@article{KopecLapokLaschewskyetal.2014, author = {Kopec, Maciej and Lapok, Lukasz and Laschewsky, Andr{\´e} and Zapotoczny, Szczepan and Nowakowska, Maria}, title = {Polyelectrolyte multilayers with perfluorinated phthalocyanine selectively entrapped inside the perfluorinated nanocompartments}, series = {Soft matter}, volume = {10}, journal = {Soft matter}, number = {10}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1744-683X}, doi = {10.1039/c2sm26938d}, pages = {1481 -- 1488}, year = {2014}, abstract = {A novel perfluorinated magnesium phthalocyanine (MgPcF64) was synthesized and employed to probe nanodomains in hydrophobically modified, amphiphilic cationic polyelectrolytes bearing alkyl and/or fluoroalkyl side chains. MgPcF64 was found to be solubilized exclusively in the aqueous solutions of the fluorocarbon modified polycations, occupying the perfluorinated nanocompartments provided, while analogous polyelectrolytes with alkyl side chains forming hydrocarbon nanocompartments could not host the MgPcF64 dye. Multilayer films were fabricated by means of the layer-by-layer (LbL) deposition method using sodium poly(styrene sulfonate) as a polyanion. Linear multilayer growth was confirmed by UV-Vis spectroscopy and spectroscopic ellipsometry. Atomic force microscopy studies indicated that the micellar conformation of the polycations is preserved in the multilayer films. Fluorescence spectroscopy measurements confirmed that MgPcF64 stays embedded inside the fluorocarbon domains after the deposition process. This facile way of selectively incorporating water-insoluble, photoactive molecules into the structure of polyelectrolyte multilayers may be utilized for nanoengineering of ultrathin film-based optoelectronic devices.}, language = {en} } @article{ErmeydanCabaneGierlingeretal.2014, author = {Ermeydan, Mahmut Ali and Cabane, Etienne and Gierlinger, Notburga and Koetz, Joachim and Burgert, Ingo}, title = {Improvement of wood material properties via in situ polymerization of styrene into tosylated cell walls}, series = {RSC Advances}, volume = {4}, journal = {RSC Advances}, number = {25}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2046-2069}, doi = {10.1039/c4ra00741g}, pages = {12981 -- 12988}, year = {2014}, abstract = {As an engineering material derived from renewable resources, wood possesses excellent mechanical properties in view of its light weight but also has some disadvantages such as low dimensional stability upon moisture changes and low durability against biological attack. Polymerization of hydrophobic monomers in the cell wall is one of the potential approaches to improve the dimensional stability of wood. A major challenge is to insert hydrophobic monomers into the hydrophilic environment of the cell walls, without increasing the bulk density of the material due to lumen filling. Here, we report on an innovative and simple method to insert styrene monomers into tosylated cell walls (i.e. -OH groups from natural wood polymers are reacted with tosyl chloride) and carry out free radical polymerization under relatively mild conditions, generating low wood weight gains. In-depth SEM and confocal Raman microscopy analysis are applied to reveal the distribution of the polystyrene in the cell walls and the lumen. The embedding of polystyrene in wood results in reduced water uptake by the wood cell walls, a significant increase in dimensional stability, as well as slightly improved mechanical properties measured by nanoindentation.}, language = {en} } @article{FudickarLinker2014, author = {Fudickar, Werner and Linker, Torsten}, title = {Intermediates in the formation and thermolysis of peroxides from oxidations with singlet oxygen}, series = {Australian journal of chemistry}, volume = {67}, journal = {Australian journal of chemistry}, number = {3}, publisher = {CSIRO}, address = {Clayton}, issn = {0004-9425}, doi = {10.1071/CH13423}, pages = {320 -- 327}, year = {2014}, abstract = {Herein we describe the recent mechanistic understandings of the singlet oxygen ene reaction to give hydroperoxides and the [4+2] cycloaddition affording endoperoxides. Both experimental findings and theoretical work conclude in the formation of intermediates structurally similar to perepoxides during the ene reaction. Such intermediates mainly control the regio- and stereoselectivities of this reaction class. For the [4+2] cycloaddition, both a synchronous concerted reaction (benzene, naphthalenes) and a stepwise reaction with a non-symmetric zwitterionic intermediate (larger acenes) have been found. The thermolysis of endoperoxides derived from acenes proceeds stepwise for anthracenes, but in a concerted manner for less stable adducts such as naphthalene.}, language = {en} } @article{BauerGodecMetzler2014, author = {Bauer, Maximilian and Godec, Aljaz and Metzler, Ralf}, title = {Diffusion of finite-size particles in two-dimensional channels with random wall configurations}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {13}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c3cp55160a}, pages = {6118 -- 6128}, year = {2014}, abstract = {Diffusion of chemicals or tracer molecules through complex systems containing irregularly shaped channels is important in many applications. Most theoretical studies based on the famed Fick-Jacobs equation focus on the idealised case of infinitely small particles and reflecting boundaries. In this study we use numerical simulations to consider the transport of finite-size particles through asymmetrical two-dimensional channels. Additionally, we examine transient binding of the molecules to the channel walls by applying sticky boundary conditions. We consider an ensemble of particles diffusing in independent channels, which are characterised by common structural parameters. We compare our results for the long-time effective diffusion coefficient with a recent theoretical formula obtained by Dagdug and Pineda}, language = {en} } @article{CywinskiNonoCharbonniereetal.2014, author = {Cywinski, Piotr J. and Nono, Katia Nchimi and Charbonniere, Loic J. and Hammann, Tommy and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {Photophysical evaluation of a new functional terbium complex in FRET-based time-resolved homogenous fluoroassays}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {13}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c3cp54883j}, pages = {6060 -- 6067}, year = {2014}, abstract = {A new functional luminescent lanthanide complex (LLC) has been synthesized with terbium as a central lanthanide ion and biotin as a functional moiety. Unlike in typical lanthanide complexes assembled via carboxylic moieties, in the presented complex, four phosphate groups are chelating the central lanthanide ion. This special chemical assembly enhances the complex stability in phosphate buffers conventionally used in biochemistry. The complex synthesis strategy and photophysical properties are described as well as the performance in time-resolved Forster Resonance Energy Transfer (FRET) assays. In those assays, this biotin-LLC transferred energy either to acceptor organic dyes (Cy5 or AF680) labelled on streptavidin or to quantum dots (QD655 or QD705) surfacefunctionalised with streptavidins. The permanent spatial donor-acceptor proximity is assured through strong and stable biotin-streptavidin binding. The energy transfer is evidenced from the quenching observed in donor emission and from a decrease in donor luminescence decay, both associated with simultaneous increase in acceptor intensity and in the decay time. The dye-based assays are realised in TRIS and in PBS, whereas QD-based systems are studied in borate buffer. The delayed emission analysis allows for quantifying the recognition process and for auto-fluorescence-free detection, which is particularly relevant for application in bioanalysis. In accordance with Forster theory, Forsterradii (R0) were found to be around 60 angstrom for organic dyes and around 105 angstrom for QDs. The FRET efficiency (Z) reached 80\% and 25\% for dye and QD acceptors, respectively. Physical donor-acceptor distances (r) have been determined in the range 45-60 angstrom for organic dye acceptors, while for acceptor QDs between 120 angstrom and 145 angstrom. This newly synthesised biotin-LLC extends the class of highly sensitive analytical tools to be applied in the bioanalytical methods such as time-resolved fluoroimmunoassays (TR-FIA), luminescent imaging and biosensing.}, language = {en} } @article{MondalBhuniaKellingetal.2014, author = {Mondal, Suvendu Sekhar and Bhunia, Asamanjoy and Kelling, Alexandra and Schilde, Uwe and Janiak, Christoph and Holdt, Hans-J{\"u}rgen}, title = {A supramolecular Co(II)(14)- metal-organic cube in a hydrogen-bonded network and a Co(II)-organic framework with a flexible methoxy substituent}, series = {Chemical communications}, volume = {50}, journal = {Chemical communications}, number = {41}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1359-7345}, doi = {10.1039/c3cc49698h}, pages = {5441 -- 5443}, year = {2014}, abstract = {The reaction of 4,5-dicyano-2-methoxyimidazole (L1) with Co(NO3)(2.) 6H(2)O under solvothermal conditions in DMF, a MOF, IFP-8 and a hydrogen-bonded network consisting of tetradecanuclear Co(II)(14)-metal organic cube (1) are achieved. 1 shows the bcu net with 14 cobalt atoms.}, language = {en} } @article{SangoroIacobAgapovetal.2014, author = {Sangoro, Joshia R. and Iacob, C. and Agapov, A. L. and Wang, Yangyang and Berdzinski, Stefan and Rexhausen, Hans and Strehmel, Veronika and Friedrich, C. and Sokolov, A. P. and Kremer, F.}, title = {Decoupling of ionic conductivity from structural dynamics in polymerized ionic liquids}, series = {Soft matter}, volume = {10}, journal = {Soft matter}, number = {20}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1744-683X}, doi = {10.1039/c3sm53202j}, pages = {3536 -- 3540}, year = {2014}, abstract = {Charge transport and structural dynamics in low molecular weight and polymerized 1-vinyl-3-pentylimidazolium bis(trifluoromethylsulfonyl) imide ionic liquids (ILs) are investigated by a combination of broadband dielectric spectroscopy, dynamic mechanical spectroscopy and differential scanning calorimetry. While the dc conductivity and fluidity exhibit practically identical temperature dependence for the non-polymerized IL, a significant decoupling of ionic conduction from structural dynamics is observed for the polymerized IL. In addition, the dc conductivity of the polymerized IL exceeds that of its molecular counterpart by four orders of magnitude at their respective calorimetric glass transition temperatures. This is attributed to the unusually high mobility of the anions especially at lower temperatures when the structural dynamics is significantly slowed down. A simple physical explanation of the possible origin of the remarkable decoupling of ionic conductivity from structural dynamics is proposed.}, language = {en} } @article{SarauliXuDietzeletal.2014, author = {Sarauli, David and Xu, Chenggang and Dietzel, Birgit and Schulz, Burkhard and Lisdat, Fred}, title = {A multilayered sulfonated polyaniline network with entrapped pyrroloquinoline quinone-dependent glucose dehydrogenase: tunable direct bioelectrocatalysis}, series = {Journal of materials chemistry : B, Materials for biology and medicine}, volume = {2}, journal = {Journal of materials chemistry : B, Materials for biology and medicine}, number = {21}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2050-750X}, doi = {10.1039/c4tb00336e}, pages = {3196 -- 3203}, year = {2014}, abstract = {A feasible approach to construct multilayer films of sulfonated polyanilines - PMSA1 and PABMSA1 containing different ratios of aniline, 2-methoxyaniline-5-sulfonic acid (MAS) and 3-aminobenzoic acid (AB), with the entrapped redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) on Au and ITO electrode surfaces, is described. The formation of layers has been followed and confirmed by electrochemical impedance spectroscopy (EIS), which demonstrates that the multilayer assembly can be achieved in a progressive and uniform manner. The gold and ITO electrodes subsequently modified with PMSA1:PQQ-GDH and PABMSA1 films are studied by cyclic voltammetry (CV) and UV-Vis spectroscopy which show a significant direct bioelectrocatalytical response to the oxidation of the substrate glucose without any additional mediator. This response correlates linearly with the number of deposited layers. Furthermore, the constructed polymer/enzyme multilayer system exhibits a rather good long-term stability, since the catalytic current response is maintained for more than 60\% of the initial value even after two weeks of storage. This verifies that a productive interaction of the enzyme embedded in the film of substituted polyaniline can be used as a basis for the construction of bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction.}, language = {en} } @article{ErmeydanCabaneHassetal.2014, author = {Ermeydan, Mahmut Ali and Cabane, Etienne and Hass, Philipp and Koetz, Joachim and Burgert, Ingo}, title = {Fully biodegradable modification of wood for improvement of dimensional stability and water absorption properties by poly(epsilon-caprolactone) grafting into the cell walls}, series = {Green chemistry : an international journal and green chemistry resource}, volume = {16}, journal = {Green chemistry : an international journal and green chemistry resource}, number = {6}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9262}, doi = {10.1039/c4gc00194j}, pages = {3313 -- 3321}, year = {2014}, abstract = {Materials derived from renewable resources are highly desirable in view of more sustainable manufacturing. Among the available natural materials, wood is one of the key candidates, because of its excellent mechanical properties. However, wood and wood-based materials in engineering applications suffer from various restraints, such as dimensional instability upon humidity changes. Several wood modification treatments increase water repellence, but the insertion of hydrophobic polymers can result in a composite material which cannot be considered as renewable anymore. In this study, we report on the grafting of the fully biodegradable poly(epsilon-caprolactone) (PCL) inside the wood cell walls by Sn(Oct)(2) catalysed ring-opening polymerization (ROP). The presence of polyester chains within the wood cell wall structure is monitored by confocal Raman imaging and spectroscopy as well as scanning electron microscopy. Physical tests reveal that the modified wood is more hydrophobic due to the bulking of the cell wall structure with the polyester chains, which results in a novel fully biodegradable wood material with improved dimensional stability.}, language = {en} } @article{NeffevonRuestenLangeBrauneetal.2014, author = {Neffe, Axel T. and von R{\"u}sten-Lange, Maik and Braune, Steffen and L{\"u}tzow, Karola and Roch, Toralf and Richau, Klaus and Kr{\"u}ger, Anne and Becherer, Tobias and Th{\"u}nemann, Andreas F. and Jung, Friedrich and Haag, Rainer and Lendlein, Andreas}, title = {Multivalent grafting of hyperbranched oligo- and polyglycerols shielding rough membranes to mediate hemocompatibility}, series = {Journal of materials chemistry : B, Materials for biology and medicine}, volume = {2}, journal = {Journal of materials chemistry : B, Materials for biology and medicine}, number = {23}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2050-750X}, doi = {10.1039/c4tb00184b}, pages = {3626 -- 3635}, year = {2014}, abstract = {Hemocompatible materials are needed for internal and extracorporeal biomedical applications, which should be realizable by reducing protein and thrombocyte adhesion to such materials. Polyethers have been demonstrated to be highly efficient in this respect on smooth surfaces. Here, we investigate the grafting of oligo- and polyglycerols to rough poly(ether imide) membranes as a polymer relevant to biomedical applications and show the reduction of protein and thrombocyte adhesion as well as thrombocyte activation. It could be demonstrated that, by performing surface grafting with oligo-and polyglycerols of relatively high polydispersity (>1.5) and several reactive groups for surface anchoring, full surface shielding can be reached, which leads to reduced protein adsorption of albumin and fibrinogen. In addition, adherent thrombocytes were not activated. This could be clearly shown by immunostaining adherent proteins and analyzing the thrombocyte covered area. The presented work provides an important strategy for the development of application relevant hemocompatible 3D structured materials.}, language = {en} } @article{PlehnMegowMay2014, author = {Plehn, Thomas and Megow, J{\"o}rg and May, Volkhard}, title = {Concerted charge and energy transfer processes in a highly flexible fullerene-dye system: a mixed quantum-classical study}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {25}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c4cp01081g}, pages = {12949 -- 12958}, year = {2014}, abstract = {Photoinduced excitation energy transfer and accompanying charge separation are elucidated for a supramolecular system of a single fullerene covalently linked to six pyropheophorbide-a dye molecules. Molecular dynamics simulations are performed to gain an atomistic picture of the architecture and the surrounding solvent. Excitation energy transfer among the dye molecules and electron transfer from the excited dyes to the fullerene are described by a mixed quantum-classical version of the Forster rate and the semiclassical Marcus rate, respectively. The mean characteristic time of energy redistribution lies in the range of 10 ps, while electron transfer proceeds within 150 ps. In between, on a 20 to 50 ps time-scale, conformational changes take place in the system. This temporal hierarchy of processes guarantees efficient charge separation, if the structure is exposed to a solvent. The fast energy transfer can adopt the dye excitation to the actual conformation. In this sense, the probability to achieve charge separation is large enough since any dominance of unfavorable conformations that exhibit a large dye-fullerene distance is circumvented. And the slow electron transfer may realize an averaging with respect to different conformations. To confirm the reliability of our computations, ensemble measurements on the charge separation dynamics are simulated and a very good agreement with the experimental data is obtained.}, language = {en} } @article{GrunzelPilarekSteinbruecketal.2014, author = {Grunzel, Petra and Pilarek, Maciej and Steinbrueck, Doerte and Neubauer, Antje and Brand, Eva and Kumke, Michael Uwe and Neubauer, Peter and Krause, Mirja}, title = {Mini-scale cultivation method enables expeditious plasmid production in Escherichia coli}, series = {Biotechnology journal : systems \& synthetic biology, nanobiotech, medicine}, volume = {9}, journal = {Biotechnology journal : systems \& synthetic biology, nanobiotech, medicine}, number = {1}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1860-6768}, doi = {10.1002/biot.201300177}, pages = {128 -- 136}, year = {2014}, abstract = {The standard procedure in the lab for plasmid isolation usually involves a 2-mL, 16 h over-night cultivation in 15-mL bioreaction tubes in LB medium. This is time consuming, and not suitable for high-throughput applications. This study shows that it is possible to produce plasmid DNA (pDNA) in a 1.5-mL microcentrifuge tube with only 100 L cultivation volume in less than 7 h with a simple protocol. Compared with the standard LB cultivation for pDNA production reaching a final pDNA concentration range of 1.5-4 mu g mL(-1), a 6- to 10-fold increase in plasmid concentration (from 10 up to 25 mu g mL(-1) cultivation volume) is achieved using an optimized medium with an internal substrate delivery system (EnBase (R)). Different strains, plasmids, and the applicability of different inoculation tools (i.e. different starting ODs) were compared, demonstrating the robustness of the system. Additionally, dissolved oxygen was monitored in real time online, indicating that under optimized conditions oxygen limitation can be avoided. We developed a simple protocol with a significantly decreased procedure time, enabling simultaneous handling of more samples, while a consistent quality and a higher final pDNA concentration are ensured.}, language = {en} } @article{EhlertUngerSaalfrank2014, author = {Ehlert, Christopher and Unger, Wolfgang E. S. and Saalfrank, Peter}, title = {C K-edge NEXAFS spectra of graphene with physical and chemical defects: a study based on density functional theory}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {27}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c4cp01106f}, pages = {14083 -- 14095}, year = {2014}, abstract = {Recently, C K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of graphite (HOPG) surfaces have been measured for the pristine material, and for HOPG treated with either bromine or krypton plasmas (Lippitz et al., Surf. Sci., 2013, 611, L1). Changes of the NEXAFS spectra characteristic for physical (krypton) and/or chemical/physical modifications of the surface (bromine) upon plasma treatment were observed. Their molecular origin, however, remained elusive. In this work we study by density functional theory, the effects of selected point and line defects as well as chemical modifications on NEXAFS carbon K-edge spectra of single graphene layers. For Br-treated surfaces, also Br 3d X-ray Photoelectron Spectra (XPS) are simulated by a cluster approach, to identify possible chemical modifications. We observe that some of the defects related to plasma treatment lead to characteristic changes of NEXAFS spectra, similar to those in experiment. Theory provides possible microscopic origins for these changes.}, language = {en} } @article{WirthNeumannAntoniettietal.2014, author = {Wirth, Jonas and Neumann, Rainer and Antonietti, Markus and Saalfrank, Peter}, title = {Adsorption and photocatalytic splitting of water on graphitic carbon nitride: a combined first principles and semiempirical study}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {30}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c4cp02021a}, pages = {15917 -- 15926}, year = {2014}, abstract = {Graphitic carbon nitride, g-C3N4, is a promising organic photo-catalyst for a variety of redox reactions. In order to improve its efficiency in a systematic manner, however, a fundamental understanding of the microscopic interaction between catalyst, reactants and products is crucial. Here we present a systematic study of water adsorption on g-C3N4 by means of density functional theory and the density functional based tight-binding method as a prerequisite for understanding photocatalytic water splitting. We then analyze this prototypical redox reaction on the basis of a thermodynamic model providing an estimate of the overpotential for both water oxidation and H+ reduction. While the latter is found to occur readily upon irradiation with visible light, we derive a prohibitive overpotential of 1.56 eV for the water oxidation half reaction, comparing well with the experimental finding that in contrast to H-2 production O-2 evolution is only possible in the presence of oxidation cocatalysts.}, language = {en} } @article{JeonChechkinMetzler2014, author = {Jeon, Jae-Hyung and Chechkin, Aleksei and Metzler, Ralf}, title = {Scaled Brownian motion: a paradoxical process with a time dependent diffusivity for the description of anomalous diffusion}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {30}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c4cp02019g}, pages = {15811 -- 15817}, year = {2014}, abstract = {Anomalous diffusion is frequently described by scaled Brownian motion (SBM), a Gaussian process with a power-law time dependent diffusion coefficient. Its mean squared displacement is < x(2)(t) similar or equal to 2K(t)t with K(t) similar or equal to t(alpha-1) for 0 < alpha < 2. SBM may provide a seemingly adequate description in the case of unbounded diffusion, for which its probability density function coincides with that of fractional Brownian motion. Here we show that free SBM is weakly non-ergodic but does not exhibit a significant amplitude scatter of the time averaged mean squared displacement. More severely, we demonstrate that under confinement, the dynamics encoded by SBM is fundamentally different from both fractional Brownian motion and continuous time random walks. SBM is highly non-stationary and cannot provide a physical description for particles in a thermalised stationary system. Our findings have direct impact on the modelling of single particle tracking experiments, in particular, under confinement inside cellular compartments or when optical tweezers tracking methods are used.}, language = {en} } @article{WessigGerngrossPapeetal.2014, author = {Wessig, Pablo and Gerngross, Maik and Pape, Simon and Bruhns, Philipp and Weber, Jens}, title = {Novel porous materials based on oligospiroketals (OSK)}, series = {RSC Advances}, volume = {4}, journal = {RSC Advances}, number = {59}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2046-2069}, doi = {10.1039/c4ra04437a}, pages = {31123 -- 31129}, year = {2014}, abstract = {New porous materials based on covalently connected monomers are presented. The key step of the synthesis is an acetalisation reaction. In previous years we used acetalisation reactions extensively to build up various molecular rods. Based on this approach, investigations towards porous polymeric materials were conducted by us. Here we wish to present the results of these studies in the synthesis of 1D polyacetals and porous 3D polyacetals. By scrambling experiments with 1D acetals we could prove that exchange reactions occur between different building blocks (evidenced by MALDI-TOF mass spectrometry). Based on these results we synthesized porous 3D polyacetals under the same mild conditions.}, language = {en} } @article{ZborowskiKochKleinpeteretal.2014, author = {Zborowski, Krzysztof Kazimierz and Koch, Andreas and Kleinpeter, Erich and Proniewicz, Leonard Marian}, title = {Searching for aromatic celate rings. Oxygen versus Thio and Seleno Ligands}, series = {Zeitschrift f{\"u}r physikalische Chemie : international journal of research in physical chemistry and chemical physics}, volume = {228}, journal = {Zeitschrift f{\"u}r physikalische Chemie : international journal of research in physical chemistry and chemical physics}, number = {8}, publisher = {De Gruyter}, address = {Berlin}, issn = {0942-9352}, doi = {10.1515/zpch-2014-0528}, pages = {869 -- 878}, year = {2014}, abstract = {As a part of searching for fully aromatic chelate compounds, copper complexes of malondialdehyde as well as its sulfur and selenium derivatives were investigated using the DFT quantum chemical methods. Chelate complexes of both Cu(I) and Cu(II) ions wereconsidered. Aromaticity of the metal complexes studied were analyzed using NICS(0), NICS(1), PDI, I-ring, MCI, ICMCI and I-B aromaticity indices, and by TSNMRS visualizations of the spatial magnetic properties. It seems that partial aromaticityof studied chelates increases when oxygen atoms in malondialdehyde are replaced by sulfur and selenium.}, language = {en} } @article{XieHuangTitiricietal.2014, author = {Xie, Zai-Lai and Huang, Xing and Titirici, Maria-Magdalena and Taubert, Andreas}, title = {Mesoporous graphite nanoflakes via ionothermal carbonization of fructose and their use in dye removal}, series = {RSC Advances}, volume = {4}, journal = {RSC Advances}, number = {70}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2046-2069}, doi = {10.1039/c4ra05146g}, pages = {37423 -- 37430}, year = {2014}, abstract = {The large-scale green synthesis of graphene-type two-dimensional materials is still challenging. Herein, we describe the ionothermal synthesis of carbon-based composites from fructose in the iron-containing ionic liquid 1-butyl-3-methylimidazolium tetrachloridoferrate(III), [Bmim][FeCl4] serving as solvent, catalyst, and template for product formation. The resulting composites consist of oligo-layer graphite nanoflakes and iron carbide particles. The mesoporosity, strong magnetic moment, and high specific surface area of the composites make them attractive for water purification with facile magnetic separation. Moreover, Fe3Cfree graphite can be obtained via acid etching, providing access to fairly large amounts of graphite material. The current approach is versatile and scalable, and thus opens the door to ionothermal synthesis towards the larger-scale synthesis of materials that are, although not made via a sustainable process, useful for water treatment such as the removal of organic molecules.}, language = {en} } @article{SchmidtBehlLendleinetal.2014, author = {Schmidt, Christian and Behl, Marc and Lendlein, Andreas and Beuermann, Sabine}, title = {Synthesis of high molecular weight polyglycolide in supercritical carbon dioxide}, series = {RSC Advances}, volume = {4}, journal = {RSC Advances}, number = {66}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2046-2069}, doi = {10.1039/c4ra06815g}, pages = {35099 -- 35105}, year = {2014}, abstract = {Polyglycolide (PGA) is a biodegradable polymer with multiple applications in the medical sector. Here the synthesis of high molecular weight polyglycolide by ring-opening polymerization of diglycolide is reported. For the first time stabilizer free supercritical carbon dioxide (scCO(2)) was used as a reaction medium. scCO(2) allowed for a reduction in reaction temperature compared to conventional processes. Together with the lowering of monomer concentration and consequently reduced heat generation compared to bulk reactions thermal decomposition of the product occurring already during polymerization is strongly reduced. The reaction temperatures and pressures were varied between 120 and 150 degrees C and 145 to 1400 bar. Tin(II) ethyl hexanoate and 1-dodecanol were used as catalyst and initiator, respectively. The highest number average molecular weight of 31 200 g mol(-1) was obtained in 5 hours from polymerization at 120 degrees C and 530 bar. In all cases the products were obtained as a dry white powder. Remarkably, independent of molecular weight the melting temperatures were always at (219 +/- 2)degrees C.}, language = {en} } @article{HildebrandLaschewskyZehm2014, author = {Hildebrand, Viet and Laschewsky, Andr{\´e} and Zehm, Daniel}, title = {On the hydrophilicity of polyzwitterion poly (N, N-dimethyl-N(3-(methacrylamido)propyl)ammoniopropane sulfonate) in water, deuterated water, and aqueous salt solutions}, series = {Journal of biomaterials science : Polymer edition}, volume = {25}, journal = {Journal of biomaterials science : Polymer edition}, number = {14-15}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {0920-5063}, doi = {10.1080/09205063.2014.939918}, pages = {1602 -- 1618}, year = {2014}, language = {en} } @article{MetzlerJeonCherstvyetal.2014, author = {Metzler, Ralf and Jeon, Jae-Hyung and Cherstvy, Andrey G. and Barkai, Eli}, title = {Anomalous diffusion models and their properties: non-stationarity, non-ergodicity, and ageing at the centenary of single particle tracking}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {16}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {44}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/c4cp03465a}, pages = {24128 -- 24164}, year = {2014}, abstract = {Modern microscopic techniques following the stochastic motion of labelled tracer particles have uncovered significant deviations from the laws of Brownian motion in a variety of animate and inanimate systems. Such anomalous diffusion can have different physical origins, which can be identified from careful data analysis. In particular, single particle tracking provides the entire trajectory of the traced particle, which allows one to evaluate different observables to quantify the dynamics of the system under observation. We here provide an extensive overview over different popular anomalous diffusion models and their properties. We pay special attention to their ergodic properties, highlighting the fact that in several of these models the long time averaged mean squared displacement shows a distinct disparity to the regular, ensemble averaged mean squared displacement. In these cases, data obtained from time averages cannot be interpreted by the standard theoretical results for the ensemble averages. Here we therefore provide a comparison of the main properties of the time averaged mean squared displacement and its statistical behaviour in terms of the scatter of the amplitudes between the time averages obtained from different trajectories. We especially demonstrate how anomalous dynamics may be identified for systems, which, on first sight, appear to be Brownian. Moreover, we discuss the ergodicity breaking parameters for the different anomalous stochastic processes and showcase the physical origins for the various behaviours. This Perspective is intended as a guidebook for both experimentalists and theorists working on systems, which exhibit anomalous diffusion.}, language = {en} } @article{BrauneWalterSchulzeetal.2014, author = {Braune, Steffen and Walter, M. and Schulze, F. and Lendlein, Andreas and Jung, Friedrich}, title = {Changes in platelet morphology and function during 24 hours of storage}, series = {Clinical hemorheology and microcirculation : blood flow and vessels}, volume = {58}, journal = {Clinical hemorheology and microcirculation : blood flow and vessels}, number = {1}, publisher = {IOS Press}, address = {Amsterdam}, issn = {1386-0291}, doi = {10.3233/CH-141876}, pages = {159 -- 170}, year = {2014}, abstract = {For in vitro studies assessing the interaction of platelets with implant materials, common and standardized protocols for the preparation of platelet rich plasma (PRP) are lacking, which may lead to non-matching results due to the diversity of applied protocols. Particularly, the aging of platelets during prolonged preparation and storage times is discussed to lead to an underestimation of the material thrombogenicity. Here, we study the influence of whole blood-and PRP-storage times on changes in platelet morphology and function. Whole blood PFA100 closure times increased after stimulation with collagen/ADP and collagen/epinephrine. Twenty four hours after blood collection, both parameters were prolonged pathologically above the upper limit of the reference range. Numbers of circulating platelets, measured in PRP, decreased after four hours, but no longer after twenty four hours. Mean platelet volumes (MPV) and platelet large cell ratios (P-LCR, 12 fL - 40 fL) decreased over time. Immediately after blood collection, no debris or platelet aggregates could be visualized microscopically. After four hours, first debris and very small aggregates occurred. After 24 hours, platelet aggregates and also debris progressively increased. In accordance to this, the CASY system revealed an increase of platelet aggregates (up to 90 mu m diameter)with increasing storage time. The percentage of CD62P positive platelets and PF4 increased significantly with storage time in resting PRP. When soluble ADP was added to stored PRP samples, the number of activatable platelets decreased significantly over storage time. The present study reveals the importance of a consequent standardization in the preparation of WB and PRP. Platelet morphology and function, particularly platelet reactivity to adherent or soluble agonists in their surrounding milieu, changed rapidly outside the vascular system. This knowledge is of crucial interest, particularly in the field of biomaterial development for cardiovascular applications, and may help to define common standards in the in vitro hemocompatibility testing of biomaterials.}, language = {en} } @article{SchwarzeMuellerAstetal.2014, author = {Schwarze, Thomas and Mueller, Holger and Ast, Sandra and Steinbr{\"u}ck, Dorte and Eidner, Sascha and Geißler, Felix and Kumke, Michael Uwe and Holdt, Hans-J{\"u}rgen}, title = {Fluorescence lifetime-based sensing of sodium by an optode}, series = {Chemical communications}, volume = {50}, journal = {Chemical communications}, number = {91}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1359-7345}, doi = {10.1039/c4cc06112h}, pages = {14167 -- 14170}, year = {2014}, abstract = {We report a 1,2,3-triazol fluoroionophore for detecting Na+ that shows in vitro enhancement in the Na+-induced fluorescence intensity and decay time. The Na+-selective molecule 1 was incorporated into a hydrogel as a part of a fiber optical sensor. This sensor allows the direct determination of Na+ in the range of 1-10 mM by measuring reversible fluorescence decay time changes.}, language = {en} } @article{CommingesFrascaSuetterlinetal.2014, author = {Comminges, Clement and Frasca, Stefano and Suetterlin, Martin and Wischerhoff, Erik and Laschewsky, Andr{\´e} and Wollenberger, Ursula}, title = {Surface modification with thermoresponsive polymer brushes for a switchable electrochemical sensor}, series = {RSC Advances}, volume = {4}, journal = {RSC Advances}, number = {81}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2046-2069}, doi = {10.1039/c4ra07190e}, pages = {43092 -- 43097}, year = {2014}, abstract = {Elaboration of switchable surfaces represents an interesting way for the development of a new generation of electrochemical sensors. In this paper, a method for growing thermoresponsive polymer brushes from a gold surface pre-modified with polyethyleneimine (PEI), subsequent layer-by-layer polyelectrolyte assembly and adsorption of a charged macroinitiator is described. We propose an easy method for monitoring the coil-to-globule phase transition of the polymer brush using an electrochemical quartz crystal microbalance with dissipation (E-QCM-D). The surface of these polymer modified electrodes shows reversible switching from the swollen to the collapsed state with temperature. As demonstrated from E-QCM-D measurements using an original signal processing method, the switch is operating in three reversible steps related to different interfacial viscosities. Moreover, it is shown that the one electron oxidation of ferrocene carboxylic acid is dramatically affected by the change from the swollen to the collapsed state of the polymer brush, showing a spectacular 86\% decrease of the charge transfer resistance between the two states.}, language = {en} } @misc{Kleinpeter2014, author = {Kleinpeter, Erich}, title = {Quantification and visualization of the anisotropy effect in NMR spectroscopy by through-space NMR shieldings}, series = {Annual reports on NMR spectroscopy}, volume = {82}, journal = {Annual reports on NMR spectroscopy}, editor = {Webb, GA}, publisher = {Elsevier}, address = {San Diego}, isbn = {978-0-12-800184-4}, issn = {0066-4103}, doi = {10.1016/B978-0-12-800184-4.00003-5}, pages = {115 -- 166}, year = {2014}, abstract = {The anisotropy effect of functional groups (respectively the ring-current effect of aryl moieties) in H-1 NMR spectra has been computed as spatial NICS (through-space NMR chemical shieldings) and visualized by iso-chemical-shielding surfaces of various size and low(high) field direction. Hereby, the anisotropy/ring-current effect, which proves to be the molecular response property of spatial NICS, can be quantified and can be readily employed for assignment purposes in proton NMR spectroscopy-characteristic examples of stereochemistry and position assignments (the latter in supramolecular structures) will be given. In addition, anisotropy/ring-current effects in H-1 NMR spectra can be quantitatively separated from the second dominant structural effect in proton NMR spectra, the steric compression effect, pointing into the reverse direction, and the ring-current effect, by far the strongest anisotropy effect, can be impressively employed to visualize and quantify (anti) aromaticity and to clear up standing physical-organic phenomena as are pseudo-, spherical, captodative, homo-and chelatoaromaticity, to characterize the pi-electronic structure of, for example, fulvenes, fulvalenes, annulenes or fullerenes and to differentiate aromatic and quinonoid structures.}, language = {en} } @article{MondalBhuniaKellingetal.2014, author = {Mondal, Suvendu Sekhar and Bhunia, Asamanjoy and Kelling, Alexandra and Schilde, Uwe and Janiak, Christoph and Holdt, Hans-J{\"u}rgen}, title = {Giant Zn-14 molecular building block in hydrogen-bonded network with permanent porosity for gas uptake}, series = {Journal of the American Chemical Society}, volume = {136}, journal = {Journal of the American Chemical Society}, number = {1}, publisher = {American Chemical Society}, address = {Washington}, issn = {0002-7863}, doi = {10.1021/ja410595q}, pages = {44 -- 47}, year = {2014}, abstract = {In situ imidazolate-4,5-diamide-2-olate linker generation leads to the formation of a [Zn-14(L2)(12)(O)-(OH)(2)(H2O)(4)] molecular building block (MBB) with a Zn-6 octahedron inscribed in a Zn-8 cube. The MBBs connect by amide-amide hydrogen bonds to a 3D robust supramolecular network which can be activated for N-2, CO2, CH4, and H-2 gas sorption.}, language = {en} } @article{KroenerSchimkaKlamroth2014, author = {Kroener, Dominik and Schimka, Selina and Klamroth, Tillmann}, title = {Laser control for coupled torsions in chiroptical switches: a combined quantum and classical dynamics approach}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {118}, journal = {The journal of physical chemistry : C, Nanomaterials and interfaces}, number = {2}, publisher = {American Chemical Society}, address = {Washington}, issn = {1932-7447}, doi = {10.1021/jp410342a}, pages = {1322 -- 1331}, year = {2014}, abstract = {We present a novel laser pulse control for the chiroptical switch 1-(2-cis-fluoroethenyl)-2-fluoro-3,5-dibromobenzene mounted on adamantane, where the latter imitates a linker group or part of a solid surface. This molecular device offers three switching states: a true achiral "off"-state and two chiral "on"-states of opposite handedness. Due to the alignment of its chiral axis along the surface normal several defined orientations of the switch have to be considered for an efficient stereocontrol strategy. In addition to these different initial conditions, coupled torsional degrees of freedom around the chiral axis make the quest for highly stereoselective laser pulses a challenge. The necessary flexibility in pulse accomplished by employing the iterative stochastic pulse optimization method we presented recently. Still, the complexity of the system dictates a combined treatment by fast molecular dynamics and computationally intensive quantum dynamics. Although quantum effects are found to be of importance, the pulses optimized within the classical treatment allow us to turn on the chirality of the switch, achieving high enantioselectivity in the quantum treatment for all orientations at the same time.}, language = {en} } @article{KovachKoetzFriberg2014, author = {Kovach, Ildyko and Koetz, Joachim and Friberg, Stig E.}, title = {Janus emulsions stabilized by phospholipids}, series = {Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects}, volume = {441}, journal = {Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2013.08.065}, pages = {66 -- 71}, year = {2014}, abstract = {Janus emulsions were formed by mixing three immiscible liquids; this implies two oil components (i.e. olive oil (00) and silicone oil (SiO)) with water in presence of interfacial active components. The morphology and size of Janus droplets formed strongly depended on the type of surfactant used. In presence of a non-ionic surfactant, i.e. Tween 80, large engulfed Janus droplets were formed. By adding phospholipids to the system the droplet size was decreased and more stable Janus droplets formed. Interfacial tension measurements carried out using a spinning drop apparatus and a ring tensiometer demonstrate that interfacial tension is the most important factor controlling the size, morphology and stability of Janus droplets. When the interfacial tension between oil and water becomes <= 1 mN/m, smaller Janus droplets are formed. Such conditions are fulfilled when phospholipids are used in combination with non-ionic surfactant Tween 80. The morphology of the double droplets is predominantly controlled by the viscosity and interfacial tension between the two oil phases. By using different types of phospholipids, i.e. asolectin and lecithin instead of a more concentrated phosphatidylcholine (phospholipon), the interfacial tension is decreased and different morphologies of engulfing can be observed.}, language = {en} } @article{ZakrevskyyCywinskiCywinskaetal.2014, author = {Zakrevskyy, Yuriy and Cywinski, Piotr and Cywinska, Magdalena and Paasche, Jens and Lomadze, Nino and Reich, Oliver and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Santer, Svetlana}, title = {Interaction of photosensitive surfactant with DNA and poly acrylic acid}, series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, volume = {140}, journal = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, number = {4}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0021-9606}, doi = {10.1063/1.4862679}, pages = {8}, year = {2014}, language = {en} } @article{KosmellaVenusHahnetal.2014, author = {Kosmella, Sabine and Venus, Jane and Hahn, Jennifer and Prietzel, Claudia Christina and Koetz, Joachim}, title = {Low-temperature synthesis of polyethyleneimine-entrapped CdS quantum dots}, series = {Chemical physics letters}, volume = {592}, journal = {Chemical physics letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0009-2614}, doi = {10.1016/j.cplett.2013.12.019}, pages = {114 -- 119}, year = {2014}, abstract = {This Letter is focused on the one-pot formation of CdS nanoparticles in aqueous medium in presence of polyethyleneimine (PEI). Quantum dots can be obtained by adding a pre-cooled aqueous Na2S solution to a pre-cooled aqueous CdCl2 solution dropwise in presence of PEI. Field flow fractionation in combination with TEM experiments show a time dependent agglomeration of individual quantum dots from 1.6 nm up to 3.2 nm in size. The hyperbranched PEI of moderate molar mass (>20000 g/mol) is an excellent polymer to prevent a further increase of the particle size. Therefore, stable fluorescent PEI-capped CdS quantum dots are available.}, language = {en} } @article{KopecNiemiecLaschewskyetal.2014, author = {Kopec, Maciej and Niemiec, Wiktor and Laschewsky, Andr{\´e} and Nowakowska, Maria and Zapotoczny, Szczepan}, title = {Photoinduced energy and electron transfer in micellar multilayer films}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {118}, journal = {The journal of physical chemistry : C, Nanomaterials and interfaces}, number = {4}, publisher = {American Chemical Society}, address = {Washington}, issn = {1932-7447}, doi = {10.1021/jp410808z}, pages = {2215 -- 2221}, year = {2014}, abstract = {Micellar multilayer films were prepared from an amphiphilic comb-like polycation ("polysoap") and the polyanion poly(styrene sulfonate) (PSS) using alternate polyelectrolyte layer-by-layer (LbL) self-assembly. Linear growth of the film thickness was evidenced by UV-vis spectroscopy and spectroscopic ellipsometry. Imaging by atomic force microscopy (AFM) indicated that the micellar conformation adopted by the polycation in solutions was preserved in the films. Thus, hydrophobic photoactive molecules, which were solubilized by the hydrophobic nanodomains of the micellar polymer prior to deposition, could be transferred into the films. Photoinduced energy transfer was observed in the nanostructured multilayers between naphthalene (donor) and perylene (acceptor) molecules embedded inside the polymer micelles. The efficiency of the energy transfer process can be controlled to some extent by introducing spacer layers between the layers containing the donor or acceptor, revealing partial stratification of the micellar LbL films. Also, photoinduced electron transfer was evidenced between perylene (donor) and butyl viologen (acceptor) molecules embedded inside the multilayers by steady-state fluorescence spectroscopy. The obtained photoactive nanostructures are promising candidates for solar-to-chemical energy conversion systems.}, language = {en} } @inproceedings{ArltSchwiebsPfarretal.2014, author = {Arlt, Olga and Schwiebs, Anja and Pfarr, Kathrin and Ranglack, Annika and Bouzas, Ferreiros Nerea and Schreiber, Yannick and Neuber, Corinna and Kleuser, Burkhard and Pfeilschifter, Josef M. and Radeke, Heinfried H.}, title = {Dynamic interaction between sphingolipid enzymes, S1P and inflammatory cytokine regulation in dendritic cells}, series = {NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY}, volume = {387}, booktitle = {NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY}, publisher = {Springer}, address = {New York}, issn = {0028-1298}, pages = {S91 -- S91}, year = {2014}, language = {en} } @misc{Boese2014, author = {Boese, Adrian Daniel}, title = {Assessment of coupled cluster theory and more approximate methods for Hydrogen Bonded Systems (vol 9, pg 4403, 2013)}, series = {Journal of chemical theory and computation}, volume = {10}, journal = {Journal of chemical theory and computation}, number = {2}, publisher = {American Chemical Society}, address = {Washington}, issn = {1549-9618}, doi = {10.1021/ct500041j}, pages = {893 -- 893}, year = {2014}, language = {en} } @article{SuttonKoerzdoerferGrayetal.2014, author = {Sutton, Christopher and K{\"o}rzd{\"o}rfer, Thomas and Gray, Matthew T. and Brunsfeld, Max and Parrish, Robert M. and Sherrill, C. David and Sears, John S. and Bredas, Jean-Luc}, title = {Accurate description of torsion potentials in conjugated polymers using density functionals with reduced self-interaction error}, series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, volume = {140}, journal = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr}, number = {5}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0021-9606}, doi = {10.1063/1.4863218}, pages = {9}, year = {2014}, abstract = {We investigate the torsion potentials in two prototypical pi-conjugated polymers, polyacetylene and polydiacetylene, as a function of chain length using different flavors of density functional theory. Our study provides a quantitative analysis of the delocalization error in standard semilocal and hybrid density functionals and demonstrates how it can influence structural and thermodynamic properties. The delocalization error is quantified by evaluating the many-electron self-interaction error (MESIE) for fractional electron numbers, which allows us to establish a direct connection between the MESIE and the error in the torsion barriers. The use of non-empirically tuned long-range corrected hybrid functionals results in a very significant reduction of the MESIE and leads to an improved description of torsion barrier heights. In addition, we demonstrate how our analysis allows the determination of the effective conjugation length in polyacetylene and polydiacetylene chains.}, language = {en} } @article{TsendraScottGorbetal.2014, author = {Tsendra, Oksana and Scott, Andrea Michalkova and Gorb, Leonid and Boese, Adrian Daniel and Hill, Frances C. and Ilchenko, Mykola M. and Leszczynska, Danuta and Leszczynski, Jerzy}, title = {Adsorption of Nitrogen-Containing Compounds on the (100) alpha-Quartz Surface: Ab Initio Cluster Approach}, series = {The journal of physical chemistry : C, Nanomaterials and interfaces}, volume = {118}, journal = {The journal of physical chemistry : C, Nanomaterials and interfaces}, number = {6}, publisher = {American Chemical Society}, address = {Washington}, issn = {1932-7447}, doi = {10.1021/jp406827h}, pages = {3023 -- 3034}, year = {2014}, abstract = {A cluster approach extended to the ONIOM methodology has been applied using several density functionals and Moller-Plesset perturbation theory (MP2) to simulate the adsorption of selected nitrogen-containing compounds [NCCs, 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), 2,4-dinitroanisole (DNAN), and 3-nitro-1,2,4-triazole-5-one (NTO)] on the hydroxyated (100) surface of a-quartz. The structural properties were calculated using the M06-2X functional and 6-31G(d,p) basis set. The M06-2X-D3, PBE-D3, and MP2 methods were used to calculate the adsorption energies. Results have been compared with the data from other studies of adsorption of compounds of similar nature on silica. Effect of deformation of the silica surface and adsorbates on the binding energy values was also studied. The atoms in molecules (AIM) analysis was employed to characterize the adsorbate-adsorbent binding and to calculate the bond energies. The silica surface shows different sorption affinity toward the chemicals considered depending on their electronic structure. All target NCCs are physisorbed on the modeled silica surface. Adsorption occurs due to the formation of multiple hydrogen bonds between the functional groups of NCCs and surface silanol groups. Parallel orientation of NCCs interacting with the silica surface was found to be favorable when compared with perpendicularly oriented NCCs. NTO was found to be the most strongly adsorbed on the silica surface among all of the considered compounds. Dispersion correction was shown to play an important role in the DFT calculations of the adsorption energies of silica-NCC systems.}, language = {en} } @article{CywinskiMoroLoehmannsroeben2014, author = {Cywinski, Piotr J. and Moro, Artur J. and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {Cyclic GMP recognition using ratiometric QD-fluorophore conjugate nanosensors}, series = {Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics}, volume = {52}, journal = {Biosensors and bioelectronics : the principal international journal devoted to research, design development and application of biosensors and bioelectronics}, publisher = {Elsevier}, address = {Oxford}, issn = {0956-5663}, doi = {10.1016/j.bios.2013.09.002}, pages = {288 -- 292}, year = {2014}, language = {en} } @article{StrehmelBerdzinskiStrauchetal.2014, author = {Strehmel, Veronika and Berdzinski, Stefan and Strauch, Peter and Hoffmann-Jacobsen, Kerstin and Strehmel, Bernd}, title = {Investigation of molecular solvents and ionic liquids with a dual probe}, series = {Zeitschrift f{\"u}r physikalische Chemie : international journal of research in physical chemistry and chemical physics}, volume = {228}, journal = {Zeitschrift f{\"u}r physikalische Chemie : international journal of research in physical chemistry and chemical physics}, number = {2-3}, publisher = {De Gruyter}, address = {Berlin}, issn = {0942-9352}, doi = {10.1515/zpch-2014-0453}, pages = {155 -- 169}, year = {2014}, abstract = {A dual probe was investigated by UV-Vis, fluorescence, and ESR spectroscopy. It comprises the pyrene chromophore and the paramagnetic 2,2,6,6-tetramethylpiperidinyl-N-oxyl radical that are covalently linked together via an ester bridge. The dual probe was used to investigate molecular solvents of different polarity as well as ionic liquids bearing either imidazolium or pyrrolidinium cations and various anions, such as bis(trifluoromethylsulfonyl)imide, tetrafluoroborate, tris(pentafluoroethyl)trifluorophosphate, or dicyanamide. The dual probe does not show solvatochromism that is typical for some pyrenes. Furthermore, the dual probe is considerable less mobile compared to 2,2,6,6-tetramethylpiperidinyl-N-oxyl (TEMPO) without additional substituent as detected by ESR spectroscopy. This is caused by the bulky pyrenyl substituent bound at the dual probe resulting in a reduced mobility of the dual probe.}, language = {en} } @article{SchmidtHauke2014, author = {Schmidt, Bernd and Hauke, Sylvia}, title = {Metathesis-Based de novo synthesis of noviose}, series = {European journal of organic chemistry}, volume = {2014}, journal = {European journal of organic chemistry}, number = {9}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1434-193X}, doi = {10.1002/ejoc.201301615}, pages = {1951 -- 1960}, year = {2014}, abstract = {The rare carbohydrate L-(+)-noviose was synthesized from enantiomerically pure L-lactate. The configuration at C-4 was established by diastereoselective nucleophilic addition to an in-situ-generated lactaldehyde. The resulting homoallylic alcohol was further transformed into a set of ring-closing metathesis (RCM) precursors. These compounds were converted into noviose in few steps using RCM and RCM-allylic-oxidation sequences.}, language = {en} } @article{OmosaAmuguneNdundaetal.2014, author = {Omosa, Leonidah K. and Amugune, Beatrice and Ndunda, Beth and Milugo, Trizah K. and Heydenreich, Matthias and Yenesew, Abiy and Midiwo, Jacob O.}, title = {Antimicrobial flavonoids and diterpenoids from Dodonaea angustifolia}, series = {South African journal of botany : an international interdisciplinary journal for botanical sciences}, volume = {91}, journal = {South African journal of botany : an international interdisciplinary journal for botanical sciences}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0254-6299}, doi = {10.1016/j.sajb.2013.11.012}, pages = {58 -- 62}, year = {2014}, language = {en} } @article{HartmannLewerenz2014, author = {Hartmann, Heike and Lewerenz, Susann}, title = {Campaigning against Apartheid in East and West Germany}, series = {Radical history review}, journal = {Radical history review}, number = {119}, publisher = {Duke Univ. Press}, address = {Durham}, issn = {0163-6545}, doi = {10.1215/01636545-2402068}, pages = {191 -- 204}, year = {2014}, language = {en} } @article{OmorogieBabalolaUnuabonahetal.2014, author = {Omorogie, Martins O. and Babalola, Jonathan Oyebamiji and Unuabonah, Emmanuel Iyayi and Gong, Jian R.}, title = {Hybrid materials from agro-waste and nanoparticles: implications on the kinetics of the adsorption of inorganic pollutants}, series = {Environmental technology}, volume = {35}, journal = {Environmental technology}, number = {5}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {0959-3330}, doi = {10.1080/09593330.2013.839747}, pages = {611 -- 619}, year = {2014}, abstract = {This study is a first-hand report of the immobilization of Nauclea diderrichii seed waste biomass (ND) (an agro-waste) with eco-friendly mesoporous silica (MS) and graphene oxide-MS (GO+MS ) nanoparticles, producing two new hybrid materials namely: MND adsorbent for agro-waste modified with MS and GND adsorbent for agro-waste modified with GO+MS nanoparticles showed improved surface area, pore size and pore volume over those of the agro-waste. The abstractive potential of the new hybrid materials was explored for uptake of Cr(III) and Pb(II) ions. Analysis of experimental data from these new hybrid materials showed increased initial sorption rate of Cr(III) and Pb(II) ions uptake. The amounts of Cr(III) and Pb(II) ions adsorbed by MND and GND adsorbents were greater than those of ND. Modification of N. diderrichii seed waste significantly improved its rate of adsorption and diffusion coefficient for Cr(III) and Pb(II) more than its adsorption capacity. The rate of adsorption of the heavy metal ions was higher with GO+MS nanoparticles than for other adsorbents. Kinetic data were found to fit well the pseudo-second-order and the diffusion-chemisorption kinetic models suggesting that the adsorption of Cr(III) and Pb(II) onto these adsorbents is mainly through chemisorption mechanism. Analysis of kinetic data with the homogeneous particle diffusion kinetic model suggests that particle diffusion (diffusion of ions through the adsorbent) is the rate-limiting step for the adsorption process.}, language = {en} } @article{StrehmelBerdzinskiRexhausen2014, author = {Strehmel, Veronika and Berdzinski, Stefan and Rexhausen, Hans}, title = {Interactions between ionic liquids and radicals}, series = {Journal of molecular liquids}, volume = {192}, journal = {Journal of molecular liquids}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0167-7322}, doi = {10.1016/j.molliq.2013.12.007}, pages = {153 -- 170}, year = {2014}, abstract = {Ionic liquids were investigated with both stable radicals on the basis of 2,2,6,6-tetramethylpiperidine-1-yloxyl (TEMPO) and photogenerated lophyl radicals. The ionic liquids are composed either of bis(trifluoromethylsulfonyl)imide (NTf2) as anion and various cations or they contain an imidazolium ion in combination with various anions. The cations include imidazolium, pyrrolidinium, piperidinium, polymethine or ammonium ions. Furthermore, BF4-, PF6-, triflate, camphorsulfonate, lactate, tosylate or tris(pentafluoroethyl) trifluorophosphate (FAP) are the counter ions in the imidazolium salts. The structural variation of the ionic liquids results in differences in glass formation, semiaystallinity, or crystallinity, as well as in viscosity differences. Furthermore, a vinyl substituent at the imidazolium ion and a methacryloyloxyethyl substituent at the ammonium ion result in polymerizable ionic liquids that were converted via a radical mechanism in amorphous polymerized ionic liquids with a glass transition temperature, which is significantly higher compared to the ionic liquids. An additional substituent at TEMPO causes additional hydrogen bond formation or additional Coulomb interactions with the individual ions of the ionic liquids compared to TEMPO. This influences the mobility of these radicals in the ionic liquid expressed by differences in the average rotational correlation time (T-rot). The mobility of the radicals in the ionic liquids as function of the temperature describes ionic liquids either as continuum in analogy to molecular solvents using the Stokes-Einstein model, that is the case for 1-butyl-3-methylimidazolium NTf2, or as medium where free volume effects are important for the mobility of a solute in the ionic liquid using the model of Spernol, Gierer, and Wirtz. The 1-butyl-3-methylimidazolium BF4- fits well into the latter. Furthermore, the isotropic hyperfine coupling constant (A(iso)(N-14)) of the stable radicals gives information about micropolarity of the ionic liquids only if the mobility of the radical is high enough in the ionic liquid. In addition to the rotational mobility of the stable radicals, the photogenerated lophyl radicals give information about translational diffusion of radicals and solvent cage effects in the ionic liquids. The application of the Eyring equation results mostly in the expected negative values of the activation entropy for the transition state that is typical for bimolecular reactions. Only few examples show a less negative or positive activation entropy for the bimolecular reaction, which may be attributed to radical recombination within the solvent cage to a high extent. The results obtained during investigation of radicals in ionic liquids are important to understand the radical processes in ionic liquids that may occur for example in dye sensitized solar cells, photo or thermally induced reactions or radical polymerizations in ionic liquids.}, language = {en} } @unpublished{Riemer2014, author = {Riemer, Martin}, title = {Allyl alkyl carbonates}, series = {Synlett : accounts and rapid communications in synthetic organic chemistry}, volume = {25}, journal = {Synlett : accounts and rapid communications in synthetic organic chemistry}, number = {7}, publisher = {Thieme}, address = {Stuttgart}, issn = {0936-5214}, doi = {10.1055/s-0033-1340862}, pages = {1041 -- 1042}, year = {2014}, language = {en} } @article{WeissWienkBoelensetal.2014, author = {Weiss, Jan and Wienk, Hans and Boelens, Rolf and Laschewsky, Andr{\´e}}, title = {Block copolymer micelles with an intermediate star-/flower-like structure studied by H-1 NMR relaxometry}, series = {Macromolecular chemistry and physics}, volume = {215}, journal = {Macromolecular chemistry and physics}, number = {9}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1352}, doi = {10.1002/macp.201300753}, pages = {915 -- 919}, year = {2014}, abstract = {H-1 NMR relaxation is used to study the self-assembly of a double thermoresponsive diblock copolymer in dilute aqueous solution. Above the first transition temperature, at which aggregation into micellar structures is observed, the trimethylsilyl (TMS)-labeled end group attached to the shell-forming block shows a biphasic T-2 relaxation. The slow contribution reflects the TMS groups located at the periphery of the hydrophilic shell, in agreement with a star-like micelle. The fast T-2 contribution corresponds to the TMS groups, which fold back toward the hydrophobic core, reflecting a flower-like micelle. These results confirm the formation of block copolymer micelles of an intermediate nature (i.e., of partial flower-like and star-like character), in which a part of the TMS end groups folds back to the core due to hydrophobic interactions.}, language = {en} } @article{DereseBarasaAkalaetal.2014, author = {Derese, Solomon and Barasa, Leonard and Akala, Hoseah M. and Yusuf, Amir O. and Kamau, Edwin and Heydenreich, Matthias and Yenesew, Abiy}, title = {4 '-Prenyloxyderrone from the stem bark of Millettia oblata ssp teitensis and the antiplasmodial activities of isoflavones from some Millettia species}, series = {Phytochemistry letters}, volume = {8}, journal = {Phytochemistry letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1874-3900}, doi = {10.1016/j.phytol.2014.02.001}, pages = {69 -- 72}, year = {2014}, abstract = {The CH2Cl2/MeOH (1: 1) extract of the stem bark of Millettia oblata ssp. teitensis showed antiplasmodial activity (IC50 = 10-12 mu g/mL) against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Chromatographic separation of the extract led to the isolation of a new isoflavone, 4'-prenyloxyderrone (1), together with known isoflavones (8-O-methylretusin, durmillone, maximaisoflavone B, maximaisoflavone H and maximaisoflavone J), a rotenoid (tephrosin) and a triterpene (lupeol). Similar investigation of Millettia leucantha resulted in the identification of the isoflavones afrormosin and wistin, and the flavone chrysin. The identification of these compounds was based on their spectroscopic data. Five of the isoflavones isolated from these plants as well as 11 previously reported compounds from Millettia dura were tested and showed good to moderate antiplasmodial activities (IC50 = 13-53 mu M), with the new compound, 4'-prenyloxyderrone, being the most active (IC50 = 13-15 mu M).}, language = {en} } @article{EisoldKupstatKlieretal.2014, author = {Eisold, Ursula and Kupstat, Annette and Klier, Dennis Tobias and Primus, Philipp-A. and Pschenitza, Michael and Niessner, Reinhard and Knopp, Dietmar and Kumke, Michael Uwe}, title = {Probing the physicochemical interactions of 3-hydroxy-benzo[a]pyrene with different monoclonal and recombinant antibodies by use of fluorescence line-narrowing spectroscopy}, series = {Analytical \& bioanalytical chemistry}, volume = {406}, journal = {Analytical \& bioanalytical chemistry}, number = {14}, publisher = {Springer}, address = {Heidelberg}, issn = {1618-2642}, doi = {10.1007/s00216-013-7584-8}, pages = {3387 -- 3394}, year = {2014}, abstract = {Characterization of interactions between antigens and antibodies is of utmost importance both for fundamental understanding of the binding and for development of advanced clinical diagnostics. Here, fluorescence line-narrowing (FLN) spectroscopy was used to study physicochemical interactions between 3-hydroxybenzo[a]pyrene (3OH-BaP, as antigen) and a variety of solvent matrices (as model systems) or anti-polycyclic aromatic hydrocarbon antibodies (anti-PAH). We focused the studies on the specific physicochemical interactions between 3OH-BaP and different, previously obtained, monoclonal and recombinant anti-PAH antibodies. Control experiments performed with non-binding monoclonal antibodies and bovine serum albumin (BSA) indicated that nonspecific interactions did not affect the FLN spectrum of 3OH-BaP. The spectral positions and relative intensities of the bands in the FLN spectra are highly dependent on the molecular environment of the 3OH-BaP. The FLN bands correlate with different vibrational modes of 3OH-BaP which are affected by interactions with the molecular environment (pi-pi interactions, H-bonding, or van-der-Waals forces). Although the analyte (3OH-BaP) was the same for all the antibodies investigated, different binding interactions could be identified from the FLN spectra on the basis of structural flexibility and conformational multiplicity of the antibodies' paratopes.}, language = {en} } @article{XieHuangTaubert2014, author = {Xie, Zai-Lai and Huang, Xing and Taubert, Andreas}, title = {DyeIonogels: proton-responsive ionogels based on a dye-ionic liquid exhibiting reversible color change}, series = {Advanced functional materials}, volume = {24}, journal = {Advanced functional materials}, number = {19}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1616-301X}, doi = {10.1002/adfm.201303016}, pages = {2837 -- 2843}, year = {2014}, abstract = {Transparent, ion-conducting, and flexible ionogels based on the room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl) imide [Bmim][N(Tf)(2)], the dye-IL (DIL) 1-butyl-3-methylimidazolium methyl orange [Bmim][MO], and poly(methylmethacrylate) (PMMA) are prepared. Upon IL incorporation the thermal stability of the PMMA matrix significantly increases from 220 to 280 degrees C. The ionogels have a relatively high ionic conductivity of 10(-4) S cm(-1) at 373 K. Most importantly, the ionogels exhibit a strong and reversible color change when exposed to aqueous or organic solutions containing protons or hydroxide ions. The resulting material is thus a prototype of soft multifunctional matter featuring ionic conductivity, easy processability, response to changes in the environment, and a strong readout signal, the color change, that could be used in optical data storage or environmental sensing.}, language = {en} } @misc{Laschewsky2014, author = {Laschewsky, Andr{\´e}}, title = {Structures and synthesis of zwitterionic polymers}, series = {Polymers}, volume = {6}, journal = {Polymers}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym6051544}, pages = {1544 -- 1601}, year = {2014}, abstract = {The structures and synthesis of polyzwitterions ("polybetaines") are reviewed, emphasizing the literature of the past decade. Particular attention is given to the general challenges faced, and to successful strategies to obtain polymers with a true balance of permanent cationic and anionic groups, thus resulting in an overall zero charge. Also, the progress due to applying new methodologies from general polymer synthesis, such as controlled polymerization methods or the use of "click" chemical reactions is presented. Furthermore, the emerging topic of responsive ("smart") polyzwitterions is addressed. The considerations and critical discussions are illustrated by typical examples.}, language = {en} } @article{SchmidtRiemer2014, author = {Schmidt, Bernd and Riemer, Martin}, title = {Suzuki-Miyaura coupling of halophenols and phenol boronic acids: systematic investigation of positional isomer effects and conclusions for the synthesis of phytoalexins from Pyrinae}, series = {The journal of organic chemistry}, volume = {79}, journal = {The journal of organic chemistry}, number = {9}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/jo500675a}, pages = {4104 -- 4118}, year = {2014}, abstract = {The Suzuki-Miyaura couplings of o-, m-, and p-halophenols with o-, m-, and p-phenol boronic acids were investigated for all combinations under standardized conditions, using Pd/C as a heterogeneous catalyst and water as a solvent. In the case of iodophenols, conventional heating was used, while for bromophenols significantly better results could be obtained using microwave irradiation. This systematic study revealed that 2,4'-biphenol is particularly difficult to access, irrespective of the starting materials used, but that these difficulties can be overcome by using different additives. The conclusions drawn from this investigation allowed us to identify conditions for the protecting group-free or minimized total synthesis of biaryl-type phytoalexins. These compounds possess antibacterial activity and are produced by fruit trees as a response to microbial infection.}, language = {en} } @article{StumpeSakhnoGritsaietal.2014, author = {Stumpe, Joachim and Sakhno, O. and Gritsai, Y. and Rosenhauer, R. and Fischer, Th. and Rutloh, Michael and Schaal, F. and Weidenfeld, S. and Jetter, M. and Michler, P. and Pruss, C. and Osten, W.}, title = {Active and passive LC based polarization elements}, series = {Molecular crystals and liquid crystals}, volume = {594}, journal = {Molecular crystals and liquid crystals}, number = {1}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {1542-1406}, doi = {10.1080/15421406.2014.917503}, pages = {140 -- 149}, year = {2014}, abstract = {Passive and active polarization elements were created by surface and bulk photo-alignment of LCs, reactive LCs, photo-sensitive LCP and photo-curable monomer/LC composites. The use of different photo-sensitive liquid crystalline materials for the development of highly anisotropic elements with high spatial resolution and stability or, alternatively, fast switch ability will be discussed. Photo-active and voltage tunable polarization and diffraction elements are presented. For active micro-optic application a photo-addressed patterned retarder was created. Electrically switchable diffraction gratings were generated by interference exposure of photo-curable LC composites at room temperature characterized by droplet free morphology. These polarization sensitive diffraction elements are characterized be excellent optical properties and low switching times.}, language = {en} }