartmut A1 - Baumgartner, Vanessa A1 - Binkenstein, Julia A1 - Birkhofer, Klaus A1 - Blaser, Stefan A1 - Bluethgen, Nico A1 - Boch, Steffen A1 - Boehm, Stefan A1 - Boerschig, Carmen A1 - Buscot, Francois A1 - Diekoetter, Tim A1 - Heinze, Johannes A1 - Hoelzel, Norbert A1 - Jung, Kirsten A1 - Klaus, Valentin H. A1 - Klein, Alexandra-Maria A1 - Kleinebecker, Till A1 - Klemmer, Sandra A1 - Krauss, Jochen A1 - Lange, Markus A1 - Morris, E. Kathryn A1 - Mueller, Joerg A1 - Oelmann, Yvonne A1 - Overmann, Jörg A1 - Pasalic, Esther A1 - Renner, Swen C. A1 - Rillig, Matthias C. A1 - Schaefer, H. Martin A1 - Schloter, Michael A1 - Schmitt, Barbara A1 - Schoening, Ingo A1 - Schrumpf, Marion A1 - Sikorski, Johannes A1 - Socher, Stephanie A. A1 - Solly, Emily F. A1 - Sonnemann, Ilja A1 - Sorkau, Elisabeth A1 - Steckel, Juliane A1 - Steffan-Dewenter, Ingolf A1 - Stempfhuber, Barbara A1 - Tschapka, Marco A1 - Tuerke, Manfred A1 - Venter, Paul A1 - Weiner, Christiane N. A1 - Weisser, Wolfgang W. A1 - Werner, Michael A1 - Westphal, Catrin A1 - Wilcke, Wolfgang A1 - Wolters, Volkmar A1 - Wubet, Tesfaye A1 - Wurst, Susanne A1 - Fischer, Markus A1 - Allan, Eric T1 - Locally rare species influence grassland ecosystem multifunctionality JF - Philosophical transactions of the Royal Society of London : B, Biological sciences N2 - Species diversity promotes the delivery of multiple ecosystem functions (multifunctionality). However, the relative functional importance of rare and common species in driving the biodiversity multifunctionality relationship remains unknown. We studied the relationship between the diversity of rare and common species (according to their local abundances and across nine different trophic groups), and multifunctionality indices derived from 14 ecosystem functions on 150 grasslands across a land use intensity (LUI) gradient. The diversity of above- and below-ground rare species had opposite effects, with rare above-ground species being associated with high levels of multifunctionality, probably because their effects on different functions did not trade off against each other. Conversely, common species were only related to average, not high, levels of multifunctionality, and their functional effects declined with LUI. Apart from the community level effects of diversity, we found significant positive associations between the abundance of individual species and multifunctionality in 6% of the species tested. Species specific functional effects were best predicted by their response to LUI: species that declined in abundance with land use intensification were those associated with higher levels of multifunctionality. Our results highlight the importance of rare species for ecosystem multifunctionality and help guiding future conservation priorities. KW - biodiversity KW - common species KW - ecosystem function KW - identity hypothesis KW - land use KW - multitrophic Y1 - 2016 U6 - https://doi.org/10.1098/rstb.2015.0269 SN - 0962-8436 SN - 1471-2970 VL - 371 SP - 3175 EP - 3185 PB - Royal Society CY - London ER - TY - JOUR A1 - Sun, Haitao A1 - Ryno, Sean A1 - Zhong, Cheng A1 - Ravva, Mahesh Kumar A1 - Sun, Zhenrong A1 - Körzdörfer, Thomas A1 - Bredas, Jean-Luc T1 - Ionization Energies, Electron Affinities, and Polarization Energies of Organic Molecular Crystals: Quantitative Estimations from a Polarizable Continuum Model (PCM)-Tuned Range-Separated Density Functional Approach JF - Journal of chemical theory and computation N2 - We propose a new methodology for the first principles description of the electronic properties relevant for charge transport in organic molecular crystals. This methodology, which is based on the combination of a nonempirical, optimally tuned range separated hybrid functional with the polarizable continuum model, is applied to a series of eight representative molecular semiconductor crystals. We show that it provides ionization energies, electron affinities, and transport gaps in very good agreement with experimental values, as well as with the results of many-body perturbation theory-within the GW approximation at a fraction of the computational cost. Hence, this approach represents an easily applicable and computationally efficient tool to estimate the gas-to crystal phase shifts of the frontier-orbital quasiparticle energies in organic electronic materials. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.6b00225 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 2906 EP - 2916 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Dzhigaev, D. A1 - Shabalin, A. A1 - Stankevic, T. A1 - Lorenz, Ulf A1 - Kurta, R. P. A1 - Seiboth, F. A1 - Wallentin, J. A1 - Singer, A. A1 - Lazarev, S. A1 - Yefanov, O. M. A1 - Borgstrom, M. A1 - Strikhanov, M. N. A1 - Samuelson, L. A1 - Falkenberg, G. A1 - Schroer, C. G. A1 - Mikkelsen, A. A1 - Vartanyants, I. A. T1 - Bragg coherent x-ray diffractive imaging of a single indium phosphide nanowire JF - Journal of optics N2 - Three-dimensional (3D) Bragg coherent x-ray diffractive imaging (CXDI) with a nanofocused beam was applied to quantitatively map the internal strain field of a single indium phosphide nanowire. The quantitative values of the strain were obtained by pre-characterization of the beam profile with transmission ptychography on a test sample. Our measurements revealed the 3D strain distribution in a region of 150 nm below the catalyst Au particle. We observed a slight gradient of the strain in the range of +/- 0.6% along the [111] growth direction of the nanowire. We also determined the spatial resolution in our measurements to be about 10 nm in the direction perpendicular to the facets of the nanowire. The CXDI measurements were compared with the finite element method simulations and show a good agreement with our experimental results. The proposed approach can become an effective tool for in operando studies of the nanowires. KW - Bragg coherent x-ray diffractive imaging KW - InP nanowires KW - strain field Y1 - 2016 U6 - https://doi.org/10.1088/2040-8978/18/6/064007 SN - 2040-8978 SN - 2040-8986 VL - 18 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Steeples, Elliot A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Esposito, Davide T1 - Amino acid-derived N-heterocyclic carbene palladium complexes for aqueous phase Suzuki-Miyaura couplings JF - New journal of chemistry N2 - In this work, three ligands produced from amino acids were synthesized and used to produce five bis- and PEPPSI-type palladium-NHC complexes using a novel synthesis route from sustainable starting materials. Three of these complexes were used as precatalysts in the aqueous-phase Suzuki-Miyaura coupling of various substrates displaying high activity. TEM and mercury poisoning experiments provide evidence for Pd-nanoparticle formation stabilized in water. Y1 - 2016 U6 - https://doi.org/10.1039/c5nj03337c SN - 1144-0546 SN - 1369-9261 VL - 40 SP - 4922 EP - 4930 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Schmidt, Bernd A1 - Wolf, Felix A1 - Brunner, Heiko T1 - Styrylsulfonates and -Sulfonamides through Pd-Catalysed Matsuda-Heck Reactions of Vinylsulfonic Acid Derivatives and Arenediazonium Salts JF - European journal of organic chemistry N2 - Arene diazonium salts undergo Matsuda-Heck reactions with vinylsulfonates and -sulfonamides to give styrylsulfonic acid derivatives in high to excellent yields and with high to excellent selectivities. By quantifying the evolution of nitrogen over time in a gas-meter apparatus, the reactivities of ethylvinylsulfonate and the benchmark olefin methyl acrylate were compared for an electron-rich and an -deficient arene diazonium salt. Tertiary sulfonamides react in Matsuda-Heck couplings with high conversions, but require long reaction times, which prevents the determination of kinetic data through the measurement of nitrogen evolution. Secondary sulfonamides were found to be unreactive. From these results, the following order of reactivity could be deduced: H2C=CHCO2Me > H2C=CHSO2OEt > H2C=CHSO2N(Me)Bn >> H2C=CHSO2NHBn. Through the Matsuda-Heck coupling of 5-indolyldiazonium salt and a tertiary vinylsulfonamide, the synthesis of the C-5-substituted indole part of the antimigraine drug naratriptan was accomplished in high yield. KW - Homogeneous catalysis KW - Cross-coupling KW - Palladium KW - Sulfonamides KW - Alkenes KW - Drug design Y1 - 2016 U6 - https://doi.org/10.1002/ejoc.201600469 SN - 1434-193X SN - 1099-0690 SP - 2972 EP - 2982 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Draffehn, Soeren A1 - Kumke, Michael Uwe T1 - Monitoring the Collapse of pH-Sensitive Liposomal Nanocarriers and Environmental pH Simultaneously: A Fluorescence-Based Approach JF - Molecular pharmaceutics N2 - Nowadays, the encapsulation of therapeutic compounds in so-called carrier systems is a very smart method to achieve protection as well as an improvement of their temporal and spatial distribution. After the successful transport to the point of care, the delivery has to be released under controlled conditions. To monitor the triggered release from the carrier, we investigated different fluorescent probes regarding their response to the pH-induced collapse of pH-sensitive liposomes (pHSLip), which occurs when the environmental pH falls below a critical value. Depending on the probe, the fluorescence decay time as well as fluorescence anisotropy can be used equally as key parameters for monitoring the collapse. Especially the application of a fluorescein labeled fatty acid (fPA) enabled the monitoring of the pHSLips collapse and the pH of its microenvironment simultaneously without interference. Varying the pH in the range of 3 < pH < 9, anisotropy data revealed the critical pH value at which the collapse of the pHSLips occurs. Complementary methods, e.g., fluorescence correlation spectroscopy and dynamic light scattering, supported the analysis based on the decay time and anisotropy. Additional experiments with varying incubation times yielded information on the kinetics of the liposomal collapse. KW - pH-sensitive liposome KW - drug carrier system KW - selective drug release KW - intracellular pH indicator KW - time-resolved fluorescence spectroscopy KW - fluorescence anisotropy KW - fluorescence correlation spectroscopy Y1 - 2016 U6 - https://doi.org/10.1021/acs.molpharmaceut.5b00064 SN - 1543-8384 VL - 13 SP - 1608 EP - 1617 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Bois, Juliana A1 - Körzdörfer, Thomas T1 - 0 How Bond Length Alternation and Thermal Disorder Affect the Optical Excitation Energies of pi-Conjugated Chains: A Combined Density Functional Theory and Molecular Dynamics Study JF - Journal of chemical theory and computation N2 - We dissect the sources of error leading to inaccuracies in the description of the geometry and optical excitation energies of pi-conjugated polymers. While the ground-state bond length alternation is shown to be badly reproduced by standard functionals, the recently adapted functionals PBEh* and omega PBE* as well as the double hybrid functional XYGJ-OS manage to replicate results obtained at the CCSD(T) level. By analysis of the bond length alternation in the excited state, a sensitive dependence of the exciton localization on the long-range behavior of the functional and the amount of Hartree-Fock exchange present is shown. Introducing thermal disorder through molecular dynamics simulations allows the consideration of a range of thermally accessible configurations of each oligomer, including trans to cis rotations, which break the conjugation of the backbone. Thermal disorder has a considerable effect when combined with functionals that overestimate the delocalization of the excitation, such as B3LYP. For functionals with a larger amount of exact exchange such as our PBEh* and omega PBE*, however, the effect is small, as excitations are often localized enough to fit between twists in the chain. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.5b01070 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 1872 EP - 1882 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Pinyou, Piyanut A1 - Ruff, Adrian A1 - Poeller, Sascha A1 - Barwe, Stefan A1 - Nebel, Michaela A1 - Alburquerque, Natalia Guerrero A1 - Wischerhoff, Erik A1 - Laschewsky, Andre A1 - Schmaderer, Sebastian A1 - Szeponik, Jan A1 - Plumere, Nicolas A1 - Schuhmann, Wolfgang T1 - Thermoresponsive amperometric glucose biosensor JF - Biointerphases N2 - The authors report on the fabrication of a thermoresponsive biosensor for the amperometric detection of glucose. Screen printed electrodes with heatable gold working electrodes were modified by a thermoresponsive statistical copolymer [polymer I: poly(omega-ethoxytriethylenglycol methacrylate-omega-3-(N,N-dimethyl-N-2-methacryloyloxyethyl ammonio) propanesulfonate-co-omega-butoxydiethylenglycol methacrylate-co-2-(4-benzoyl-phenoxy)ethyl methacrylate)] with a lower critical solution temperature of around 28 degrees C in aqueous solution via electrochemically induced codeposition with a pH-responsive redox-polymer [polymer II: poly(glycidyl methacrylate-co-allyl methacrylate-co-poly(ethylene glycol) methacrylate-co-butyl acrylate-co-2-(dimethylamino) ethyl methacrylate)-[Os(bpy)(2)(4-(((2-(2-(2-aminoethoxy) ethoxy) ethyl) amino) methyl)-N,N-dimethylpicolinamide)](2+)] and pyrroloquinoline quinone-soluble glucose dehydrogenase acting as biological recognition element. Polymer II bears covalently bound Os-complexes that act as redox mediators for shuttling electrons between the enzyme and the electrode surface. Polymer I acts as a temperature triggered immobilization matrix. Probing the catalytic current as a function of the working electrode temperature shows that the activity of the biosensor is dramatically reduced above the phase transition temperature of polymer I. Thus, the local modulation of the temperature at the interphase between the electrode and the bioactive layer allows switching the biosensor from an on-to an off-state without heating of the surrounding analyte solution. (C) 2015 American Vacuum Society. Y1 - 2016 U6 - https://doi.org/10.1116/1.4938382 SN - 1934-8630 SN - 1559-4106 VL - 11 PB - American Institute of Physics CY - Melville 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 - Kovach, Ildiko A1 - Won, Jooyoung A1 - Friberg, Stig E. A1 - Koetz, Joachim T1 - Completely engulfed olive/silicone oil Janus emulsions with gelatin and chitosan JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - Janus emulsions, formed by mixing two oil components (i.e., olive oil (OO) and silicone oil (SiO)) with water in the presence of two surface active biopolymers, i.e., gelatin and chitosan, are investigated in more detail. The stability of Janus droplets formed strongly depends on the polymer components used. The mixture of both biopolymers represents an extraordinary effect which can be related to the complex formation of gelatin and chitosan. Taken into account that under the given pH conditions, in the acidic pH range between 4 and 6, below the isoelectric point of gelatin, both polymers are polycations, one can conclude that non-Coulombic interactions are of relevance for the enhanced surface activity of the complexes. Dynamic interfacial tension (gamma) measurements by using the drop profile analysis tensiometry (PAT) indicate a strong adsorption of the polymer complexes at the olive oil/water interface in contrast to the silicone/water interface. In a first step, the polymer complexes are adsorbed at the interface, and in a second step, a more rigid skin-like polymer layer is formed. This first example of a polymer-stabilized Janus emulsion opens new perspectives for the application, e.g., in food emulsions or for making scaffold materials. KW - Janus emulsions KW - Interfacial tension KW - Ring method KW - Drop profile analysis tensiometry KW - Gelatin-chitosan composites Y1 - 2016 U6 - https://doi.org/10.1007/s00396-016-3828-4 SN - 0303-402X SN - 1435-1536 VL - 294 SP - 705 EP - 713 PB - Springer CY - New York ER - TY - JOUR A1 - Zabel, Andre A1 - Winter, Alette A1 - Kelling, Alexandra A1 - Schilde, Uwe A1 - Strauch, Peter T1 - Tetrabromidocuprates(II)-Synthesis, Structure and EPR JF - International journal of molecular sciences N2 - Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several "onium" cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and g(perpendicular to)) of the tensors could be determined and information on the structural changes in the [CuBr4](2-) anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. KW - tetrabromidocuprate(II) KW - X-ray structure KW - electron paramagnetic resonance KW - copper(II) Y1 - 2016 U6 - https://doi.org/10.3390/ijms17040596 SN - 1422-0067 VL - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Gallandi, Lukas A1 - Marom, Noa A1 - Rinke, Patrick A1 - Körzdörfer, Thomas T1 - Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules II: Non-Empirically Tuned Long-Range Corrected Hybrid Functionals JF - Journal of chemical theory and computation N2 - The performance of non-empirically tuned long-range corrected hybrid functionals for the prediction of vertical ionization potentials (IPs) and electron affinities (EAs) is assessed for a set of 24 organic acceptor molecules. Basis set extrapolated coupled cluster singles, doubles, and perturbative triples [CCSD(T)] calculations serve as a reference for this study. Compared to standard exchange-correlation functionals, tuned long-range corrected hybrid functionals produce highly reliable results for vertical IPs and EAs, yielding mean absolute errors on par with computationally more demanding GW calculations. In particular, it is demonstrated that long-range corrected hybrid functionals serve as ideal starting points for non-self-consistent GW calculations. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.5b00873 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 605 EP - 614 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Knight, Joseph W. A1 - Wang, Xiaopeng A1 - Gallandi, Lukas A1 - Dolgounitcheva, Olga A1 - Ren, Xinguo A1 - Ortiz, J. Vincent A1 - Rinke, Patrick A1 - Körzdörfer, Thomas A1 - Marom, Noa T1 - Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules III: A Benchmark of GW Methods JF - Journal of chemical theory and computation N2 - The performance of different GW methods is assessed for a set of 24 organic acceptors. Errors are evaluated with respect to coupled cluster singles, doubles, and perturbative triples [CCSD(T)] reference data for the vertical ionization potentials (IPs) and electron affinities (EAs), extrapolated to the complete basis set limit. Additional comparisons are made to experimental data, where available. We consider fully self-consistent GW (scGW), partial self-consistency in the Green’s function (scGW0), non-self-consistent G0W0 based on several mean-field starting points, and a “beyond GW” second-order screened exchange (SOSEX) correction to G0W0. We also describe the implementation of the self-consistent Coulomb hole with screened exchange method (COHSEX), which serves as one of the mean-field starting points. The best performers overall are G0W0+SOSEX and G0W0 based on an IP-tuned long-range corrected hybrid functional with the former being more accurate for EAs and the latter for IPs. Both provide a balanced treatment of localized vs delocalized states and valence spectra in good agreement with photoemission spectroscopy (PES) experiments. Y1 - 2016 U6 - https://doi.org/10.1021/acs.jctc.5b00871 SN - 1549-9618 SN - 1549-9626 VL - 12 SP - 615 EP - 626 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Senge, Mathias O. A1 - Flanagan, Keith J. A1 - Ryan, Aoife A. A1 - Ryppa, Claudia A1 - Donath, Mandy A1 - Twamley, Brendan T1 - Conformational and structural studies of meso monosubstituted metalloporphyrins-Edge-on molecular interactions of porphyrins in crystals JF - Tetrahedron N2 - A series of meso monosubstituted metalloporphyrins were synthesized to assess the structural chemistry of porphyrins with only one substituent. The structures of four nickel(II) and zinc(II) complexes with either alkyl or aryl residues indicate primarily planar macrocycles. This gives rise to a different type of pi-interactions in the crystal and the formation of dimeric, trimeric or tetrameric porphyrin units that function as building blocks for the overall crystal structure. Notably, some structures exhibit a unique edge-on packing of porphyrins, while the molecules of (5-n-butylporphyrinato)nickel(II) forms an unusual bilayer type structure where rows of two porphyrin macrocycles are separated by the alkyl residues arranged in a head-to-head fashion. This adds to the canon of intermolecular porphyrin packing arrangements and is of relevance for the preparation of ordered nanoscopic porphyrin devices. (C) 2015 Elsevier Ltd. All rights reserved. KW - Porphyrins KW - Conformational analysis KW - Tetrapyrroles KW - Crystal structure KW - Crystal packing Y1 - 2016 U6 - https://doi.org/10.1016/j.tet.2015.11.008 SN - 0040-4020 VL - 72 SP - 105 EP - 115 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Rumschöttel, Jens A1 - Kosmella, Sabine A1 - Prietzel, Claudia Christina A1 - Appelhans, Dietmar A1 - Koetz, Joachim T1 - Change in size, morphology and stability of DNA polyplexes with hyperbranched poly(ethyleneimines) containing bulky maltose units JF - Colloids and surfaces : an international journal devoted to fundamental and applied research on colloid and interfacial phenomena in relation to systems of biological origin ; B, Biointerfaces N2 - Polyplexes between Salmon DNA and non-modified hyperbranched poly(ethyleneimines) of varying molar mass, i.e., PEI(5 k) with 5000 g/mol and PEI(25 k) with 25,000 g/mol, and modified PEI(5 k) with maltose units (PEI-Mal) were investigated in dependence on the molar N/P ratio by using dynamic light scattering (DLS), zeta potential measurements, micro differential scanning calorimetry (mu-DSC), scanning-transmission electron microscopy (STEM), and cryo-scanning electron microscopy (cryo-SEM). A reloading of the polyplexes can be observed by adding the unmodified PEI samples of different molar mass. In excess of PEI a morphological transition from core-shell particles (at N/P 8) to loosely packed onion-like polyplexes (at N/P 40) is observed. The shift of the DSC melting peak from 88 degrees C to 76 degrees C indicates a destabilization of the DNA double helix due to the complexation with the unmodified PEI. Experiments with the maltose-modified PEI show a reloading already at a lower N/P ratio. Due to the presence of the sugar units in the periphery of the polycation electrostatic interactions between DNA become weaker, but cooperative H-bonding forces are reinforced. The resulting less-toxic, more compact polyplexes in excess of the PEI-Mal with two melting points and well distributed DNA segments are of special interest for extended gene delivery experiments. (C) 2015 Elsevier B.V. All rights reserved. KW - DNA complexation KW - Polyplexes KW - Maltose-modified poly(ethyleneimine) KW - Morphology Y1 - 2016 U6 - https://doi.org/10.1016/j.colsurfb.2015.11.061 SN - 0927-7765 SN - 1873-4367 VL - 138 SP - 78 EP - 85 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Cywinski, Piotr J. A1 - Pietraszkiewicz, Marek A1 - Maciejczyk, Michal A1 - Gorski, Krzysztof A1 - Hammann, Tommy A1 - Liermann, Konstanze A1 - Paulke, Bernd-Reiner A1 - Löhmannsröben, Hans-Gerd T1 - Total protein concentration quantification using nanobeads with a new highly luminescent terbium(III) complex JF - RSC Advances N2 - Total protein concentration (TPC) is a key parameter in many biochemical experiments and its quantification is often necessary for isolation, separation, and analysis of proteins. A sensitive and rapid nanobead-based TPC quantification assay based on Forster Resonance Energy Transfer (FRET) has been developed. A new, highly luminescent Tb(III) complex has been synthesised and applied as donor in this FRET assay with an organic dye (Cy5) as acceptor. FRET-induced changes in luminescence have been investigated both at donor and acceptor emission wavelength using time-resolved luminescence spectroscopy with time-gated detection. In the assay, the Tb(III) complex and fine-tuned polyglycidyl methacrylate (PGMA) nanobeads ensure that an improvement in sensitivity and background reduction is achieved. Using 40 nm large PGMA nanobeads loaded with the Tb(III) complex, it is possible to determine TPC down to 50 ng mL(-1) in just 10 minutes. Through specific assay components the sensitivity has been improved when compared to existing nanobead-based assays and to currently known commercial methods. Additionally, the assay is relatively insensitive to the presence of contaminants, such as non-ionic detergents commonly found in biological samples. Due to no need for any centrifugal steps, this mix-and-measure bioassay can easily be implemented into routine TPC quantification protocols in biochemical laboratories. Y1 - 2016 U6 - https://doi.org/10.1039/c6ra23207h SN - 2046-2069 VL - 6 SP - 115068 EP - 115073 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Omorogie, Martins O. A1 - Babalola, Jonathan Oyebamiji A1 - Unuabonah, Emmanuel I. A1 - Song, Weiguo A1 - Gong, Jian Ru T1 - Efficient chromium abstraction from aqueous solution using a low-cost biosorbent: Nauclea diderrichii seed biomass waste JF - Journal of Saudi Chemical Society N2 - Toxic Cr(III) which poses environmental hazard to flora and fauna was efficiently abstracted by low-cost Nauclea diderrichii seed biomass (NDS) with good sequestral capacity for this metal was investigated in this study. The NDS surface analyses showed that it has a specific surface area of 5.36 m(2)/g and pHpzc of 4.90. Thermogravimetric analysis of NDS showed three consecutive weight losses from 50-200 degrees C (ca. 5%), 200-400 C (ca. 35%), >400 degrees C (ca. 10%), corresponding to external water molecules, structural water molecules and heat induced condensation reactions respectively. Differential thermogram of NDS presented a large endothermic peak between 20-510 degrees C suggesting bond breakage and dissociation with the ultimate release of small molecules. The experimental data showed kinetically fast biosorption with increased initial Cr(III) concentrations, indicating the role of external mass transfer mechanism as the rate controlling mechanism in this adsorption process. The Langmuir biosorption capacity of NDS was 483.81 mg/g. The use of the corrected Akaike Information Criterion tool for ranking equilibrium models suggested that the Freundlich model best described the experimental data, which is an indication of the heterogeneous nature of the active sites on the surface of NDS. N. diderrichii seed biomass is an easily sourced, cheap and environmental friendly biosorbent which will serve as a good and cost effective alternative to activated carbon for the treatment of polluted water and industrial effluents. (C) 2012 King Saud University. Production and hosting by Elsevier B.V. All rights reserved. KW - Biomass KW - Equilibrium KW - External mass transfer KW - Kinetics KW - Adsorption KW - Water Y1 - 2016 U6 - https://doi.org/10.1016/j.jscs.2012.09.017 SN - 1319-6103 SN - 2212-4640 VL - 20 SP - 49 EP - 57 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Liebig, Ferenc A1 - Sarhan, Radwan Mohamed A1 - Prietzel, Claudia Christina A1 - Reinecke, Antje A1 - Koetz, Joachim T1 - "Green" gold nanotriangles: synthesis, purification by polyelectrolyte/micelle depletion flocculation and performance in surface-enhanced Raman scattering JF - RSC Advances N2 - The aim of this study was to develop a one-step synthesis of gold nanotriangles (NTs) in the presence of mixed phospholipid vesicles followed by a separation process to isolate purified NTs. Negatively charged vesicles containing AOT and phospholipids, in the absence and presence of additional reducing agents (polyampholytes, polyanions or low molecular weight compounds), were used as a template phase to form anisotropic gold nanoparticles. Upon addition of the gold chloride solution, the nucleation process is initiated and both types of particles, i.e., isotropic spherical and anisotropic gold nanotriangles, are formed simultaneously. As it was not possible to produce monodisperse nanotriangles with such a one-step procedure, the anisotropic nanoparticles needed to be separated from the spherical ones. Therefore, a new type of separation procedure using combined polyelectrolyte/micelle depletion flocculation was successfully applied. As a result of the different purification steps, a green colored aqueous dispersion was obtained containing highly purified, well-defined negatively charged flat nanocrystals with a platelet thickness of 10 nm and an edge length of about 175 nm. The NTs produce promising results in surface-enhanced Raman scattering. Y1 - 2016 U6 - https://doi.org/10.1039/c6ra04808k SN - 2046-2069 VL - 6 SP - 33561 EP - 33568 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Paz, Cristian A1 - Becerra, Jose A1 - Silva, Mario A1 - Cabrera-Pardo, Jaime A1 - Burgos, Viviana A1 - Heydenreich, Matthias A1 - Schmidt, Bernd T1 - (-)-8-Oxohobartine a New Indole Alkaloid from Aristotelia chilensis (Mol.) Stuntz JF - Records of Natural Products N2 - The fruit of Aristotelia chilensis is considered a "super fruit" due to its high concentration of polyphenols displaying exceptional antioxidant capacities ORAC. From maqui berries have been reported several anthocyanins and glycosylated flavonoids, those benefits increase the attention to restudy the plant. From the leaves of A. chilensis several indole alkaloids have been reported, we in addition to aristoteline, aristone, aristoquinoline and 3-fromylindole report the spectroscopic elucidation of 8-oxo-9-dehydromakomakine (1), hobartine (2) and a new alkaloid named 8-oxohobartine (3). Compound 1 to 3 did not show bactericidal activity against E. coli and S. aureus till 200 mu g. KW - Aristotelia chilensis KW - indole alkaloids KW - 8-oxohobartine Y1 - 2016 SN - 1307-6167 VL - 10 SP - 68 EP - 73 PB - ACG Publications CY - Gebze-Kocaeli ER - TY - JOUR A1 - Braune, Steffen A1 - Gross, M. A1 - Walter, M. A1 - Zhou, Shengqiang A1 - Dietze, Siegfried A1 - Rutschow, S. A1 - Lendlein, Andreas A1 - Tschoepe, C. A1 - Jung, Friedrich T1 - Adhesion and activation of platelets from subjects with coronary artery disease and apparently healthy individuals on biomaterials JF - Journal of biomedical materials research : an official journal of the Society for Biomaterials, the Japanese Society for Biomaterials; the Australian Society for Biomaterials N2 - On the basis of the clinical studies in patients with coronary artery disease (CAD) presenting an increased percentage of activated platelets, we hypothesized that hemocompatibility testing utilizing platelets from healthy individuals may result in an underestimation of the materials' thrombogenicity. Therefore, we investigated the interaction of polymer-based biomaterials with platelets from CAD patients in comparison to platelets from apparently healthy individuals. In vitro static thrombogenicity tests revealed that adherent platelet densities and total platelet covered areas were significantly increased for the low (polydimethylsiloxane, PDMS) and medium (Collagen) thrombogenic surfaces in the CAD group compared to the healthy subjects group. The area per single platelet—indicating the spreading and activation of the platelets—was markedly increased on PDMS treated with PRP from CAD subjects. This could not be observed for collagen or polytetrafluoroethylene (PTFE). For the latter material, platelet adhesion and surface coverage did not differ between the two groups. Irrespective of the substrate, the variability of these parameters was increased for CAD patients compared to healthy subjects. This indicates a higher reactivity of platelets from CAD patients compared to the healthy individuals. Our results revealed, for the first time, that utilizing platelets from apparently healthy donors bears the risk of underestimating the thrombogenicity of polymer-based biomaterials. KW - platelets KW - biomaterials KW - hemocompatibility KW - cardiovascular disease KW - cardiovascular implant Y1 - 2016 U6 - https://doi.org/10.1002/jbm.b.33366 SN - 1552-4973 SN - 1552-4981 VL - 104 SP - 210 EP - 217 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Omorogie, Martins O. A1 - Babalola, Jonathan Oyebamiji A1 - Unuabonah, Emmanuel I. A1 - Gong, Jian R. T1 - Clean technology approach for the competitive binding of toxic metal ions onto MnO2 nano-bioextractant JF - Clean technologies and environmental policy N2 - The competitive extraction of Cr(III) onto Nauclea diderrichii seed epicarp doped with MnO2 nanoparticles (MnO2 nano-bioextractant (MNB)) in a single and binary batch system was studied. For validity of experimental data, chi square test, root mean square error, sum of the square errors, hybrid fractional error function, Marquart’s percent standard deviation and standard absolute error were used. Among the kinetic models used, pseudo-second-order and Langmuir equations gave the best fits for the experimental data, with qe (mg g) for the uptake of Cr(III) in single metal system onto MNB, then Cr(III) with Cd(II), Pb(II), Hg(II), KCl and CaCl2 in binary metal systems onto MNB were 2.611, then 1.989, 1.016, 2.208, 1.249 and 1.868 from kinetic standpoint, respectively. The initial sorption rates, h (mg/g/min), and half lives, t1/2 (min), for the uptake of Cr(III) in single metal system onto MNB, then Cr(III) with Cd(II), Pb(II), Hg(II), KCl and CaCl2 in binary metal system onto MNB were 3.497, then 2.311, 2.274, 0.242, 2.956, 45.568 and 0.747, then 5.769, 1.766, 12.144, 1.762, and 2.415, respectively. Physicochemical surface analyses such as pH of point of zero charge, Brunauer–Emmett–Teller single point and multi-point techniques for surface area analyses, scanning electron microscopy and transmission electron microscopy were done on MNB and MnO2 nanoparticles in order to understand their surface microstructures. Desorption study showed that MNB can be recycled and used for future study. Hence, MNB showed good potential to remediate Cr(III) from wastewaters and polluted water. KW - Nauclea diderrichii KW - Nano-bioextractant KW - Doping KW - Kinetics KW - Mass transfer Y1 - 2016 U6 - https://doi.org/10.1007/s10098-015-1004-z SN - 1618-954X SN - 1618-9558 VL - 18 SP - 171 EP - 184 PB - Springer CY - New York ER - TY - JOUR A1 - Hildebrand, Viet A1 - Laschewsky, Andre A1 - Wischerhoff, Erik T1 - Modulating the solubility of zwitterionic poly((3methacrylamidopropyl)ammonioalkane sulfonate)s in water and aqueous salt solutions via the spacer group separating the cationic and the anionic moieties JF - Polymer Chemistry N2 - Complementary to the well-established zwitterionic monomer 3-((3-methacrylamidopropyl) dimethylammonio) propane-1-sulfonate (SPP), the closely related monomers 2-hydroxy-3-((3-methacrylamidopropyl) dimethylammonio) propane-1-sulfonate (SHPP) and 4-((3-methacrylamidopropyl) dimethylammonio)butane- 1-sulfonate (SBP) were synthesised and polymerised by reversible addition-fragmentation chain transfer (RAFT) polymerisation, using a fluorophore labeled RAFT agent. The polyzwitterions of systematically varied molar masses were characterised with respect to their solubility in water and aqueous salt solutions. Both poly(sulfobetaine)s show thermoresponsive behaviour in water, exhibiting phase separation at low temperatures and upper critical solution temperatures (UCST). For both polySHPP and polySBP, cloud points depend notably on the molar mass, and are much higher in D2O than in H2O. Also, the cloud points are effectively modulated by the addition of salts. The individual effects can be in parts correlated to the Hofmeister series for the anions studied. Still, they depend in a complex way on the concentration and the nature of the added electrolytes, on the one hand, and on the detailed nature of the spacer group separating the anionic and the cationic charges of the betaine moiety, on the other hand. As anticipated, the cloud points of polySBP are much higher than the ones of the analogous polySPP of identical molar mass. Surprisingly, the cloud points of polySHPP are also somewhat higher than the ones of their polySPP analogues, despite the additional hydrophilic hydroxyl group present in the spacer separating the ammonium and the sulfonate moieties. These findings point to a complicated interplay of the various hydrophilic components in polyzwitterions with respect to their overall hydrophilicity. Thus, the spacer group in the betaine moiety proves to be an effective additional molecular design parameter, apparently small variations of which strongly influence the phase behaviour of the polyzwitterions in specific aqueous environments. Y1 - 2016 U6 - https://doi.org/10.1039/c5py01642h SN - 1759-9954 SN - 1759-9962 VL - 7 SP - 731 EP - 740 PB - Royal Society of Chemistry CY - Cambridge ER -